# First Measurement!



## THX-UltraII

So proud that I finally did my first measurement tonight. 
How does it look guys?

SETTINGS:
- Marantz SR5005 processor with settings: mode LFE (so not the LFE+MAIN setting), LPF LFE 120Hz, crossover 80Hz, all speakers set on SMALL
- Teufel Theater 8 5.1 surround set http://www.areadvd.de/hardware/teufeltheater8.shtml
- acoustic room profesionally treated with a lot of big basstraps, 6 types of different big diffusers and a Sombra-D ceiling.

I have bought a Behringer FBQ1000 (same as DSP1124) which is now in bypass mode. Looks like there s some work to do for me in the low frequencies. Should I first start to play with settings like LFE mode and crossover freq in my AVR or skip this and go right to my Behringer? 

For your info: my subwoofer phase is already set properly. Move my subwoofer or main speakers is not possible anymore (only a few cm)


----------



## eiger

It's probably going to be helpful if you use the "capture" function within REW, save the graphs as JPEGs or whatever, and then upload the photos to a site and use insert the URL into the post.

(rather than attatch a bunch of files)


----------



## THX-UltraII

Here s some more interesting information (I think).
You see 11 measurements here:

1. crossover 40
2. crossover 60
3. crossover 80
4. crossover 90
5. crossover 100
6. crossover 110
7. crossover 120
8. crossover 150
9. crossover 200
10. crossover 250
11. crossover 250, main speakers disconnected

I think (and correct me if I m wrong) that I can draw the conclusion from this that my low frequencies comming from my subwoofer has problems at:
a. 20-30Hz range
b. 37-44Hz range
c. 54Hz dip
d. 58-69Hz range
e. 75Hz dip


----------



## THX-UltraII

eiger said:


> It's probably going to be helpful if you use the "capture" function within REW, save the graphs as JPEGs or whatever, and then upload the photos to a site and use insert the URL into the post.
> 
> (rather than attatch a bunch of files)


? These are not 'a bunch of files' m8. You can dl my measurement data set and get all the info you need


----------



## eiger

The MDATs you attatched require that that REW be on the PC 

Just post/upload JPEGs of your graphs as others on the forum do and it will be that much easier for others to see what's going on in your room, and/or make reccomendations without having to install REW first.


----------



## fusseli

There is nothing wrong with attaching the measurement files, it's actually more useful for someone else to analyze. It's up to whoever is posting.

What are you measruing with? It looks like you are using a mic without calibrating SPL. Have you made a soundcard calibration and do you have a .cal for your microphone?

Have you tried taking sweeps at multiple listening points?

I see you have your speakers set to small for trying those different crossover points, which is correct, but I'm not seeing as much of a difference in the crossover region for all of those different settings. That being said, your sub's phase setting could need to be adjusted for each different Xover point that you try. The sub by itself isn't too shabby, I would probably pick the 60Hz Xover setting and start playing with some EQ.


----------



## EarlK

THX said:


> You see 11 measurements here:


_I see only a single measurement within that file ._

:sn:

*EDIT :* Oops, my mistake , I'm only looking at the first posted file .


----------



## EarlK

It seems to me that your cross-over frequencies ( within the AVR ) aren't really working as expected . 

ie; Usually as one lowers the crossover frequency, one expects to see some leveling of the mid-bass frequencies such as that 90 to 140hz hump ( this is assuming both your subs & speakers are effected equally by the crossover ) .

:sn:


----------



## THX-UltraII

thxz for your reply EarlK.

I don t understand (yet) what you exactly mean. The red line is with the 250 crossover so in this case the red line untill approx 200Hz is ONLY the subwoofer right? With the 40Hz crossover everything from lets say approx 60Hz or so are my main speakers also correct? I see big differences in the red and aqua lines but you say that something is not right. I don t understand what you mean exactly.

The next information might be important too:
My subwoofer has a setting called 'THX SWITCH'. I can set this on 'FULL RANGE' and 'VARIABLE FREQUENCY CONTROL'. My manual says the following about this:
FULL RANGE: thx setting for all surround modes
VARIABLE FREQUENCY CONTROL: only when running the subwoofer in conjunction with a conventional stereo amplifier.

Next there is the 'FREQUENCY' knob on my subwoofer. My manual says about this:
Controls the crossover frequency between the subwoofer and the front speakers. This control is not active when setting the 'THX SWITCH' on THX MODE. When running the thx front/center speakers and subwoofer in stereo mode, set this control to 80Hz.

I have my settings as follows: THX SWITCH on VARIABLE FREQUENCY CONTROL and FREQUENCY KNOB all the way to the right which is 240Hz.

Could I be doing something wrong here?

You can find the manual of my speaker system here:
http://www.google.nl/url?sa=t&rct=j...PONfrqbWvOh8x5tsQ&sig2=pH1tMvlj-d8bj7451pmi0g. 
On page 7 there is information about the subwoofer.

EDIT:
My phase control knob of my subwoofer ONLY works when setting the THX SWITCH on FULL RANGE so that s why I have it set on FULL RANGE. The manual of the subwoofer says the following about the PHASE KNOB:
This control is not active in THX MODE (thx switch) as the phase is controlled by the AVR.


----------



## THX-UltraII

fusseli said:


> There is nothing wrong with attaching the measurement files, it's actually more useful for someone else to analyze. It's up to whoever is posting.
> 
> What are you measruing with? It looks like you are using a mic without calibrating SPL. Have you made a soundcard calibration and do you have a .cal for your microphone?
> 
> Have you tried taking sweeps at multiple listening points?
> 
> I see you have your speakers set to small for trying those different crossover points, which is correct, but I'm not seeing as much of a difference in the crossover region for all of those different settings. That being said, your sub's phase setting could need to be adjusted for each different Xover point that you try. The sub by itself isn't too shabby, I would probably pick the 60Hz Xover setting and start playing with some EQ.


I m using a cross spectrum calibrated ECM8000 and loaded the narrow_band_response_0_degree.frd file. The ECM8000 is placed at listening/ear position in an exactly horizontal position. My Tascam 122 MKII soundcard is calibrated. 

I have not tried multiple listening positions; first things first and see what s going on at this position. There seems something 'wrong' with the crossover freq control of mt AVR/subwoofer and I want to figure out first what is going on here before trying other positions.


----------



## aackthpt

What you are doing should work but is clearly not what was meant by the manufacturer. They meant for you to use the switch on "full range" as crossovers etc. are in your AVR. The "phase" would be controlled by the distance you set for the sub compared to the other speakers in the AVR--as well as the FBQ assuming it has delay functionality.

If it were me I would do that (switch on full range) and stick with 80Hz crossover. After setting level I'd play with subwoofer distance until the crossover region looked OK, then put that FBQ in there and start tweaking.


----------



## THX-UltraII

> What you are doing should work but is clearly not what was meant by the manufacturer.


But the question is WHY it does not work. I hope EarlK has some idea.



> They meant for you to use the switch on "full range" as crossovers etc. are in your AVR.


That seems odd. Phase (=delay) is a setting that s generally set in a subwoofer (correct me if I m wrong).



> The "phase" would be controlled by the distance you set for the sub compared to the other speakers in the AVR--as well as the FBQ assuming it has delay functionality.


Normally a distance is set by the AVR (via Audessey) and after that you 'fine-tune' the phase(delay) with the phase setting of a subwoofer. At least, this is what I thought.


----------



## aackthpt

THX-UltraII said:


> But the question is WHY it does not work. I hope EarlK has some idea.
> 
> That seems odd. Phase (=delay) is a setting that s generally set in a subwoofer (correct me if I m wrong).
> 
> Normally a distance is set by the AVR (via Audessey) and after that you 'fine-tune' the phase(delay) with the phase setting of a subwoofer. At least, this is what I thought.


I do care why things don't work, but usually find it expedient to move on to figuring out what does work, and when I do figure out what works I magically stop worrying so much about what didn't work.

Phase/delay is normally set in the subwoofer for a two-channel system. However since the relative arrival times of the sounds are important to creating the surround effects, multichannel AVRs have the capability to delay each channel individually (which is precisely what the distance settings for the speakers do). It's been this way for quite a while now (decades). Your subwoofer's switch is basically intended to be a switch between using it with a two-channel rig and using it in a multichannel system. While it's possible to make it work in a nonstandard fashion, I'd start with the simplest setup which happily coincides with the way the manufacturer intended it to be used in your type of system. I don't really find it odd. It's different from systems I have owned, but then I have never owned any THX certified gear either--and I don't really care where things happen as long as that which needs to happen, happens!

Maybe Audyssey is better (I don't know-- I just got my first AVR with Audyssey and have not yet switched it in) but in my experience automagic setups are not very good--they just don't always make sense in terms of the small/large settings and distance settings. I just use an SPL meter and a tape measure (though perhaps I should listen to each and assess how it sounds... that might be an interesting experiment). Anyway it's very common to manually adjust the relative distances between the speakers (which I mean to include the sub here) to achieve a desired effect -- for example to compensate for the acoustic delay of a horn subwoofer.


----------



## Wayne A. Pflughaupt

THX-UltraII said:


> There seems something 'wrong' with the crossover freq control of mt AVR/subwoofer


We've seen instances in the past where some receivers' crossovers only worked when Dolby Digital was active - i.e., not with analog signals. Maybe that's the problem with yours?

Regards
Wayne


----------



## EarlK

THX said:


> But the question is WHY it does not work. I hope EarlK has some idea.












I assume that the presence of that large peak ( between 90 to 140 hz ) can be attributed to getting too much overlap between your sub-woofer & your main speakers .

Reduce the overlap sufficiently , and I assume that the offending peak will disappear .

You can reduce the overlap by implementing Johns suggestion ( by running subs via the standard arrangement ) or ( with the present setup ) by lowering the low-pass frequency on the sub-woofer to something much lower ( & then keeping the mains set to "small" , but maybe hipassed at 100hz ) . You'll need to experiment to see what works best . You might also want to stuff any ports ( if they exist ) on your main speakers .

The point is; there are a few ways to minimize over-lap between mains & subs / / use REW to discover what all the possibilities are ( by measuring each scenario ) . Don't be afraid to turn some knobs, make a measurement with REW to "discover" the results and then log your findings ( either on paper using hand written notes or committed to Word on your computer ) . Once everything is logged for reference, it becomes much easier to choose the best scenario .

:sn:


----------



## THX-UltraII

aackthpt said:


> I do care why things don't work, but usually find it expedient to move on to figuring out what does work, and when I do figure out what works I magically stop worrying so much about what didn't work.
> 
> Phase/delay is normally set in the subwoofer for a two-channel system. However since the relative arrival times of the sounds are important to creating the surround effects, multichannel AVRs have the capability to delay each channel individually (which is precisely what the distance settings for the speakers do). It's been this way for quite a while now (decades). Your subwoofer's switch is basically intended to be a switch between using it with a two-channel rig and using it in a multichannel system. While it's possible to make it work in a nonstandard fashion, I'd start with the simplest setup which happily coincides with the way the manufacturer intended it to be used in your type of system. I don't really find it odd. It's different from systems I have owned, but then I have never owned any THX certified gear either--and I don't really care where things happen as long as that which needs to happen, happens!
> 
> Maybe Audyssey is better (I don't know-- I just got my first AVR with Audyssey and have not yet switched it in) but in my experience automagic setups are not very good--they just don't always make sense in terms of the small/large settings and distance settings. I just use an SPL meter and a tape measure (though perhaps I should listen to each and assess how it sounds... that might be an interesting experiment). Anyway it's very common to manually adjust the relative distances between the speakers (which I mean to include the sub here) to achieve a desired effect -- for example to compensate for the acoustic delay of a horn subwoofer.


thxz for your reply. So what you say is that it s best to put the THX switch on FULL RANGE?
If so, my subwoofer will disable:
1. the Phase knob. This is no problem as I can find the right phase with the distance setting of the subwoofer in my AVR.
2. the FREQUENCY KNOB. The manual of the Teufel subwoofer says 'this control is not active in THX mode', which is THX switch on FULL RANGE (i think). This leaves me with the question that *what IS active in this setting.....*


----------



## THX-UltraII

Wayne A. Pflughaupt said:


> We've seen instances in the past where some receivers' crossovers only worked when Dolby Digital was active - i.e., not with analog signals. Maybe that's the problem with yours?
> 
> Regards
> Wayne


Is there a way to check this?


----------



## THX-UltraII

> You can reduce the overlap by implementing Johns suggestion ( by running subs via the standard arrangement )


? What do you mean with this (Johns) suggestion exactly? I don t understand.



> or ( with the present setup ) by lowering the low-pass frequency on the sub-woofer to something much lower ( & then keeping the mains set to "small" , but maybe hipassed at 100hz )


But the low pass freq. on the subwoofer is not active when I will put my subwoofer in FULL RANGE mode (see my reply to aackthpt two posts back)



> You might also want to stuff any ports ( if they exist ) on your main speakers .


no ports on my mains 



> The point is; there are a few ways to minimize over-lap between mains & subs / / use REW to discover what all the possibilities are ( by measuring each scenario ) . Don't be afraid to turn some knobs, make a measurement with REW to "discover" the results and then log your findings ( either on paper using hand written notes or committed to Word on your computer ) . Once everything is logged for reference, it becomes much easier to choose the best scenario


ok thxz


----------



## EarlK

THX said:


> ? What do you mean with this (Johns) suggestion exactly? I don t understand.


- I assume that John meant that you should go back to using a typical Bass Management implementation ( as is typically found within an AVR for running Subwoofers with Mains speakers ) . 
- This is the scenario where the AVR applies (if you decide to choose 80hz as acrossoer point ) an 80hz HighPass filter to the Mains and an 80hz LowPass filter to the subs .
- I would call this approach, a "symmetrical" arrangement to bass management . It minimizes overlap at the expense of some flexibility .

- Currently ( from what I understand ), your arrangement is asymmetrical ( in that it allows you to choose 2 different frequency points for either of the HiPass or LowPass filters . ) 

- It is this arrangement ( & it's misuse ) that has caused ( I'm speculating ) the big hump between 90 & 140hz . 

:sn:


----------



## Wayne A. Pflughaupt

THX-UltraII said:


> Is there a way to check this?


One way would be to feed REW straight into your subwoofer input, and then take measurements with the same crossover settings you were using with the AVR.

Another way, unplug the main speakers and play a sine-wave tone through the receiver (to the sub) that’s one octave above the crossover frequency (e.g. 160 Hz for a 80 Hz crossover). Assuming the AVR’s crossover is 24 dB/octave, the one-octave-higher signal should be down about that much, or close to it.

Regards, 
Wayne


----------



## THX-UltraII

EarlK said:


> - I assume that John meant that you should go back to using a typical Bass Management implementation ( as is typically found within an AVR for running Subwoofers with Mains speakers ) .
> - This is the scenario where the AVR applies (if you decide to choose 80hz as acrossoer point ) an 80hz HighPass filter to the Mains and an 80hz LowPass filter to the subs .
> - I would call this approach, a "symmetrical" arrangement to bass management . It minimizes overlap at the expense of some flexibility .
> 
> - Currently ( from what I understand ), your arrangement is asymmetrical ( in that it allows you to choose 2 different frequency points for either of the HiPass or LowPass filters . )
> 
> - It is this arrangement ( & it's misuse ) that has caused ( I'm speculating ) the big hump between 90 & 140hz .
> 
> :sn:


I cannot set frequency points of the HiPass and LowPass filters. At least, I don t think I can. In my avr I can only set a crossover frequency (40, 60, 80, 90, 100, 110, 120, 150, 200 and 250). A crossover freq. is nothing more then my avr sending everything below eg. 60Hz to the subwoofer and everything above 60Hz to the main (with a rolloff). I have also a setting called LPF of LFE. I have set this on 120Hz. I think this applies to only the LFE signal (in a 5.1 track) and that this means that the subwoofer plays all the frequencies up to 120Hz from the .1 signal.


----------



## THX-UltraII

Wayne A. Pflughaupt said:


> One way would be to feed REW straight into your subwoofer input, and then take measurements with the same crossover settings you were using with the AVR.
> Regards,
> Wayne


Will try this today and report back.

Guys, still don t know if there is something 'wrong' with measurements I took and how I have to config my subwoofer settings (on the subwoofer itself) :huh:


----------



## THX-UltraII

I did some more testing this morning (not yet your suggestion Wayne but the suggestion from EarlK to turn on and off some knobs and change some settings and make measurements). All the 8 tests I did are with different settings in my AVR and on my subwoofer (not played with the crossover of my AVR this time). All test where done with AVR in mode STEREO and subwoofer distance in AVR on the same 4.30m. In my next reply I have made a Excel for the ones that have Excel so that the differences in measurements are easier to read. As attachtment on the bottom of this reply there is also the .mdat file so you guys can take a closer look at the graphs and compare them easier. I hope the differences I made in all settings are clear for your guys.


*graph 1*
AVR:
- speakers SMALL
- bass setting: mode LFE
- crossover: 80

SUBWOOFER:
- switch on VARIABLE FREQ. CONTROL
- VARIABLE FREQ. CONTROL knob active and on 240
- PHASE knob active and on 80%

*graph 2*
AVR:
- speakers LARGE
- bass setting: mode LFE
- crossover: NOT SELECTABLE with above settings

SUBWOOFER:
- switch on VARIABLE FREQ. CONTROL
- VARIABLE FREQ. CONTROL knob active and on 240
- PHASE knob active and on 80%

*graph 3*
AVR:
- speakers LARGE
- bass setting: mode LFE+MAIN
- crossover: 80

SUBWOOFER:
- switch on VARIABLE FREQ. CONTROL
- VARIABLE FREQ. CONTROL knob active and on 240
- PHASE knob active and on 80%

*graph 4*
AVR:
- speakers SMALL
- bass setting: mode LFE
- Crossover: 80

SUBWOOFER:
- switch on FULL RANGE
- VARIABLE FREQ. CONTROL knob not active
- PHASE knob not active

*graph 5*
AVR:
- speakers LARGE
- bass setting: mode LFE
- crossover: NOT SELECTABLE with above settings

SUBWOOFER:
- switch on FULL RANGE
- VARIABLE FREQ. CONTROL knob not active
- PHASE knob not active

*graph 6*
AVR:
- speakers LARGE
- bass setting: mode LFE+MAIN
- crossover: 80

SUBWOOFER:
- switch on FULL RANGE
- VARIABLE FREQ. CONTROL knob not active
- PHASE knob not active

*graph 7*
AVR:
- speakers SMALL
- bass setting: mode LFE+MAIN
- crossover: 80

SUBWOOFER:
- switch on VARIABLE FREQ. CONTROL
- VARIABLE FREQ. CONTROL knob active and on 240
- PHASE knob active and on 80%

*graph 8*
AVR:
- speakers SMALL
- bass setting: mode LFE+MAIN
- crossover: 80

SUBWOOFER:
- switch on FULL RANGE
- VARIABLE FREQ. CONTROL knob not active
- PHASE knob not active


----------



## THX-UltraII

I also made a Excel file to make the 8 different graphs easier to read


----------



## JohnM

If you want to see what your AVR is doing to the signal connect the AVR's line output directly to the soundcard input.


----------



## aackthpt

JohnM said:


> If you want to see what your AVR is doing to the signal connect the AVR's line output directly to the soundcard input.


That's a good point, if it has pre-outs, then run a sweep from a main preout and the sub-out with a given setting... rinse and repeat for various settings. I've done it on my Marantz receiver's sub-out to see how low its LF passband went--worked great!


----------



## EarlK

THX said:


> <snip> All the 8 tests I did are with different settings in my AVR and on my subwoofer (not played with the crossover of my AVR this time). <snip>


I note that all eight of those approaches were pretty a failure at reducing the offending peak ( the one between 90 to 140hz caused I think by having too much signal overlap between your sub & mains ) .

Since you are spread-sheet savy / I suggest that you make up a SS of all the permutations & combinations that you have tried to date / and then log the results for reference .

Note : you have yet to try Johns ( aackthpt ) suggestion of running the system normally / ie; using the built in crossovers from the AVR .

Is there some reason you don't what to go down that road ?

:sn:


----------



## THX-UltraII

aackthpt said:


> That's a good point, if it has pre-outs, then run a sweep from a main preout and the sub-out with a given setting... rinse and repeat for various settings


My SR5005 has pre-outs indeed. Do you mean to run a sweep from the main (L or R) pre-out to the L or R 1/4'' jack input of the Tascam simultanously with the sub pre-out on the L or R 1/4'' jack input of the Tascam?

I could also run a sweep my only my mains and one with only my subwoofer. This could also be valuable information maybe?


----------



## THX-UltraII

> I note that all eight of those approaches were pretty a failure at reducing the offending peak ( the one between 90 to 140hz caused I think by having too much signal overlap between your sub & mains )


I did those tests to see what differences I would get in the results and not really to see if the bump would go away. After all these measurements I already learned a few things. One of the things I learned is that the setting in a AVR with the SMALL+LFE/MAIN combination gives the exact same result as setting your AVR to SMALL+only LFE. This is because the 'LFE mode' (it s called different on various AVRs) only has effect when you set your speakers to LARGE. That is also why GRAPH 1+GRAPH 7 and GRAPH 4+8 look the same (because the settings are not different from each other although you would assume they are different). I have also learned that setting my speakers on LARGE is not even a option. One can ONLY set speakers on LARGE if the speakers are truly full range and by this I mean capable of 20-20000Hz (so eg. the b&w 800D ). 

When all this information I can already forget the settings I used in GRAPH 2,3,5,6,7 and 8. This leaves settings 1 and 4 (remember I am NOT YET talking about the crossover setting in my AVR!). As you can see in my excel the differences between the settings used in Graph 1 and 4 are the settings on my subwoofer. Graph 1 looks better than Graph 4 as you can see but (I think; and this is what I want to know/have to find out yet) this is because in Graph 1 I have set my subwoofer on VARIABLE FREQUENCY control which means (according to my manual) that the PHASE KNOB of my subwoofer is active. I already had my phase setup correctly because I was always using this (VAR. FREQ. CONTROL) setting. In Graph 4 I ve put my switch on my subwoofer on FULL RANGE which means that the PHASE KNOB is NOT active anymore (according to my manual). This means I will have to do a new graph4-settings-measurement with first looking for the correct phase with the distance setting in my AVR. After finding the correct phase I will have to get the same graph as graph 1 if I am correct which also would mean that I understand my subwoofer settings (which is: switch on VAR. FREQ. CONTROL, VAR.FREQ.CONTROL KNOB on max (240) and PHASE KNOB on correct value *is the exact same* as switch on FULL RANGE so VAR.FREQ.CONTROL KNOB and PHASE KNOB not active).



> Since you are spread-sheet savy / I suggest that you make up a SS of all the permutations & combinations that you have tried to date / and then log the results for reference .


I m not THAT good with excel m8 



> Note : you have yet to try Johns ( aackthpt ) suggestion of running the system normally / ie; using the built in crossovers from the AVR .


will try that tonight



> Is there some reason you don't what to go down that road ?


reason is that I first want to understand what all settings (not the crossover!) in my AVR and on my SUBWOOFER do so I can first config. this all the right way. Only after this I m going to look into crossover and after that eq. my subwoofer with my Behringer FBQ1000.


----------



## EarlK

THX said:


> <snip>I did those tests to see what differences I would get in the results and not really to see if the bump would go away.<snip>


Fair Enough !

If you want to further explore what how things change on your outputs from your AVR ( with different mode selections ) then do what was suggested by JohnM & John ( which is feed your AVR a test signal and then bring back the relevant output from your AVR into REW to "see" & log the frequency changes ) . It is about the same setup as doing a soundcard calibration / but now including the AVR in the test circuit loop .

:sn:


----------



## aackthpt

THX-UltraII said:


> reason is that I first want to understand what all settings (not the crossover!) in my AVR and on my SUBWOOFER do so I can first config. this all the right way. Only after this I m going to look into crossover and after that eq. my subwoofer with my Behringer FBQ1000.


Earl, isn't he using the AVR crossovers whenever he's using the "full range" setting in the sub? Graph 4 or 8 would have been what I was suggesting, if I am reading his stuff right

UltraII, do you have only one seating position? For my setup it makes a huge difference whether I measure in the center (left-right) of the room or of center by ~18 inches. Response in the exact center is wonky and makes for sub setups that I don't like. But I have two chairs in the front row, if I measure from the center of one of them (the ~18 inches off center) the sound in the room is much more pleasant. So, you might try testing some other listening positions.

Signal coming out of the AVR is the most unadulterated signal we can verify, so that makes sense where to start. In response to your question, you can only capture one channel at a time with REW. You connect the output of your interface to the AVR as usual, and the input on the interface from the pre-out rather than the mic. You will have to do the sub pre-out and the left, or right, pre-out on separate runs, but it's totally repeatable so it will work fine.

Also, you _are_ running with Audyssey EQ off, yes?

After that your sweeps using the mic again but with sub only and main only is a good idea.

Another thing that is often done is to run sweeps with the mic up close (like less than 12 inches) away from the speaker or sub (best with gating, but you can get something close-ish without I think). That will help you know what the raw response is without much room influence. That would give you a better idea of whether the raw speaker response is causing any of the FR anomalies (at which point you should just probably go ahead and equalize them).

After that, you are probably into acoustics problems. A diagnostic you can do is, if your "bass traps" can be removed, put the mic in a corner and run sweeps without/with them in place. That will tell you real quick-like how effective they are. Can you outline what your "bass traps" are?


----------



## aackthpt

Here is the sub output directly from my Marantz SR4002 using an 80Hz crossover, for reference. If it doesn't look something like this, something is probably rong.


----------



## EarlK

John said:


> <snip> Earl, isn't he using the AVR crossovers whenever he's using the "full range" setting in the sub? Graph 4 or 8 would have been what I was suggesting, if I am reading his stuff right. <snip>


A careful reading of the user manual might clear up the question ( OTOH, answers should be forthcoming by executing some "loopback" measurements from the AVR's outputs // which Sanders seems willing to pursue with REWs help ) .

Either way ( IMHO ), it's up to every owner of an AVR to figure out how the equipment they bought actually works . 

If that comprehension isn't possible through self-study, then there is always the  *HTS AVR ( receiver ) Forum* 



:sn:


----------



## aackthpt

EarlK said:


> // which Sanders seems willing to pursue with REWs help ).


... What's the matter, Colonel Sanders? Chicken???





 then Shift+3. :rofl:


----------



## EarlK

John, that mostly went over my head ( but don't bother clarifying ) .

:sn:


----------



## THX-UltraII

Not sure yet how to do the measurements with my AVR. Am I correct that I disconnect my ECM8000 and turn off my amplifier and only have to turn on my AVR? And I connect the main LEFT or RIGHT front pre-out to the 1/4'' jack line in of the Tascam 122 MKII and that s it?


----------



## EarlK

Sander said:


> Am I correct that I disconnect my ECM8000 and turn off my amplifier and only have to turn on my AVR? And I connect the main LEFT or RIGHT front pre-out to the 1/4'' jack line in of the Tascam 122 MKII and that s it?



Yep ! It's a lot like doing a soundcard calibration but now including the AVRs' pre-amp within the loopback circuit ( just don't include amplifiers ) .

For the sake of safety ( & developing some "best practices" for loopback measurements ) , turn off the 48Volt phantom supply on your soundcard ( though I doubt that it's present on your line level input jack / at least it shouldn't be ) .

:sn:


----------



## aackthpt

Yes, you disconnect the mic altogether. If you use a separate amp from the AVR it can be off (in fact it will be disconnected from the AVR). The jacks on the front panel are not pre-outs, they are inputs to your AVR. Just send the signal to the AVR as you have been (perhaps let us know how). Have the AVR in a typical mode like "stereo". Connect the left or right pre-out to the jack line in of the Tascam for the main channel sweep. Switch that (on the AVR) to the sub-out rather than left or right out. Do "check levels" as usual. Run a sweep as usual. Output from the sub out should look like the picture in the link I posted.


----------



## THX-UltraII

> Yes, you disconnect the mic altogether. If you use a separate amp from the AVR it can be off (in fact it will be disconnected from the AVR).


check



> Just send the signal to the AVR as you have been (perhaps let us know how).


At this moment I have the Right RCA output of the Tascam (on the rear of the Tascam) connected to the Right+Left aux input of my AVR. Do I leave it this way?



> Have the AVR in a typical mode like "stereo". Connect the left or right pre-out to the jack line in of the Tascam for the main channel sweep. Switch that (on the AVR) to the sub-out rather than left or right out. Do "check levels" as usual. Run a sweep as usual. Output from the sub out should look like the picture in the link I posted.


So I first run a measurement with the Left (or Right) pre-out of my AVR connected to the Jack Line In (Left or Right) of the Tascam and after that run a measurement with the Sub pre-out of my AVR connected to the Jack Line In (Left of Right) of the Tascam?
Correct?


----------



## aackthpt

THX-UltraII said:


> At this moment I have the Right RCA output of the Tascam (on the rear of the Tascam) connected to the Right+Left aux input of my AVR. Do I leave it this way?
> 
> So I first run a measurement with the Left (or Right) pre-out of my AVR connected to the Jack Line In (Left or Right) of the Tascam and after that run a measurement with the Sub pre-out of my AVR connected to the Jack Line In (Left of Right) of the Tascam?
> Correct?


You would be better off for our purposes only connecting to the right in jack or the left in jack depending which channel you are going to be measuring. You will get much better results with measurement of one channel playing at a time, or else you get confounding combining effects between the two channels. In actual fact it probably doesn't matter for this test of the AVR, but it will matter when you get back to tests using the speakers.

Second part is entirely correct on the [REW] input side.


----------



## THX-UltraII

> You would be better off for our purposes only connecting to the right in jack or the left in jack depending which channel you are going to be measuring. You will get much better results with measurement of one channel playing at a time, or else you get confounding combining effects between the two channels. In actual fact it probably doesn't matter for this test of the AVR, but it will matter when you get back to tests using the speakers.


I don t understand what you are saying here John. The output of the Tascam is RCA and (of course) the AUX INPUT of my AVR is also RCA but you are talking about jacks. Am I missing something? But for the testing I will be doing I don t need to connect the output of the Tascam to the aux input of my AVR right?



> Second part is entirely correct on the [REW] input side.


And what info will I need? Just 2 measurements: one with crossover at 80 and running the R pre-out of my AVR to the R jack input of the Tascam and one measurement with the crossover also at 80 and running the SUB pre-out of my AVR to the jack input of the Tascam?


----------



## EarlK

I'm confident John is talking about your RCA phono plugs ( "jacks" as he called them ) .




Wikipedia said:


> <snip> in the UK, the terms *jack plug* and *jack socket* are commonly used for the respective male and female TRS connectors.[2] In the US, a stationary (more fixed) electrical connector is called a "jack".[3][4] The terms *phone plug *and *phone jack* are sometimes used to refer to TRS connectors,[5] but are also sometimes *used colloquially* to refer to RJ11 and older telephone plugs and the corresponding jacks that connect wired telephones to wall outlets (*the similar terms phono plug and phono jack *(or in the UK, phono socket) *refer to RCA connectors *common in consumer HiFi and Audio Visual equipment). *In conversation, *the diameter is often added to specify which size — quarter-inch phone plug or 3.5 mm phone jack for the unbalanced two-channel three-contact version, and balanced TRS jack or TRS phone plug for the balanced one-channel three-contact version. <snip>


Condensed ; "Jack" has almost lost all real meaning through it's inclusion in  *slang terms*  .



> But for the testing I will be doing I don t need to connect the output of the Tascam to the aux input of my AVR right?


Yes, you need to send signal from the RCA out ( on the soundcard ) to the RCA input on the AVR ( to get signal into that AVR ) .




> And what info will I need? <snip>


- You want to find out how all the different settings ( within your AVR ) change the frequency content of the signals outputted to your main speakers and your sub outs . 
- You have at least 2 relevant outputs ( a "Main Speaker" left or right out and the subwoofer out ) and switches on the AVR offering multiple choices, so (based on the laws of *Permutations & Combinations* ), that will generate more than 2 relevant measurements ( it's up to you to figure out how many ) .

:sn:


----------



## THX-UltraII

EarlK said:


> I'm confident John is talking about your RCA phono plugs ( "jacks" as he called them ) .
> 
> 
> 
> 
> Condensed ; "Jack" has almost lost all real meaning through it's inclusion in  *slang terms*  .
> 
> 
> 
> Yes, you need to send signal from the RCA out ( on the soundcard ) to the RCA input on the AVR ( to get signal into that AVR ) .
> 
> 
> 
> 
> - You want to find out how all the different settings ( within your AVR ) change the frequency content of the signals outputted to your main speakers and your sub outs .
> - You have at least 2 relevant outputs ( a "Main Speaker" left or right out and the subwoofer out ) and switches on the AVR offering multiple choices, so (based on the laws of *Permutations & Combinations* ), that will generate more than 2 relevant measurements ( it's up to you to figure out how many ) .
> 
> :sn:




thanks. This clears it up for me even more. But why do I have to feed the Tascam output to my AVRs input when I want to measure my AVR? I m only going to measure the output of my pre-outs. Or am I missing something here? And as for measurements I want to know how my AVRs pre-outs react on different AVR settings, ecspecially when I change crossover settings; I assume I only have to do 0-approx 300Hz measurements right?


----------



## EarlK

> But why do I have to feed the Tascam output to my AVRs input when I want to measure my AVR?


Think about the content of your question ( for about 24 hrs ) and then post again .

:sn:


----------



## THX-UltraII

EarlK said:


> Think about the content of your question ( for about 24 hrs ) and then post again .
> 
> :sn:


 No serieus, Earl. I just don t get it. I want to measure the OUTPUT of my AVR right. Of course I feed the Tascams input with the pre-outputs of my AVR (a signal that is generated by my AVR goes to the Tascam). Why would I need to OUTPUT something to the INPUT of my AVR than??

EDIT: 
DUH!!! REW generates a signal that goes to my Tascam. OF COURSE my Tascam need to feed this signal to my AVR first so my AVR can output it through it s pre-outs back to the Tascam. That s why you stated earlier in this thread that it is a loop.


----------



## EarlK

Glad it didn't take 24 hrs for you to figure that out .

Try thinking things through a bit more before committing your thoughts to print .

:sn:


----------



## aackthpt

THX-UltraII said:


> That's why you stated earlier in this thread that it is a loop.


Consider that if this test is REW->interface(output side)->AVR->interface (input side)->REW
then a normal room test is
REW->interface(output side)->AVR->speaker->room->microphone->interface (input side)->REW

The truth is that they are both loops, and what we are suggesting is for you to analyze individual parts of the bigger loop so that you may better understand what effects are created by which part, and therefore come to a better understanding how it works overall.


----------



## THX-UltraII

I wil do the measuerements this weekend.

John, I owe you some information you requested earlier in this thread.

- I have two seating positions. The one I m doing the measurements at is the main seat, the others from the wife . Changing listening positions will be (very) hard because I have a special build in D-Box system.

- Audessey EQ is OFF indeed

- will run sweeps with fronts only and sub only this weekend too

- will run swees with the mic close to the speakers too this weekend

- bass traps are enormous and extremely heavy and my back will not like it if I move them 
Here s a detailed discription of the acoustic equipment I m using:
- The 3 very big MDF basstraps I own have a very big cabinet and they take good care of the reverberation time under 100Hz. They are located in the back wall of my HT room (it is always difficult to contain the reverberation time at those frequencies). I will post pictures of them this weekend.
- My ceiling and 2 of my walls are 100% covered with Sombra-D panels http://www.ecophon.com/en/Product-Web/Sombra/Sombra-Ds/
- I have 25 small panel absorbers for the big heights in my room to prevent flutter echo http://www.soundscapes.nu/ng_flat.htm
- In the front of my room the are 2 GIK Acoustics Monster Traps installed http://www.gikacoustics.com/gik_monster_bass_traps.html
- In the upper corners of my room there are 2 Auralex LENRD Bass Traps installed http://www.auralex.com/bass_traps_lenrd/bass_traps_lenrd.asp
- All my walls next to the speakers have big diffuser panels installed on them http://www.soundscapes.nu/rb_dif.htm


----------



## aackthpt

LOL, you don't owe us a reply but it may help figure out what is going on is all. The main reason I ask is that some people build 2" absorber panels and then call them "bass traps". It sounds like you have a more proper job done in general. My experience is that LENRDs don't do much (though MegaLENRDs no doubt do). However it's always good to see someone who has diffusers :T. Also if you have MDF bass devices I bet those are Varitunes? If so, then that is *awesome*.

You said before that professionals did the acoustic design--did they come test the room afterward, but now you have changed your setup?


----------



## THX-UltraII

I ll come back later tonight on your reply John but I m too excited what you can make of some first AVR measurements I just did.

The measurements are done with the RIGHT PRE-OUT of my AVR so the a FRONT CHANNEL. I ve made 10 measurements with all measurements with same AVR settings (SMALL, LFE mode LFE) but 10 different crossovers: 40, 60, 80, 90, 100, 110, 120, 150, 200 and 250.

Here is the attachment


----------



## THX-UltraII

And here are 10 measurements with the same 10 AVR settings but with the SUB PRE-OUT connected to the Tascams RIGHT LINE INPUT


----------



## aackthpt

THX-UltraII said:


> I ll come back later tonight on your reply John but I m too excited what you can make of some first AVR measurements I just did.


I'd say it looks about like I'd expect. Perhaps Earl will have more to say about it, or something to point out. But it looks like you're doing it right! I look forward to seeing the sub-out results.

Hopefully this will help you understand what the various modes of your AVR are doing. :T


----------



## aackthpt

THX-UltraII said:


> And here are 10 measurements with the same 10 AVR settings but with the SUB PRE-OUT connected to the Tascams RIGHT LINE INPUT


Looks normal in the crossover region but from 20Hz down to 5Hz it rises by 15dB, which just made me realize--you need to run with NO MIC/METER CAL active when you do this, because it is not in the chain.


----------



## Rakkasan Trooper

Good lord men...I did not know I needed to speak a foreign language on this forum. I can see that I have my work cut out for me...


----------



## THX-UltraII

So this is what the subwoofer and main looks like with a co set at 80. Why is the crossover than 65 here? And this is no explanation for the bump in the 90-140 area I have right? So that bump must be comming from something else then? (settings or room?)


----------



## Barleywater

This is measurement of AVR, so no room involved. Remove mic/meter cal. Bump is not so much in bigger picture....Extending sweep to 600Hz, perhaps full range for mains output may clarify this. Overlays view shows crossover at 65Hz. Subwoofer crossover appears to be 24dB/octave slope, mains appear to be 12dB/octave slope.


----------



## THX-UltraII

did some AVR measuring again (pic you see are 2 graphs combined: sub pre-out and right main pre-out) but without the mic cal. file. 

pic 1: crossover 40
pic 2: crossover 60
pic 3: crossover 80
pic 4: crossover 90
pic 4: crossover 100
pic 5: crossover 110

What does these graphs tell me?


----------



## THX-UltraII

And here is the mdat file:

(I cannot upload a 32mb mdat file)


----------



## EarlK

Good to see you making progress ( in your education about how things work ) .



THX said:


> What does these graphs tell me?


They nicely display ( by happy accident ) that all crossover points are relative to the absolute levels of the 2 component parts ( ie; subs + mains ) .

As an exercise , repeat a couple of these measurements , but when it is time to send signal ( & swap cables to measure the subwoofers' output from the AVR ), reduce REWs drive level by 3 db ( within the preferences window ) . 

Once you overlay the 2 parts ( sub with mains ) you'll see that the electronic crossover point has now shifted to the left .

Repeat, but this time raise the drive level by 3 db ( when measuring the AVRs' sub-out ) and you'll see the electronic crossover point has now shifted to the right .

Please post your results for these variations .

:sn:


----------



## Barleywater

Oops! No file. Anyway, I further examine previous file: The subwoofer crossover appears to be Linkwitz-Riley 24dB/octave (L-R24) low pass filter at 80Hz. The mains crossover appears to be Butterworth 2nd order filter also at 80Hz. Gain difference between the two channels is about 1.7dB. This analysis was performed by porting impulse responses into Cool Edit Pro and synthesizing matching filters. 

Linkwitz-Riley filter is formed by cascading two stages of a Butterworth filter. Since the subwoofer likely has somewhat flat response well beyond 80Hz, the L-R24 is used in effort to get 24dB/octave roll off. Typical sealed cabinet mains speakers of the small floor standing/larger bookshelf styles have acoustic roll off in this region of about 12dB/octave, and with a whole lot of luck and knob twiddling by the user combines with 12dB/octave Butterworth 12dB/octave filter, resulting in flattish response through the crossover region.... 

Best to start measuring speakers and picking flavor, or you risk eventually ending up like me, knowing way too much, and listening way too little.

Andrew


----------



## aackthpt

THX-UltraII said:


> What does these graphs tell me?


The short version of what Barley said is that everything is working properly per the THX scheme. Secondly it should probably be obvious that your FR as being sent by the AVR is fine. Earl's experiment may reveal a bit more.

Given all that, consider our earlier discussion of the signal chain. What does this tell you?


----------



## THX-UltraII

EarlK said:


> Good to see you making progress ( in your education about how things work ) .
> 
> 
> 
> They nicely display ( by happy accident ) that all crossover points are relative to the absolute levels of the 2 component parts ( ie; subs + mains ) .
> 
> As an exercise , repeat a couple of these measurements , but when it is time to send signal ( & swap cables to measure the subwoofers' output from the AVR ), reduce REWs drive level by 3 db ( within the preferences window ) .
> 
> Once you overlay the 2 parts ( sub with mains ) you'll see that the electronic crossover point has now shifted to the left .
> 
> Repeat, but this time raise the drive level by 3 db ( when measuring the AVRs' sub-out ) and you'll see the electronic crossover point has now shifted to the right .
> 
> Please post your results for these variations .
> 
> :sn:


I don t think that I need to post new graphs. Let me try and see if I understand:
When lowering the subwoofer level (REW drive level from -12 to -15) the line from the subwoofer drops (overall) but the level line from the main R stays the same so the crossoverpoint is lowered than. The other way, when increasing the REW level from -12 to -9, the subwoofer overall line increases and the main R line stays the same so that means the crossover (on paper) goes to a higher value.

But what I still do not understand is that with the measurements I did all the levels are measured the same so the crossover for the setting AVR-80-crossover should be exactly 80 right? So why is it 65 (on paper) than?


----------



## THX-UltraII

aackthpt said:


> The short version of what Barley said is that everything is working properly per the THX scheme. Secondly it should probably be obvious that your FR as being sent by the AVR is fine. Earl's experiment may reveal a bit more.
> 
> Given all that, consider our earlier discussion of the signal chain. What does this tell you?


This tells me that the bump in the 90-140 area is due to the room and not because of my settings in my AVR


----------



## Barleywater

Your room is not in any way connected to measurements of you AVR when it is hard wired to the sound card. No microphone, no speakers, no room....

The bump is a matter of how well the crossover was (wasn't) implemented in your AVR. A THX EQ curve may also be involved.

The apparent cross at 65Hz "on paper" is entirely due to mixing of two different types of crossover filter, and that the filters are at two different relative amplitudes.

Andrew


----------



## aackthpt

THX-UltraII said:


> But what I still do not understand is that with the measurements I did all the levels are measured the same so the crossover for the setting AVR-80-crossover should be exactly 80 right? So why is it 65 (on paper) than?


You are reading "the point at which the lines cross" as the crossover frequency, which is not the reference used when engineers define filters. Consider what Barley said, THX (and by default, pretty much everyone else, even if it doesn't work properly because many have ported rather than sealed mains--though since you have a THX array you have sealed mains) uses a Linkwitz-Riley on the subwoofer side (because the sub typically has useful bandwidth extended well past the crossover frequency), but uses a lower-order filter on the mains side, which is supposed to combine with the rolloff of the mains (which are designed this way in a THX array) to give the actual acoustical rolloff the Linkwitz-Riley value, which theoretically results in the best crossover region.



> This tells me that the bump in the 90-140 area is due to the room and not because of my settings in my AVR


Possibly, but possibly not. Remember the chains?
AVR test: REW->interface(output side)->AVR->interface (input side)->REW
Overall : REW->interface(output side)->AVR->speaker->room->microphone->interface (input side)->REW

Assuming your interface is probably calibrated, and that you have a decent microphone calibration (I don't think we discussed that), there are actually two differences between these tests: speakers and room. Therefore the data we have says it's likely that one of those, or some interaction between them, is causing any issues you may have.

Also, does this help you draw any conclusions on whether you should be using "full range" on the sub and "small" for the speakers and such, all the configuration items we have discussed before?


----------



## EarlK

THX said:


> This tells me that the bump in the 90-140 area is due to the room and not because of my settings in my AVR


That *would be* a reasonable conclusion to make *if* you are *using the same settings *( in the AVR ) that you just measured .

Are you ?

If not , measure ( using REW's loopback setup ) the AVR settings that you do use ( ie; both the "Sub-Out" & the "Mains" ) .

:sn:

PS : Here's a pic of how your sub measures using AVR settings as you had them set a week ago ( from within your 2nd .mdat file located on the first page of this thread )


----------



## THX-UltraII

> You are reading "the point at which the lines cross" as the crossover frequency, which is not the reference used when engineers define filters. Consider what Barley said, THX (and by default, pretty much everyone else, even if it doesn't work properly because many have ported rather than sealed mains--though since you have a THX array you have sealed mains) uses a Linkwitz-Riley on the subwoofer side (because the sub typically has useful bandwidth extended well past the crossover frequency), but uses a lower-order filter on the mains side, which is supposed to combine with the rolloff of the mains (which are designed this way in a THX array) to give the actual acoustical rolloff the Linkwitz-Riley value, which theoretically results in the best crossover region.


understand now. thxz



> Possibly, but possibly not. Remember the chains?
> AVR test: REW->interface(output side)->AVR->interface (input side)->REW
> Overall : REW->interface(output side)->AVR->speaker->room->microphone->interface (input side)->REW
> 
> Assuming your interface is probably calibrated, and that you have a decent microphone calibration (I don't think we discussed that), there are actually two differences between these tests: speakers and room. Therefore the data we have says it's likely that one of those, or some interaction between them, is causing any issues you may have.


also understand this now (that bump can also be caused by speakers+room and not only room). 
I use a decent micrphone Cross Spectrum calaibrated. I use the 'narrow_band_response_0_degree.frd' file that came with the mic. and I placed the mic. on an exact HORIZONTAL position and listening position at exact ear height.



> Also, does this help you draw any conclusions on whether you should be using "full range" on the sub and "small" for the speakers and such, all the configuration items we have discussed before?


it is this entire thread and ecspecially you and Earl from which I ve learned how to config it now: 
Speakers SMALL, LFE mode on LFE only, LPF of LFE on 120, subwoofer on FULL RANGE setting (so phase and freq. range on subwoofer are disabled) and configed the distance setting in my AVR to get the right phase between subwoofer and main.


----------



## THX-UltraII

> That *would be* a reasonable conclusion to make *if* you are *using the same settings *( in the AVR ) that you just measured .
> 
> Are you ?


yes, I am


----------



## THX-UltraII

allright, now that I have found the correct settings for my subwoofer and AVR ( (only thing to play with yet is set AVR crossover to different value) it was time for some new measurements. I did 3 measurements with the crossover at 80:

1. R MAIN+SUB
2. SUB ONLY
3. R MAIN ONLY

I think, and correct me if I m wrong, I first need to find the (approx) correct volume for my subwoofer. The volume on my subwoofer is quite low when I did these measurements but I did this because when I raised the volume of the subwoofer any further then this the 20 to approx. 100Hz area got an overall to big hump compared to the 100Hz-20000Hz area. I assume the overall total area (from 20-20000) has to be in the 'same volume range'. The 'problem' I see for now (NOT yet looking at bumps or dips) is that the subwoofer volume drops quite fast from 40Hz and more while the volume from the main channel drops almost nothing! (I see it only drop s little from 30Hz and less. (which still keeps raising question with me because WHY can this be while my crossover is set at 80! sorry I still don t get it guys ).

Allright, what can you guys make for conclusion with these new measurements to help me understand better? And what is recommended for my next step BEFORE I m going to make changes with my Behringer equaliser (which is still in bypass mode atm)? Should I play with the volume of my subwoofer and/or with the co setting in my AVR?

ps. All of the graphs have 1/3 smoothing


----------



## THX-UltraII

and I forgot the mdat file:


----------



## EarlK

Try raising the crossver point to 120 hz to see if both slopes ( for Mains & Subs ) shift upwards .

:sn:


----------



## acoustat6

Hi THX-ultra, Does it hurt your ears to listen to the test at such a high level? I mean 140Db!!! WOW thats loud.

Thanks,
Bob


----------



## aackthpt

THX-UltraII said:


> The 'problem' I see for now (NOT yet looking at bumps or dips) is that the subwoofer volume drops quite fast from 40Hz and more while the volume from the main channel drops almost nothing! (I see it only drop s little from 30Hz and less. (which still keeps raising question with me because WHY can this be while my crossover is set at 80! sorry I still don t get it guys ).


I fail to see why this is a problem. The overall response is decent, or not entirely unexpected, actually. Earl's suggestion to try different crossover frequencies to see what produces the best result with your system is a good one though. Note that optimal phase (distance) for sub may be slightly different for different crossover settings (shouldn't be much different, and depends on the fineness of the distance controls in that AVR).



> Allright, what can you guys make for conclusion with these new measurements to help me understand better? And what is recommended for my next step BEFORE I m going to make changes with my Behringer equaliser (which is still in bypass mode atm)? Should I play with the volume of my subwoofer and/or with the co setting in my AVR?


First, I suggest you read items linked from the REW Information Index, particularly the first two of the technical articles. Note there are special features in the equalization section of REW to implement this. Many people prefer a response that is rising toward the LF. You may find that you do, too.

After finding the best crossover frequency, there are sort of two paths you can go down, acoustical or equalization. Since it sounds as though you don't want to make acoustical changes, you might as well start attempting some EQ. I would urge you to take measurements in each listening position before and after any EQ. Make sure to view your results (alll of them) at various smoothing levels. 1/3 is generally appropriate for overall balance across the entire audible range, but is typically too much smoothing for LF. You would also do well to read the "minimum phase" page of the REW help as many times as it takes to fully understand it.

The sub is doing you well, BTW... less than 10% THD down to 19 Hz... not bad. :T

Mad props to JohnM for the new distortion features. :T:T


----------



## aackthpt

Forgot to add this part. Get the system set up as well as it can be with Audyssey off. Make sure you write down all the settings, then re-set up Audyssey. If it improves things, use it--if not then don't.

Often the sort of pre-calibration / setup helps Audyssey do a better job than when first, as far as I can tell from other threads.

acoustat, I wouldn't assume his sweep is actually at 140 dB SPL. He simply may not have set the REW SPL meter to an external reference--and this is fine for nearly all of our purposes as we really care about relative levels between things, not the absolute level. In fact the typical microphones we use for this stuff cannot record at those levels without distorting--e.g. the page for the Dayton EMM-6 says "Max SPL for 1% THD @ 1 kHz: 127 dB". Since his last measurement did not have much THD on it, I highly doubt he was measuring at 140 dB SPL.


----------



## aackthpt

Also, I believe he said he had FV15HP for subwoofing. If you look at its distortion figures, even though those are in 2pi space, I bet it couldn't produce 140dB in a room without truly massive amounts of THD--if it even could produce that at all.


----------



## EarlK

THX said:


> and I forgot the mdat file:


There's a huge problem with that particular mdat file . You were using a bogus soundcard calibration file and it has drastically skewed the way traces are represented on the screen ( though all the IRs remain intact ).

See below ; 1st pic is with skewed response , 2nd pic has had the bad SC calibration file removed ( by exporting & re-importing the IR ) .

:sn:


----------



## THX-UltraII

EarlK said:


> There's a huge problem with that particular mdat file . You were using a bogus soundcard calibration file and it has drastically skewed the way traces are represented on the screen ( though all the IRs remain intact ).
> 
> See below ; 1st pic is with skewed response , 2nd pic has had the bad SC calibration file removed ( by exporting & re-importing the IR ) .
> 
> :sn:


What are IRs? And what do I have to do? Do a re-callibration of my soundcard?


----------



## THX-UltraII

EarlK said:


> Try raising the crossver point to 120 hz to see if both slopes ( for Mains & Subs ) shift upwards .
> 
> :sn:


I Earl will but first see my reply above this one.


----------



## THX-UltraII

acoustat6 said:


> Hi THX-ultra, Does it hurt your ears to listen to the test at such a high level? I mean 140Db!!! WOW thats loud.
> 
> Thanks,
> Bob
> If the first 100db suck, why continue?


I m 100% sure it is NOT 140dB


----------



## THX-UltraII

> I fail to see why this is a problem. The overall response is decent, or not entirely unexpected, actually. Earl's suggestion to try different crossover frequencies to see what produces the best result with your system is a good one though. Note that optimal phase (distance) for sub may be slightly different for different crossover settings (shouldn't be much different, and depends on the fineness of the distance controls in that AVR).


How do I re-check the phase after choosing a different crossover? Just play a tone again and see where I get the highest value on my dB meter with both the main channels and sub running but now choose to play a 120Hz file (of course for 120 crossover) instead of a 80Hz file? ps. I can set 0.01m values for distances (so 4.21m, 4.22m, 4.23m and so on) so this is pretty narrow.



> First, I suggest you read items linked from the REW Information Index, particularly the first two of the technical articles. Note there are special features in the equalization section of REW to implement this. Many people prefer a response that is rising toward the LF. You may find that you do, too.


I ll read this stuff tonight John.



> After finding the best crossover frequency, there are sort of two paths you can go down, acoustical or equalization. Since it sounds as though you don't want to make acoustical changes, you might as well start attempting some EQ. I would urge you to take measurements in each listening position before and after any EQ. Make sure to view your results (alll of them) at various smoothing levels. 1/3 is generally appropriate for overall balance across the entire audible range, but is typically too much smoothing for LF. You would also do well to read the "minimum phase" page of the REW help as many times as it takes to fully understand it.


check!



> The sub is doing you well, BTW... less than 10% THD down to 19 Hz... not bad. :T


Eh,,,,?


----------



## THX-UltraII

aackthpt said:


> Also, I believe he said he had FV15HP for subwoofing. If you look at its distortion figures, even though those are in 2pi space, I bet it couldn't produce 140dB in a room without truly massive amounts of THD--if it even could produce that at all.


this technical talk is out of my league . Can you descibe it in 'simple' like you do all the time so I can understand?


----------



## EarlK

THX said:


> What are IRs? And what do I have to do? Do a re-callibration of my soundcard?


Sorry for the jargon .

(a) IRs = Impulse Response 

(b) Reload one of your older soundcard cailbration files ( from a week ago , for instance ), they were fine .

(c) If you can't find your old calibration file, make a new one . 
- It's better to go without a calibration file loaded , than use the one I just showed above .

:sn:


----------



## THX-UltraII

Is this better?


----------



## EarlK

> Is this better?


Yes !

:sn:


----------



## THX-UltraII

Allright. Here the new (better) one:

Graph 1: crossover 80, MAIN RIGHT+SUB
Graph 2: crossover 80, MAIN RIGHT ONLY
Graph 3: crossover 80, SUB ONLY

What can you tell me now with this new information?


----------



## EarlK

I can tell you that things are back to where they should be ( therefore now you can move forward & search for a better Xover point ).

Now try raising your crossover point to 120hz ( & post the results ).

:sn:


----------



## THX-UltraII

EarlK said:


> I can tell you that things are back to where they should be ( therefore now you can move forward & search for a better Xover point ).
> 
> Now try raising your crossover point to 120hz ( & post the results ).
> 
> :sn:


Im at work now but will post them tomorrownight. thxz for now earl


----------



## aackthpt

Good catch on that earl, thanks!

THX, basically I was saying that your subwoofer can't get as loud as 140 DB inside based on test results outside. 2pi space means outside which is how the data-bass that I linked to measures all the subs (because it is the industry standard way to test them). THD is total harmonic distortion which gets very high when you try to play a sub too loud.

So there was evidence both on the micro phone and speaker side that you weren't running at 140dB SPL


----------



## THX-UltraII

aackthpt said:


> Good catch on that earl, thanks!
> 
> THX, basically I was saying that your subwoofer can't get as loud as 140 DB inside based on test results outside. 2pi space means outside which is how the data-bass that I linked to measures all the subs (because it is the industry standard way to test them). THD is total harmonic distortion which gets very high when you try to play a sub too loud.
> 
> So there was evidence both on the micro phone and speaker side that you weren't running at 140dB SPL


thxz for your reply. But whats the cause of my too high results? I know it does not matter for the freq. response to read but I just want to know what to do to get the right/actual dB values after a measurement


----------



## THX-UltraII

THX-UltraII said:


> How do I re-check the phase after choosing a different crossover? Just play a tone again and see where I get the highest value on my dB meter with both the main channels and sub running but now choose to play a 120Hz file (of course for 120 crossover) instead of a 80Hz file? ps. I can set 0.01m values for distances (so 4.21m, 4.22m, 4.23m and so on) so this is pretty narrow.


Earl or John, can you come back on the above too?


----------



## aackthpt

deleted


----------



## aackthpt

THX-UltraII said:


> thxz for your reply. But whats the cause of my too high results? I know it does not matter for the freq. response to read but I just want to know what to do to get the right/actual dB values after a measurement


The cause of the too-high reading for absolute SPL is that you have not calibrated the SPL meter in REW. You need to use an SPL meter for this if you own one, or else borrow one from a friend. It's a "nice to have" for our purposes now, and not absolutely required. The page in the REW online help explaining how to do this is this one right heah.


----------



## aackthpt

THX-UltraII said:


> THX-UltraII wrote:
> How do I re-check the phase after choosing a different crossover? Just play a tone again and see where I get the highest value on my dB meter with both the main channels and sub running but now choose to play a 120Hz file (of course for 120 crossover) instead of a 80Hz file? ps. I can set 0.01m values for distances (so 4.21m, 4.22m, 4.23m and so on) so this is pretty narrow.
> 
> Earl or John, can you come back on the above too?


There are several options for checking the phase:
1. Changing the distance while you run sweeps (or use the spectrum/RTA display as described below) to see what nets the best FR. Not really the fastest or best method, but easy for most people to understand.
2. Using the "nulling method". Invert the sub, and adjust the distance while running sweeps or watching an unsmoothed spectrum display with white noise playing, or RTA display with pink noise playing, and create the maximum depth null possible at the crossover point, then just invert the sub back.
3. Use the excess group delay plot, if it's flat enough to be able to tell that the sub is early or late, as shown in the group delay section of the REW help.
4. By manually viewing the impulse responses of sweeps taken in tight ranges around the crossover frequency, and aligning the waveforms by figuring out the time difference between the two and calculating the corresponding distance. Probably the most precise way, but also the most difficult to understand. This method is explained in this thread, which I only recently found thanks to Earl's mention of it in a different thread. One of the originators of the method also write a concise overview in this thread.

I'm actually going to implement a lot of the ideas we are discussing in this thread as soon as I get a chance to tweak in my own theatre. :T


----------



## THX-UltraII

aackthpt said:


> The cause of the too-high reading for absolute SPL is that you have not calibrated the SPL meter in REW. You need to use an SPL meter for this if you own one, or else borrow one from a friend. It's a "nice to have" for our purposes now, and not absolutely required. The page in the REW online help explaining how to do this is this one right heah.


I own a Velleman AVM2050 Analog Sound Level Meter. 
So to calibrate the SPL in REW (correct where I m wrong):

1. Disconnect the ECM8000
2. Go to the preferences and remove my ECM8000 file and check the C weighing box.
3. Open REW SPL and press CALIBRATE
4. choose 'Use REW speaker cal pink noise'
5. Read what my SPL meter says (SPL meter on listening position at ear height in 0 degrees??)


----------



## THX-UltraII

> 1. Changing the distance while you run sweeps (or use the spectrum/RTA display as described below) to see what nets the best FR. Not really the fastest or best method, but easy for most people to understand.


What s FR? And with this you just mean to take a measurement, after this check the 'ALL SPL' graph, after this take a new measurement with a change made in the distance setting and check ALL SPL again. Do this untill I get the 'best' most flat curve.
Correct? 



> 2. Using the "nulling method". Invert the sub, and adjust the distance while running sweeps or watching an unsmoothed spectrum display with white noise playing, or RTA display with pink noise playing, and create the maximum depth null possible at the crossover point, then just invert the sub back.


I can t invert the phase (remember, my subwoofer is now in the FULL RANGE setting which disabled all settings on the subwoofer itself). But I can do it like I do maybe? Which is:
Run a 80Hz tone (or 120Hz tone when the co is 120??) and make sure that both subwoofer and mains are playing the signal at an approx equel level. Then adjust the distance setting of the AVR untill my SPL has the HIGHEST possible value.



> 3. Use the excess group delay plot, if it's flat enough to be able to tell that the sub is early or late, as shown in the group delay section of the REW help.


I ll look into this tonight



> 4. By manually viewing the impulse responses of sweeps taken in tight ranges around the crossover frequency, and aligning the waveforms by figuring out the time difference between the two and calculating the corresponding distance. Probably the most precise way, but also the most difficult to understand. This method is explained in this thread, which I only recently found thanks to Earl's mention of it in a different thread. One of the originators of the method also write a concise overview in this thread.


Just read this but for now most of this is out of my league.


----------



## aackthpt

THX-UltraII said:


> I own a Velleman AVM2050 Analog Sound Level Meter.
> So to calibrate the SPL in REW (correct where I m wrong):
> 
> 1. Disconnect the ECM8000
> 2. Go to the preferences and remove my ECM8000 file and check the C weighing box.
> 3. Open REW SPL and press CALIBRATE
> 4. choose 'Use REW speaker cal pink noise'
> 5. Read what my SPL meter says (SPL meter on listening position at ear height in 0 degrees??)


1. wrong, it stays connected (how else is REW going to read the SPL??)
2. wrong, C weighting is set on your meter not in REW (it's already in REW)
3. correct
4. I would suggest trying both the speaker and subwoofer cal noises, and using the one that produces the most stable reading on your SPL meter
5. correct
6. Enter the number your handheld meter reads into REW where it asks for it (step 5 in the REW help)

Note that if you expect the values to be accurate, you will have to do this again each time you move the input gain knob on your audio interface, or if you change the levels in its driver or Windows. Anything that changes the gain on the input side will require you to redo this if you expect it to be accurate. Since it's a very quick process I do it every time I set up to take measurements along with checking levels.


----------



## aackthpt

THX-UltraII said:


> What s FR? And with this you just mean to take a measurement, after this check the 'ALL SPL' graph, after this take a new measurement with a change made in the distance setting and check ALL SPL again. Do this untill I get the 'best' most flat curve.
> Correct?
> 
> I can t invert the phase (remember, my subwoofer is now in the FULL RANGE setting which disabled all settings on the subwoofer itself). But I can do it like I do maybe? Which is:
> Run a 80Hz tone (or 120Hz tone when the co is 120??) and make sure that both subwoofer and mains are playing the signal at an approx equel level. Then adjust the distance setting of the AVR untill my SPL has the HIGHEST possible value.
> 
> I ll look into this tonight
> 
> Just read this but for now most of this is out of my league.


FR = frequency response. Yes that is exactly what I meant on this.

In my case I have a passive sub+amp so I could invert it by switching the connections to the sub cabinet for example. I was just going through the options, not necessarily saying all these options are viable for you. However, you probably could get the same effect by switching polarity of the speaker rather than the sub. The "highest level" setting is likely functionally equivalent to the first method.


----------



## THX-UltraII

aackthpt said:


> 1. wrong, it stays connected (how else is REW going to read the SPL??)
> 2. wrong, C weighting is set on your meter not in REW (it's already in REW)
> 3. correct
> 4. I would suggest trying both the speaker and subwoofer cal noises, and using the one that produces the most stable reading on your SPL meter
> 5. correct
> 6. Enter the number your handheld meter reads into REW where it asks for it (step 5 in the REW help)
> 
> Note that if you expect the values to be accurate, you will have to do this again each time you move the input gain knob on your audio interface, or if you change the levels in its driver or Windows. Anything that changes the gain on the input side will require you to redo this if you expect it to be accurate. Since it's a very quick process I do it every time I set up to take measurements along with checking levels.


1. ok
2. ok
3. ok
4. ok, but do I use C weighing SLOW or C weighing FAST?
5. ok
6. ok

Note: understood


----------



## THX-UltraII

aackthpt said:


> FR = frequency response. Yes that is exactly what I meant on this.
> 
> In my case I have a passive sub+amp so I could invert it by switching the connections to the sub cabinet for example. I was just going through the options, not necessarily saying all these options are viable for you. However, you probably could get the same effect by switching polarity of the speaker rather than the sub. The "highest level" setting is likely functionally equivalent to the first method.


I ve read somewhere that measuring the lowest level and then switch phase 180 degrees is easier and more accurate to do then the method I am using (find the highest level). So in my case I could do this by switching the speakercable from left to right (only on one side of course) and then look for the biggest dip in level of my dB meter when both main+sub is running and after that switch back my speaker cable?
But like I said before, for a 80 Xover I used a 80Hz tone, is it best to use a test tone corresponding when the Xover so 90Hz for 90Xover, 100Hz for 100Xover etc?


----------



## THX-UltraII

I also just found something JohnM has posted some time ago. Is short he says that getting sensible phase measurements can be tricky. He says that the best method is to use the REW RTA and make adjustments while watching the effect on the RTA. Use REW's "Pink PN" test signal, set the RTA for Rectangular window, no averaging, 64k RTA length. After this measure with the sub and one main speaker running. Adjust distance setting in AVR to see which gives the smoothest response through the crossover region.

Seems doable (yeah, I m learing)


----------



## aackthpt

THX-UltraII said:


> 4. ok, but do I use C weighing SLOW or C weighing FAST?


Use the slow response speed setting.


----------



## aackthpt

THX-UltraII said:


> I also just found something JohnM has posted some time ago. Is short he says that getting sensible phase measurements can be tricky. He says that the best method is to use the REW RTA and make adjustments while watching the effect on the RTA. Use REW's "Pink PN" test signal, set the RTA for Rectangular window, no averaging, 64k RTA length. After this measure with the sub and one main speaker running. Adjust distance setting in AVR to see which gives the smoothest response through the crossover region.
> 
> Seems doable (yeah, I m learing)


As you mentioned before, in theory the "maximum null" theory should be more accurate than the "smoothest FR" method. So I suggest you try both to find the smoothest FR with regular setup, and to find the biggest null with main speaker cable switched red/black. If the methods work, results should agree.

In truth, I haven't even done this myself. Last time I researched this the results said "as long as you don't have horn subs, use a measuring tape". Now that I know several ways to do it more accurately I plan to do this on my own system soonish. Although to some extent it will happen as I build out, as I am planning to replace my current sub with several DIY units.


----------



## THX-UltraII

> 2. wrong, C weighting is set on your meter not in REW (it's already in REW)


I have to come back on this one: What do you mean with that it s already in REW? I haven t checked the C weighing box in the settings because I thought I had to leave this box unticked when using a ECM8000


----------



## aackthpt

THX-UltraII said:


> I have to come back on this one: What do you mean with that it s already in REW? I haven t checked the C weighing box in the settings because I thought I had to leave this box unticked when using a ECM8000


You do leave it unticked. The one in preferences is for the characteristic of the measuring device so it can be accounted for (when not using a calibration curve that accounts for it).

What you need is the C-weighted meter to be matched by REW's SPL meter being run C-weighted. See the middle section of the meter capture on this page, the A/C/Z buttons are for weighting, it should automagically start with C-weighting active unless you have changed it.


----------



## THX-UltraII

hmmm, something is happening what I don t understand (AGAIN! ):
When I click on the SPL meter and calibrate and choose 'use REW speaker cal signal' I have to set my AVR on -22 to get 80dB on the (Velleman) SPL meter. But when I choose 'use REW subwoofer cal signal' I have to raise the volume of my amplifier to -2! to get 80dB on my SPL meter.:blink:
btw. when I choose the option 'use REW subwoofer cal signal' sound is comming from both my subwoofer and main right speaker. Isn t the sound supposed to come only from the subwoofer? (that why its called 'use REW subwoofer cal signal' isnt it?)


----------



## aackthpt

THX-UltraII said:


> hmmm, something is happening what I don t understand (AGAIN! ):
> When I click on the SPL meter and calibrate and choose 'use REW speaker cal signal' I have to set my AVR on -22 to get 80dB on the (Velleman) SPL meter. But when I choose 'use REW subwoofer cal signal' I have to raise the volume of my amplifier to -2! to get 80dB on my SPL meter.:blink:
> btw. when I choose the option 'use REW subwoofer cal signal' sound is comming from both my subwoofer and main right speaker. Isn t the sound supposed to come only from the subwoofer? (that why its called 'use REW subwoofer cal signal' isnt it?)


How are you sending the signal to the AVR? If you are feeding it analog in, then you can't control which speakers it goes to, the AVR controls it. Some sound gets past a crossover many octaves past the crossover frequency -- it just shouldn't be much.

As for the 20dB difference I'm not sure, but I don't think it matters. Like the SPL values coming from REW, the number on the AVR when you turn the volume dial doesn't really matter (unless you are concerned about THX reference level.... but I'm not--I'm sure I don't like to listen that loud and it just plain doesn't matter). Are the levels 20 dB different on the REW SPL meter also? If so there is probably no problem with anything. Again just use the most stable one (and wear appropriate hearing protection so you don't deafen yourself -- I do whenever I do any acoustical testing, actually).


----------



## THX-UltraII

aackthpt said:


> How are you sending the signal to the AVR? If you are feeding it analog in, then you can't control which speakers it goes to, the AVR controls it. Some sound gets past a crossover many octaves past the crossover frequency -- it just shouldn't be much.
> 
> As for the 20dB difference I'm not sure, but I don't think it matters. Like the SPL values coming from REW, the number on the AVR when you turn the volume dial doesn't really matter (unless you are concerned about THX reference level.... but I'm not--I'm sure I don't like to listen that loud and it just plain doesn't matter). Are the levels 20 dB different on the REW SPL meter also? If so there is probably no problem with anything. Again just use the most stable one (and wear appropriate hearing protection so you don't deafen yourself -- I do whenever I do any acoustical testing, actually).


I m sending the signal from the Tascam from the R rca output to the R rca aux input of my AVR.

I just did a new test and I disconnected the main right speaker when I chose the 'use REW subwoofer cal signal'. So now only my subwoofer was generating a signal when doing the SPL measurement. Now I can t even get 80dB on my SPL meter anymore. I really turned up the volume of my subwoofer until my HT room was shaking but I could not reach 80dB on the SPL meter at all......


----------



## THX-UltraII

And here are a lot of new measurements. I will post 10 .mdat files. All 10 single files contain 3 measurements which are a measurement with the MAIN ONLY, one with the MAIN+SUB and one with the SUB ONLY. The difference in all 10 .mdat measurements is that I did it for all 10 possible Xover settings which my AVR has: 40, 60, 80, 90, 100, 110, 120, 150, 200 and 250. I HAVE NOT changed the phase (distance) setting for each different Xover measurement so I hope (and think) that the little differences in the distance setting that is needed per Xover is not THAT important (of course I will check the phase when I choose the final Xover setting that I m going to use). 

What are the conclusions you can make from this John and Earl?

I checked them myself too of course and to me the one with the Xover at 250 looks the best of all to me (looks quitre perfect?) but a CO of 250 is not an option I want to use right? I have a feeling that one does not want to go higher than max. 100 for Xover? 

What can we make for conclusions now? Is my current seating position just no option or is it not THAT bad? 

ps. I will do new measurements from another seating position that MIGHT be possible to make. Will post (lot of) new measurements with this new measurming position tomorrow night. Or not if we/I can make something of the current seating position. (I have the Behringer of course but I only want to use it for the fnal tuning)


----------



## aackthpt

You forgot the attachment. Lulz.


----------



## planetc

THX-UltraII said:


> I really turned up the volume of my subwoofer until my HT room was shaking but I could not reach 80dB on the SPL meter at all......


Mine reads a little low with the sub too, I suspect that it's down to the meter in my case. If you calibrate the level on the mains then it should be accurate for the sub when you switch back to the 8000 as it's all relative.


----------



## EarlK

New Files ???



THX said:


> <snip> And *here are* a lot of new measurements. I *will post* 10 .mdat files. All 10 single files contain 3 measurements which are a measurement with the MAIN ONLY, one with the MAIN+SUB and one with the SUB ONLY. <snip>


I don't get it. Today, tomorrow, when ? :huh:

:sn:



THX said:


> What are the conclusions you can make from this John and Earl?


???


----------



## THX-UltraII

And the .mdat files of course


----------



## THX-UltraII

and the rest


----------



## EarlK

I'd try to find a way to make something like this work .

It means you have to find a mode ( within your AVRs speaker management system ) that applies the AVRs crossover onto your mains but not on the subs .

You use the subs built-in variable crossover instead .

*EDIT :* You can still run everything as you do currently . Just set the crossover point to 150hz ( for both mains & sub ) and then engage the subs own internal crossover and set it to @ 80 hz .


:sn:


----------



## THX-UltraII

EarlK said:


> I'd try to find a way to make something like this work .
> 
> It means you have to find a mode ( within your AVRs speaker management system ) that applies the AVRs crossover onto your mains but not on the subs .
> 
> You use the subs built-in variable crossover instead .
> 
> *EDIT :* You can still run everything as you do currently . Just set the crossover point to 150hz ( for both mains & sub ) and then engage the subs own internal crossover and set it to @ 80 hz .
> 
> 
> :sn:


Good idea Earl, I understand what I have to try and accomplish. 

But:
In the crossover settings of my AVR I have an 'ADVANCED CROSSOVER' option. My manual says this about the advanced crossover:
http://us.marantz.com/DocumentMaster/US/SR5005_U_EN_UG_v00.pdf

Advanced : Specify crossover frequency for each speaker.
• Front / Center / Surround / S.Back / Front Height : Select the speaker.
• 40Hz / 60Hz / 80Hz / 90Hz / 100Hz / 110Hz / 120Hz / 150Hz / 200Hz /
250Hz : Set the crossover frequency.
• “Crossover Freq.” can be set when the “Bass Setting” – “Subwoofer
Mode” (vpage 57) setting is “LFE+Main”, or when you have a speaker
that is set to “Small”.
• Always set the crossover frequency to “80Hz”. When using small
speakers, however, we recommend setting the crossover frequency to
a higher frequency.
• For speakers set to “Small”, sound below the crossover frequency
is cut from the sound output. The cut bass sound is output from the
subwoofer or front speakers.
• The speakers that can be set when “Advanced” is selected differ
depending on the “Subwoofer Mode” setting (vpage 57).
• When “LFE” is selected, speakers set to “Small” at “Speaker Config.”
can be set. If the speakers are set to “Large”, “Full Band” is displayed
and the setting cannot be made.
• If set to “LFE+Main”, this setting can be made regardless of the
speaker size.


Can I do something with this advanced crossover so I can leave my subwoofer in FULL RANGE mode or does this setting not apply to what we want for me? I ask this because the manual of my Teufel sets says:

THX SWITCH:
Full Range: THX setting for all surround modes (in this mode the crossover frequency knob and phase knob are de-activated)
Variable Frequency Control: Use this only when running the subwoofer in conjunction with a conventional stereo amplifier

See page 7 of the manual of my subwoofer which can be found here:
http://www.teufelaudio.nl/media/oart_0/oart_t/oart_35/oart_34/1723_ml_theater8_u_10_v11_eng_web.pdf


----------



## EarlK

Those "instructions" from the manual are anything but clear ( about how things actually work ) .

They seem to imply ( via using the "advanced" option ) that you can apply separate/individual crossover frequencies under specific circumstances .

Since you know how to check for the effects ( of these sort of changes ) just try it out ( as best as you can ) and measure the results .

Alternately, do what I previously mentioned ( effectively , apply 2 crossover points to your sub / a 150hz point then an 80 hz point derived in the sub itself ) .

:sn:


----------



## THX-UltraII

Good to see you are on the community everyday Earl. This way I can work much faster and do testings everynight :T



> Alternately, do what I previously mentioned ( effectively , apply 2 crossover points to your sub / a 150hz point then an 80 hz point derived in the sub itself )


But like I said, the manual of my Teufel subwoofer says:

_THX SWITCH:
Full Range: THX setting for all surround modes (in this mode the crossover frequency knob and phase knob are de-activated)
Variable Frequency Control: Use this only when running the subwoofer in conjunction with a conventional stereo amplifier_

See here page 7 http://www.teufelaudio.nl/media/oart...11_eng_web.pdf

You say to put the switch on 'VARIABLE FREQUENCY CONTROL' correct? But the manual says that one should only use this when running the subwoofer in conjunction with a conventional stereo amplifier. So I m stuck with the 'FULL RANGE' setting which means that the frequency control knob and phase knob are not active.


----------



## THX-UltraII

> Those "instructions" from the manual are anything but clear ( about how things actually work ) .
> 
> They seem to imply ( via using the "advanced" option ) that you can apply separate/individual crossover frequencies under specific circumstances


checked the Marantz community and it seems you can apply sepate Xovers for you main/center and rears but this is not what I m looking for so not usable.


----------



## EarlK

THX said:


> THX SWITCH:
> Full Range: THX setting for all surround modes (in this mode the crossover frequency knob and phase knob are de-activated)
> Variable Frequency Control: *Use this only when running the subwoofer in conjunction with a conventional stereo amplifier*
> 
> See here page 7 http://www.teufelaudio.nl/media/oart...11_eng_web.pdf
> 
> You say to put the switch on 'VARIABLE FREQUENCY CONTROL' correct? But* the manual says* that one should only use this when running the subwoofer in conjunction with a conventional stereo amplifier. *So I m stuck with the 'FULL RANGE' setting* which means that the frequency control knob and phase knob are not active.


Really ?

Really ?

WOW !!!

So you're willing to accept those written words as dogmatic directive ( ie; rules not to be broken under any circumstances ) rather than helpful guidelines ( to be interpreted at your discretion ) ? 

Amazing that .


:sn:


----------



## THX-UltraII

Check out one of my measurements from a week ago here:
http://www.hometheatershack.com/forums/rew-forum/59784-first-measurement-3.html#post534399

You would say GRAPH 1 is with all same settings exept subwoofer switch which is on FULL RANGE. Graph 4 is with all same settings exept subwoofer switch which is on VARIABLE FREQUNCY CONTROL (with var.freq.control knob on it s max setting 240).

Why is it that it gives 2 totally different results then......?


----------



## aackthpt

THX-UltraII said:


> So I m stuck with the 'FULL RANGE' setting which means that the frequency control knob and phase knob are not active.


LOL, going sarcastic, eh Earl? LOL. I can understand the sentiment.

THX, before we did this all you were pretty hard set on having the setting NOT on full range, despite that that is the manufacturer's recommended setup (which is why I suggested it as a starting point). The point is that we should be open to anything that might improve things.

At this point we are definitely into the region where I have little experience. But being that this is a bit of an unusual setup, I suspect we are getting out of anyone else's direct experience. This is where, to some extent, you have to start applying lessons Earl and I have been trying to teach you! Just as much of the figuring out how to make this work from now will be you as us--we aren't there listening to and interacting with the system.

This page may help you. Being that Denon and Marantz are pretty much the same company, you may find clearer descriptions of what things do there. If not you can post in the AVR area to see if anyone fully understands how the LF steering logic works.

I think you might have a shot at doing what Earl suggested by setting all speakers to "small", sub with 'full range' off, verifying phase, then tweaking the knob on the sub while running the RTA (with both the one main and the sub playing). The object is to combine the low-pass filter at 150Hz from the AVR with some low-pass filter in the sub to approximate the 80Hz crossover response. One of the difficulties here is that since the sub doesn't have a pre-out you can measure, you will have to do this with a final test result, though I bet that is fine since Earl used a final test result to decide this would be a good setup anyway.

You might be able to do this better with some strategically chosen filters in your feedback destroyer while keeping the subwoofer in "full range". In that case, you _can_ use its signal out to verify the final characteristic which is definitely an advantage. The limited type and number of filters in the BFD you have might limit this, or make you less able to deal with modes later--but that is just something you will have to deal with.

Thinking for the future here... my understanding is that with the ASIO drivers you can use HDMI out and ASIO4ALL to steer the signals to the surrounds. Once your main channels are working better you might want to steer the signal to the center and each surround to verify they are working well also. This is something I have not tried to do yet so I can't speak to it beyond theoretically, unfortunately. It looks like bass management doesn't work on most receivers with 7.1ch direct analog inputs, so you can't just hook up the interface to it, it appears. Also I'm not sure how much it matters as I wouldn't think much bass would be mixed into the surrounds, but they are specified for full range so I dunno. *shrug*


----------



## aackthpt

THX-UltraII said:


> You would say GRAPH 1 is with all same settings exept subwoofer switch which is on FULL RANGE. Graph 4 is with all same settings exept subwoofer switch which is on VARIABLE FREQUNCY CONTROL (with var.freq.control knob on it s max setting 240).
> 
> Why is it that it gives 2 totally different results then......?


That... does not make sense, I agree. However they aren't "totally different" results either. Most of the major features of the FR are the same. And we've had plenty of issues here with bad cal files, etc. So I would ask firstly did you definitely do everything exactly the same. Secondly were there any noise sources (HVAC for example) that may have been on during one and not the other. Thirdly what phase was the subwoofer on (and how do we know it was not shifted anyway)? Fourth, a single sweep can sometimes come out different from typical, so if a measurement is critical or you are close to finalizing a setup it helps to run the sweep more than once to verify that the results are repeatable.

If this were easy, then everyone would be doing it!


----------



## THX-UltraII

ok, check out this new measurement. both sub and main right is running. Difference is subwoofer settings (on subwoofer itself) which would result in the same outcome but it s not...... So i STILL don t know what my subwoofer does when switching the var.freq.switch......


----------



## aackthpt

THX-UltraII said:


> ok, check out this new measurement. both sub and main right is running. Difference is subwoofer settings (on subwoofer itself) which would result in the same outcome but it s not...... So i STILL don t know what my subwoofer does when switching the var.freq.switch......


The problem with putting the sub on "0" is that we don't really know if that is 0 or if there is a phase shift in the electronics in the sub, therefore IMO you need to re-set up the phase with the "full range" switch off. Since that big dip in the response at ~65/78 Hz is pretty well "in the pocket" of the crossover range, it could be the nulling that I mentioned using the "inverse method". Maybe take a sweep with the sub phase set at 180 and see if it goes away; if it does then you should most definitely re-set up the phase with the "full range" off. It should be quite simple to figure out using the RTA and noise generator also, though.


----------



## THX-UltraII

aackthpt said:


> The problem with putting the sub on "0" is that we don't really know if that is 0 or if there is a pha se shift in the electronics in the sub, therefore IMO you need to re-set up the phase with the "full range" switch off. Since that big dip in the response at ~65/78 Hz is pretty well "in the pocket" of the crossover range, it could be the nulling that I mentioned using the "inverse method". Maybe take a sweep with the sub phase set at 180 and see if it goes away; if it does then you should most definitely re-set up the phase with the "full range" off. It should be quite simple to figure out using the RTA and noise generator also, though.


Already did this for this measurements. The phase is 100% correct in both measurements..... 

Earl?


----------



## THX-UltraII

and here is the same measurement as the one in post #123 but with two extra measurements from the subwoofer only (Graph 3 and Graph 4).
Now I really don t understand the difference in Graph 1 and 2 anymore when looking at Graph 3 and Graph 4 (which are identical up to 80Hz!!!)

EDIT: forgot to attach the .mdat file. Will do this in 6 hours when I m home.


----------



## EarlK

As of now, I'm on an indefinite break ( from participating in this thread ) .

:sn:


----------



## THX-UltraII

EarlK said:


> As of now, I'm on an indefinite break ( from participating in this thread ) .
> 
> :sn:


I m doing the the best I can to understand en learn Earl 

The .mdat is too big so here are the 4 measurements:

*Graph 1:*
MAIN RIGHT+SUB PLAYING
AVR CO80
SUBWOOFER SETTINGS
switch on full range
so phase control knob and var.freq. control kob not active)

*Graph 2:*
MAIN RIGHT+SUB PLAYING
AVR CO80
SUBWOOFER SETTINGS:
switch on var. freq. control
var. freq. control knob on max (240)
phase control knob on 80%(which is correct phase)

*Graph 3:*
SUB ONLY PLAYING
SUBWOOFER SETTINGS
switch on full range
so phase control knob and var.freq. control kob not active)

*Graph 4:*
SUB ONLY PLAYING
SUBWOOFER SETTINGS:
switch on var. freq. control
var. freq. control knob on max (240)
phase control knob on 80%(which is correct phase)

*picture 5:*
All 4 Graph s combined


----------



## jtalden

Sander,

I am not sure what you are asking here but...

If you just want to confirm that the XO and SW settings are set up in a conventional manor, then I can give you my opinion on that. If you are still just trying to understand all the ins-and-outs of the effect all the various controls there are there are then that is best done via your own experimentation. It is possible to get to about the same SPL response in several different ways so it is not possible to say there is one best solution. I do think there is one conventional setup using a modern AVR. The conventional method is to allow the AVR to control all XO functions. The SW needs no controls. In your case I take it that it that the SW can be set to Full Range to allow the AVR to do its job.

If you decide you want my input on this, then provide an .mdat containing 3 measurements; SW, FR, SW+FR. Please turn on the loopback feature (if you know how), if not, I can probably still use the data, but it is a little more difficult for me. The conditions should be the same as in your Graph 1 above (Full range, CO80). 

[I expect to be able show that with the correct distance setting the results will be very similar to the results you achieved in your Graph 2. You are just having the SW controls compensate for a distance setting issue in the AVR. That is my theory at this point anyway.]

If I don’t understand what you are trying to accomplish/understand or you are not interested is getting my input then please just ignore this.


----------



## THX-UltraII

jtalden said:


> Sander,
> 
> I am not sure what you are asking here but...
> 
> If you just want to confirm that the XO and SW settings are set up in a conventional manor, then I can give you my opinion on that. If you are still just trying to understand all the ins-and-outs of the effect all the various controls there are there are then that is best done via your own experimentation. It is possible to get to about the same SPL response in several different ways so it is not possible to say there is one best solution. I do think there is one conventional setup using a modern AVR. The conventional method is to allow the AVR to control all XO functions. The SW needs no controls. In your case I take it that it that the SW can be set to Full Range to allow the AVR to do its job.
> 
> If you decide you want my input on this, then provide an .mdat containing 3 measurements; SW, FR, SW+FR. Please turn on the loopback feature (if you know how), if not, I can probably still use the data, but it is a little more difficult for me. The conditions should be the same as in your Graph 1 above (Full range, CO80).
> 
> [I expect to be able show that with the correct distance setting the results will be very similar to the results you achieved in your Graph 2. You are just having the SW controls compensate for a distance setting issue in the AVR. That is my theory at this point anyway.]
> 
> If I don’t understand what you are trying to accomplish/understand or you are not interested is getting my input then please just ignore this.


Thanks for your reply. Let me try to explain again what I mean:


When you look at Graph 3 and 4 (subwoofer only measurements) they look the same untill approx 100Hz. This makes sense to me because:
with Graph 4 my subwoofer switch is set on VARIABLE FREQUNCY CONTROL and the VARIABLE FREQ.CONTROL KNOB is set on it s maximum which is 240Hz. That is why the freq.response from 100-400Hz is lower than the freq. response in this area in Graph 3 (which is the FULL RANGE switch setting of my subwoofer).

What I DON T understand is the difference in Graph 1 and Graph 2:
The dips at 65 and 75Hz in Graph 1 are much deeper than the ones in Graph 2. Graph 1 is the one where the MAIN channel is combined with the setting subwoofer switch on FULL RANGE (Graph 3) and Graph 2 is the one where the MAIN channel is combined with the subwoofer switch on VARIABLE FREQ. CONTROL (Graph 4).

The difference COULD be explained by the phase that is different but I m 100% sure that it IS NOT. I ve checked that the phase was correct (and the same) with BOTH combinations. With setting FULL RANGE on my subwoofer (Graph 3) the PHASE is NOT ACTIVE on my subwoofer so I found the correct phase setting by playing with the distance setting in my AVR only. With setting VIARIABLE FREQ.CONTROL on my subwoofer (Graph 4) the PHASE KNOB on my subwoofer is activated. So what I did is leaving the distance setting on my AVR as it was with the FULL RANGE setting of my subwoofer and adjust the phase knob on my subwoofer to find the correct phase.
So with both on the correct phase WHY can it be that there is such a big difference in Graph 1 and 2?


You also might be wondering what method I m using to determine the right phase:
What I do is play a 80Hz tone that is played by both my subwoofer and main channel. I place my SPL meter on a horizontal position at listening position at ear height and look for a volume so that the subwoofer and main channel play at approx. the same level. Next thing I do is adjust the phase (with setting of my subwoofer on FULL RANGE only with the distance setting of my AVR and with the setting of my subwoofer on VAR.FREQ.CONTROL with the phase knob of my subwoofer) untill I find the HIGHEST value on my dB meter.



Hope you understand better now what I am asking which is in short:
WHY is there a difference in Graph 1 and Graph 2 while you would say this cannot be?


----------



## Barleywater

All your measurements set impulse peak at t=0. This is straight up wrong! Especially when working with crossovers. Please set Preferences, Analysis, “Use Loopback as Timing Reference”. Use one channel of sound card for measurement, and use other channel for timing reference. Here is wave superposition at work: When using AVR as crossover, set sub to full range, measure sub alone, main alone, and sub + main. Don’t change levels, don’t move microphone. Sit in exact same spot. In REW, “All SPL” window open controls to do “Trace Arithmetic” A + B for sub alone with main alone. It should be virtually identical to measurement of “sub + main”. Generate trace of “sub alone – main alone” and it should be identical to running measurement with leads to mains terminals reversed.

Instead of trying to use subwoofer crossover and phase knob (inactive in full range mode anyway), use AVR channel delays to modify the way sub and main add up at listening position. With time referenced IR of sub and main responses you can investigate and predict effects of delay settings in REW. You can move t=0 relative to impulse responses in “Impulse” window, and then check out predicted performance with trace arithmetic, and confirm by setting delays in AVR. Applying offsets in “SPL &Phase” adjusts relative levels, and are reflected in trace arithmetic too. Lots less hunting, fishing by tweaking, measuring and do it again and again. Science. . Target is flat for sum, and deepest notch for difference.

I’ve attached mdat of Linkwitz-Riley 24db/octave 80Hz crossover measurements using DCX2496 as demo of loopback timing v peaks at t=0 showing trace arithmetic in action. You should play around with peak timings and trace arithmetic to become familiar.

In summary post #11 is perfect assessment. Make changes, experience changes. 

AVR manufacture has a plan. The Butterworth HP filters of AVR anticipate roll in mains. Measure full range response of mains, and smooth generously to find corner of low frequency roll off. Start by setting crossover in that range. EQ for flatness. Check notch formed by reversing mains leads, or in REW trace arithmetic. Tweak delays to improve flatness of sum and depth of notch with difference.

Play with it! Enjoy.


----------



## THX-UltraII

> In REW, “All SPL” window open controls to do “Trace Arithmetic” A + B for sub alone with main alone. It should be virtually identical to measurement of “sub + main”. Generate trace of “sub alone – main alone” and it should be identical to running measurement with leads to mains terminals reversed.


Sorry, but I don t understand any of this . The problem is that English is not my native language and on top of that I m a REW noob. Are you saying that my measurements are not done right? I ve exactly followed the REW help file to set up everything properly. Are you saying that all my measurements are not ok and I have to measure always with the setting “Use Loopback as Timing Reference” checked?



> You can move t=0 relative to impulse responses in “Impulse” window, and then check out predicted performance with trace arithmetic, and confirm by setting delays in AVR. Applying offsets in “SPL &Phase” adjusts relative levels, and are reflected in trace arithmetic too.


Can you explain this again maybe but then in a not so technical way?


----------



## jtalden

THX-UltraII said:


> Thanks for your reply. Let me try to explain again what I mean:
> 
> 
> When you look at Graph 3 and 4 (subwoofer only measurements) they look the same untill approx 100Hz. This makes sense to me because:
> with Graph 4 my subwoofer switch is set on VARIABLE FREQUNCY CONTROL and the VARIABLE FREQ.CONTROL KNOB is set on it s maximum which is 240Hz. That is why the freq.response from 100-400Hz is lower than the freq. response in this area in Graph 3 (which is the FULL RANGE switch setting of my subwoofer).
> 
> What I DON T understand is the difference in Graph 1 and Graph 2:
> The dips at 65 and 75Hz in Graph 1 are much deeper than the ones in Graph 2. Graph 1 is the one where the MAIN channel is combined with the setting subwoofer switch on FULL RANGE (Graph 3) and Graph 2 is the one where the MAIN channel is combined with the subwoofer switch on VARIABLE FREQ. CONTROL (Graph 4).
> 
> The difference COULD be explained by the phase that is different but I m 100% sure that it IS NOT. I ve checked that the phase was correct (and the same) with BOTH combinations. With setting FULL RANGE on my subwoofer (Graph 3) the PHASE is NOT ACTIVE on my subwoofer so I found the correct phase setting by playing with the distance setting in my AVR only. With setting VIARIABLE FREQ.CONTROL on my subwoofer (Graph 4) the PHASE KNOB on my subwoofer is activated. So what I did is leaving the distance setting on my AVR as it was with the FULL RANGE setting of my subwoofer and adjust the phase knob on my subwoofer to find the correct phase.
> So with both on the correct phase WHY can it be that there is such a big difference in Graph 1 and 2?
> 
> 
> You also might be wondering what method I m using to determine the right phase:
> What I do is play a 80Hz tone that is played by both my subwoofer and main channel. I place my SPL meter on a horizontal position at listening position at ear height and look for a volume so that the subwoofer and main channel play at approx. the same level. Next thing I do is adjust the phase (with setting of my subwoofer on FULL RANGE only with the distance setting of my AVR and with the setting of my subwoofer on VAR.FREQ.CONTROL with the phase knob of my subwoofer) untill I find the HIGHEST value on my dB meter.
> 
> 
> 
> Hope you understand better now what I am asking which is in short:
> WHY is there a difference in Graph 1 and Graph 2 while you would say this cannot be?


Yes, I understood your concern reasonably well.

I theorized:
> The difference in the 2 methods is because the distance setting in the AVR is very likely incorrect.
> When SW variable phase is turned on and set to 240 the SW is compensating for the distance setting error in the AVR. 
> Given the 3 measurements I requested above I offered to demonstrate that issue and explain it. 
> The outcome would be expected to be a new setting of the AVR distance. With that setting the same SPL curve would be achieved either, using SW to variable and 0 phase or, with the SW set to full range. That SPL curve would be the same SPL curve now being achieved with the SW variable phase and a setting of 240.


----------



## THX-UltraII

thxz for your reply jtalden.

I thought/think my phase (distance) setting in my AVR with the subwoofer on FULL RANGE was ok but apparantly it is not (as you are saying).

I will make the 3 measurements as you requested:
SW, FR, SW+FR with the loopback feature turned on and all the conditions the same as in Graph 1 I posted earlier. (Full range, CO80).

About the loopback feature, is it correct that I have to do this:
1. I go to Preferences, Analysis and check the box 'Use Loopback as Timing Reference'. I don t understand what the manual exactly says about the 'Sub-sample Timing Adjustment' and 'Decimate IR' options. *Do I check these boxes or not??*
2. Connect the LEFT output of the Tascam the LEFT input on the front side of my Tascam (with a RCA cable with 1/4'' jack plugs)
3. Set the INPUT LEVEL LEFT knob of my Tascam to the exact same value (85% in my case) as the INPUT LEVEL RIGHT knob of the Tascam.
4. Do the 3 measurements you requested.


----------



## jtalden

THX-UltraII said:


> thxz for your reply jtalden.
> 
> I thought/think my phase (distance) setting in my AVR with the subwoofer on FULL RANGE was ok but apparantly it is not (as you are saying).
> 
> I will make the 3 measurements as you requested:
> SW, FR, SW+FR with the loopback feature turned on and all the conditions the same as in Graph 1 I posted earlier. (Full range, CO80).
> 
> About the loopback feature, is it correct that I have to do this:
> 
> 
> 
> 1. I go to Preferences, Analysis and check the box 'Use Loopback as Timing Reference'. I don t understand what the manual exactly says about the 'Sub-sample Timing Adjustment' and 'Decimate IR' options. *Do I check these boxes or not??*
> 
> 
> 
> Check all three boxes.
> 
> 
> 
> 
> 2. Connect the LEFT output of the Tascam the LEFT input on the front side of my Tascam (with a RCA cable with 1/4'' jack plugs)
> 
> Click to expand...
> 
> Yes.
> 
> 
> 
> 
> 3. Set the INPUT LEVEL LEFT knob of my Tascam to the exact same value (85% in my case) as the INPUT LEVEL RIGHT knob of the Tascam.
> 
> Click to expand...
> 
> The level of the loopback is not critical anything between 50% and 99% will work the same. 85% is a good setting.
> 
> 4. Do the 3 measurements you requested.
Click to expand...

Yes, keep all other conditions the same for all measurements. 

OH, it just occured to me that it is best that you also measure SW+FR the with "Variable/240" setup (just like Graph 2) because that way I can easily overlay the results of my adjustment to that result too see if it is then similar. So now I am requesting 4 measurements - sorry. If all 4 are taken with same setup that will avoid comparisons of SPL curves tham may vary due to mic position or other setup differences.


----------



## THX-UltraII

Thxz! will do the requested measurements in two cours from now. Hope you ll still be around by then


----------



## THX-UltraII

Hope these are the measurements you where asking me. I added 2 more measurements besides the 4 you asked for: SUB ONLY with var.freq.control on subwoofer and MAIN RIGHT only with var.freq.control on subwoofer.

Here is the link where I uploaded the file (to big to post on the forum):

http://www.filefactory.com/file/5mw0g1u5ti99/n/jtalden_mdat


----------



## jtalden

I just looked at the file.
The IR Loopback timing did not come through for some reason. Either the loopback was not setup correctly or possibly you pushed the buttons on each measurement to "estimate IR delay" and then "shift IR" before you saved the file and posted it for me? 

I will try to use this data anyway, but it will be tricky to determine your original IR timing.

It is also interesting that the FR speaker IR measurement is significantly different depending on the setting on the SW. I am not sure why that should be. Are you running speaker wires from the AVR directly to the FL and FR speakers? Are you running a line level (RCA or XLR) from the AVR SW-output to the SW?


----------



## THX-UltraII

> I just looked at the file.
> The IR Loopback timing did not come through for some reason. Either the loopback was not setup correctly or possibly you pushed the buttons on each measurement to "estimate IR delay" and then "shift IR" before you saved the file and posted it for me?


I didnt do anything. I checked the correct boxes in the preferences, put a rca cable from the left output to the left input of the tascam and did the measurement as usual.


> It is also interesting that the FR speaker IR measurement is significantly different depending on the setting on the SW. I am not sure why that should be. Are you running speaker wires from the AVR directly to the FL and FR speakers? Are you running a line level (RCA or XLR) from the AVR SW -output to the SW?


? the front speaker measurement is the same with both subwoofer settings isn t it?? speaker wires are running directly from amplifier (I use my avr as processor and have a separate 5 channel amplifier which is connected unbalanced/rca to the pre-outs of my processor/avr). Subwoofer is connected to the regular (mono) subwoofer pre-out of my avr (with Behringer eq between it which is in 'BYPASS' mode for the moment/untill I m going to do the final subwoofer eq)

Attached pic with mains only running with sub in FULL RANGE and VAR.FREQ.CONTROL


----------



## jtalden

Sander,
In all charts below the first 6 measurements are your original ones. Note that I rename them for these charts. The remaining 8 traces are my calculations obtained by shifting the relative IR timing of the FR vs. the SW. This is the same as actually changing the speaker distance in the AVR and remeasuring. I will refer to all the measurement or calculations by their REW memory position (m1 to m14) for convenience.

Since the original IR timing info was lost for some reason, I estimated it by finding timing that resulted in the same SPL response that you measured (your measured m3 Vs my calculated m10). 
Fig1:








I then changed the IR timing in 2 ms increments from that point to find an SPL trace that is similar to your result in m6 “SW+FR v160”. I found this at 3 different timings, either increasing the FR distance by 10 ms (m12) or decreasing FR distance by -8ms (m11), or alternatively, Inverting the polarity of the SW and increasing the FR distance 1 ms (m14) 
Fig2:








These are indeed the best timing alignments that is possible for this setup. All other settings look worse. The setup you found with the m6 (SW+FR v160) just as good as the ones I found.

I would prefer the m12, or the m14 setup as there is less group delay. I don’t m11 as much because the SW IR is lagging the FR IR by too much in my opinion. Below is the IR timing for the original and each of the 3 solutions. Maybe you can see what I mean. 

Fig3a: (Original Timing) 








Fig3b: (M11 timing)








Fig3c (M12 timing)






:

Fig3d: (M14 timing)








The m14 setting is the more conventional one. This is normally what I find when I tested the Audyssey automated alignments (when it works correctly).

The phase responses showed them all to be equally good (Figures not shown). 

Major conclusions:
> Distance settings changes found in this experiment:
- m11 decreases the FR distance 3.44 m
- m12 increases the FR distance 2.75 m
- m14 decreases the FR distance 0.34 m (SW polarity must also be changed)

> SPL response can be optimized in 2 or 3 (or more) IR timings (speaker distances). Each will provide very similar SPL results. If you want to choose among them I suggest you listen to them. I do find they sound different, but each has its pros and cons.
> It is common to set the initial rise of the 2 IRs as the initial starting point and then adjust in 1 or 2 ms increments until a maximum SPL level is achieved in the XO range.
> The alignment can be done either on line by actually changing the distance in the AVR and measuring again, or off line by calculation as done here.
> 2 ms is about 0.69 m and that is okay resolution for SW distance settings. I did not show all the curves I generated, but changes less than 2 m do not have a large impact. You can fine tune as small as your AVR allows. It just takes a longer for little improvement.

Notes:
> The distance settings in you AVR may limit the timing that can be set. 

> There is no issue with changing the polarity on the SW (it is now Positive polarity).

Calculating method use here:
> The SW IR was copied and then shifted by the number of ms indicated. The FR measurement was left unchanged for the calculations. 
[When actually changing the setup however the FR distance/timing must be changed as any change to the SW will impact all main speaker timings. It is the relative distance difference that is important not the absolute numbers.]

> To shift the SW IR and calculate the response of a new alignment:
- First copy the reference SW measurement using the control panel on the “All SPL” tab. That is done by selecting the SW measurement in trace arithmetic in both “A:” and “B:” boxes. Then select the “(A + B)/2” as the formula and then select “Generate”. That just creates an exact copy.
- Then shift that new SW IR (in the IR tab control box) by the number of ms you choose. I then rename it to keep track.
- Then back to the All SPL trace arithmetic control box. There you select the FR measurement for A: and the new shifted SW trace for B:
- Then select the “A + B” formula and select “calculate”. You now have the same response you would get if you actually shifted the AVR distance by that amount.

> It would have been better to have the original IR timing for sure, but if my guess as to the initial timing is off by one wavelength it is not critical. It is the relative shift that is important, so the change in relative distance is still the same. The impact would be that the timing of the results may actually be m11 instead of m12 for instance.

I hope this is helpful Sander for your understanding and if not for you then hopefully for someone else. It is just one method confirming the SW to Main speaker distance/timing is correct. Adjusting the distance it with the RTA probably works fine. I would still want to measure the SW, Main, SW+Main for each speaker to confirm the IR locations are reasonable.


----------



## jtalden

THX-UltraII said:


> I didnt do anything. I checked the correct boxes in the preferences, put a rca cable from the left output to the left input of the tascam and did the measurement as usual.
> ? the front speaker measurement is the same with both subwoofer settings isn t it?? speaker wires are running directly from amplifier (I use my avr as processor and have a separate 5 channel amplifier which is connected unbalanced/rca to the pre-outs of my processor/avr). Subwoofer is connected to the regular (mono) subwoofer pre-out of my avr (with Behringer eq between it which is in 'BYPASS' mode for the moment/untill I m going to do the final subwoofer eq)


> The wiring is fine.
> The SPL charts are the same but I noticed what appeared to be a difference in the IR chart that suggested a little more phase rotation on one of them. It is not important, as it was minor and would not cause an issue. It just raised the wiring question in my mind.
> It did the analysis okay without the loopback timing as I posted. I'm pretty confident I found a pretty close match to your timing through trial and error.

Let me know your results if you actually measure with one or more of the settings I found.


----------



## Barleywater

John,

Nice work up.

Sander,

Hopefully settings will bring improvement. John and I use same approach to finding solutions for these situations. You have to work and play with the underlying physics though if you want to learn how to do this. May John's work be good example.

I've looked at spectrograms of your full range measurements and it's not very pretty. Lots of ripple extending well beyond SW range. I feel you will get much more out of your BFD if it is placed in processing loop so that it works on both subwoofer and full range speakers. But I don't know if this is possible with your AVR.

Andrew


----------



## THX-UltraII

Morning guys and ecspecially thanks to you John, for giving such good information and help!

I ve read your post more then 10 times now  and everytime I read it things get clearer to me. I still have some things I don t understand. Let me try to say some things about your post in my own words to see if I understand it a little:

Because you did not get the original IR timing from me you looked for a timing that resulted in the same curve as my measurement 3 (SUB+FRONT BOTH PLAYING and subwoofer in FULL RANGE MODE). Despite the fact I ve read your post many times now I cannot find out HOW you actually found this timing that looked the same like my measurement 3 (maybe you can explain this step-by-step how that you did this?).

After above procedure you made changes in the IR timing by 2ms and everytime you made a 2ms change you looked at the outcome curve. After a lot of these '2ms-changes' you picked 8 'estimated' measurements and from these 8 measurements there are 3 measurements that gave the flatest curve with the least peaks and dips (which looks almost the same as my measurements 6 which assumes I had done the phase tuning correct?). You say you did this by shifting the *relative IR timing* of the Front Right vs. the Subwoofer which is the same as changing distances in the AVR and measure again after these distance changes. At the bottom of your post #140 you describe in detail how to do this shifting. (I ll come back later on this in this reply).



From that point it even got harder (group delay) for me to understand but here we go:

Am I correct that now you had found the best 3 curves the next thing you did is go look at the group delay times and see if they are correct? (I still don t know what group deplay actually is). You ask my in your post if I see what you mean with the timing charts you posted but I don t understand how to read them. Vertical is the %FS and horizontal the time in ms but how to read this/understand what happens in the charts is not clear to me. Of course I do see differences in the charts but that s it......


Next are your major conclusions:
_> Distance settings changes found in this experiment:
- m11 decreases the FR distance 3.44 m
- m12 increases the FR distance 2.75 m
- m14 decreases the FR distance 0.34 m (SW polarity must also be changed)_
I think (and again correct me if I m wrong) that m12 is my only option because I cannot change the polarity of my subwoofer (polarity switching is go from 0->180degree with phase knob correct? If so, I cannot change the phase when running my subwoofer in Full Range mode).

Other conclusions from you:
_> SPL response can be optimized in 2 or 3 (or more) IR timings (speaker distances). Each will provide very similar SPL results. If you want to choose among them I suggest you listen to them. I do find they sound different, but each has its pros and cons._
Understand!

_> It is common to set the initial rise of the 2 IRs as the initial starting point and then adjust in 1 or 2 ms increments until a maximum SPL level is achieved in the XO range._
With this you mean to start with the original measurement and from that piont start increasing (or decreasing) in 1-2ms until the best curve is reached?

_> The alignment can be done either on line by actually changing the distance in the AVR and measuring again, or off line by calculation as done here._
Understand!

_> 2 ms is about 0.69 m and that is okay resolution for SW distance settings. I did not show all the curves I generated, but changes less than 2 m do not have a large impact. You can fine tune as small as your AVR allows. It just takes a longer for little improvement._
Is it always 0.69m for everyone with every measurement?


Your notes:
_> The distance settings in you AVR may limit the timing that can be set._
My AVR has 0.01m increments for distance settings so thats good.

_> There is no issue with changing the polarity on the SW (it is now Positive polarity)._
Like I said I cannot change the polarity of the subwoofer in Full Range can I?

_> The SW IR was copied and then shifted by the number of ms indicated. The FR measurement was left unchanged for the calculations. 
[When actually changing the setup however the FR distance/timing must be changed as any change to the SW will impact all main speaker timings. It is the relative distance difference that is important not the absolute numbers.]_This is an important one isn t it? Let see if I understand it:
You ALWAYS copy and shift the subwoofer measurement and not the main right measurement (with the result of changing the main right distance) because if you copy and shift the main right measurement then you have to make changes to the subwoofer distance and other channel measurements will not be correct anymore when you constantly switch the subwoofer distance. Am I correct that I can make out of this information that I can (have?) to do this difficult and extensive procedure for all (main right, main left, center, surround right and surround left) my channels?
One more thing about this note. You say that _it is the relative distance difference that is important and not the absolute numbers_. I don t understand what you mean with this.

_> To shift the SW IR and calculate the response of a new alignment:_
This is for later or else it gets too much. I first have to understand everything that you did before I start doing it myself.

_> It would have been better to have the original IR timing for sure, but if my guess as to the initial timing is off by one wavelength it is not critical. It is the relative shift that is important, so the change in relative distance is still the same. The impact would be that the timing of the results may actually be m11 instead of m12 for instance._
Don t know why you didn t get the original IR timing (still struggling with this term and what is actually is, sorry m8 ) but I think I did everything (checkbox and loopcable) that is needed for it......

_I hope this is helpful Sander for your understanding and if not for you then hopefully for someone else. It is just one method confirming the SW to Main speaker distance/timing is correct. Adjusting the distance it with the RTA probably works fine. I would still want to measure the SW, Main, SW+Main for each speaker to confirm the IR locations are reasonable._
This is just awesome what you did (take time for it and try to explain everything (there are still bits for me to figure out but that will come with a new answers from you I hope).

A lot of (for me) unanswered questions in this extensive reply so I hope you can answer some of them so the puzzle fits better for me.

ps. Sorry for my bad English but it is not my native language


----------



## THX-UltraII

jtalden said:


> >It just raised the wiring question in my mind.


I don t have a clue either.


----------



## THX-UltraII

Barleywater said:


> John,
> 
> Nice work up.
> 
> Sander,
> 
> Hopefully settings will bring improvement. John and I use same approach to finding solutions for these situations. You have to work and play with the underlying physics though if you want to learn how to do this. May John's work be good example.
> 
> I've looked at spectrograms of your full range measurements and it's not very pretty. Lots of ripple extending well beyond SW range. I feel you will get much more out of your BFD if it is placed in processing loop so that it works on both subwoofer and full range speakers. But I don't know if this is possible with your AVR.
> 
> Andrew


Very nice of John indeed! Really appreciate it.

What are spectrograms and what do they tell? The BFD is not so good to use with the main speakers because of it s noise. I have a high-end amplifier (NuForce MCH-2-C5) and don t want to put a DA/AD converter between it. Maybe I can see if I do can achieve some good resultst by EQ the subwoofer with the Behringer and EQ the mains a little with the Marantz SR5005 own EQ?

But first things first and that is set up everything properly as for settings in processor. This is a learning curve where John is helping greatly until now!


----------



## aackthpt

THX-UltraII said:


> _> 2 ms is about 0.69 m and that is okay resolution for SW distance settings. I did not show all the curves I generated, but changes less than 2 m do not have a large impact. You can fine tune as small as your AVR allows. It just takes a longer for little improvement._
> Is it always 0.69m for everyone with every measurement?


The speed of sound in air is nearly constant. Therefore the distance sound travels in a given time is also constant. You can find a calculator to easily go between time and distance for sound right here.



> One more thing about this note. You say that _it is the relative distance difference that is important and not the absolute numbers_. I don t understand what you mean with this.


Let's say you had your mains, center, surrounds equal distance from you and they are all set at 3m, and the subwoofer is set at 4.5m. Well, if you set the array at 1m and the sub at 2.5m you will achieve the same result. Same if you set the array 6m and the sub 7.5m. Because the distance and time are directly related, and what you are really trying to achieve is time alignment.

I think it's possible you might have some level of msimatch between the video and the audio in such a scenario, but we have been ignoring that and simply trying to get the audio right.

*jtalden*, would you say that the method you did here is better, or would it be preferable to use the small-bandwidth sweep that you showed in the other thread? That seemed more self-explanatory to me. The fact that you could bring the waveforms into direct alignment seemed much clearer to me.


----------



## jtalden

THX-UltraII said:


> Morning guys and ecspecially thanks to you John, for giving such good information and help!
> 
> I ve read your post more then 10 times now  and everytime I read it things get clearer to me. I still have some things I don t understand. Let me try to say some things about your post in my own words to see if I understand it a little:


These are all good questions and I will see if I can help with some of them.



> Because you did not get the original IR timing from me you looked for a timing that resulted in the same curve as my measurement 3 (SUB+FRONT BOTH PLAYING and subwoofer in FULL RANGE MODE). Despite the fact I ve read your post many times now I cannot find out HOW you actually found this timing that looked the same like my measurement 3 (maybe you can explain this step-by-step how that you did this?).


I started with the initial rise of the 2 IRs aligned (SW and FR). That alignment did not produce the SPL you measured so I then shifted the SW IR and looked at the impact to the SPL. When I found an offset that matched your measured SPL with minimum shifting that is the alignment I assumed you are currently set up at. It may be in error by 1 wavelength, but probably not. This process was a workaround and not recommended. It is far better to get the REW loopback feature working properly so the real IR alignment is known. The step by step by how to make the shifts is the same as previously indicated. I did use finer increments to try to match the SPL very closely.



> After above procedure you made changes in the IR timing by 2ms and everytime you made a 2ms change you looked at the outcome curve. After a lot of these '2ms-changes' you picked 8 'estimated' measurements and from these 8 measurements there are 3 measurements that gave the flatest curve with the least peaks and dips (which looks almost the same as my measurements 6 which assumes I had done the phase tuning correct?). You say you did this by shifting the *relative IR timing* of the Front Right vs. the Subwoofer which is the same as changing distances in the AVR and measure again after these distance changes. At the bottom of your post #140 you describe in detail how to do this shifting. (I ll come back later on this in this reply).


I ran a whole series of 2 ms SW IR shifts in both directions. I then deleted all but 4 of them, the 4 that were of interest to this effort. Each of the 4 used 2 memory locations; 1 for the shifted SW and 1 for the resulting “shifted SW + FR” response. The order of the 8 responses I added are not logical as I did not go to the work necessary to reorder them. You can make out the which pairs go together by deciphering my naming method. 



> From that point it even got harder (group delay) for me to understand but here we go:
> 
> Am I correct that now you had found the best 3 curves the next thing you did is go look at the group delay times and see if they are correct? (I still don t know what group deplay actually is). You ask my in your post if I see what you mean with the timing charts you posted but I don t understand how to read them. Vertical is the %FS and horizontal the time in ms but how to read this/understand what happens in the charts is not clear to me. Of course I do see differences in the charts but that s it......


Yes, I selected the 3 solutions that provided the most improved SPL response as potential settings for your system. You can read up on IR in general (it’s a big subject), but for our purpose you can just think of the IR as showing when a pulse signal from the speaker will arrive at your LP. The large loop IR is the shifted SW IR and compact sharper one with the peak at 0 ms is the FR IR. The AVR speaker distance setting changes the delay of the signal to that speaker so it will have the same effect as I have shown here. Since the real time to the LP was lost because the loopback did not work. I set the FR to 0 ms and adjusted the SW IR as needed relative to it. We are interested in the relative timing anyway. 



> Next are your major conclusions:
> _> Distance settings changes found in this experiment:
> - m11 decreases the FR distance 3.44 m
> - m12 increases the FR distance 2.75 m
> - m14 decreases the FR distance 0.34 m (SW polarity must also be changed)_
> I think (and again correct me if I m wrong) that m12 is my only option because I cannot change the polarity of my subwoofer (polarity switching is go from 0->180degree with phase knob correct? If so, I cannot change the phase when running my subwoofer in Full Range mode).


Many SWs have a switch for convenience. There may be an adaptor to reverse the polarity, or you can make up your own RCA cable to swap the 2 wires at one end. You can also just use one of the other 2 setups that don’t require reversed polarity.



> Other conclusions from you:
> _> SPL response can be optimized in 2 or 3 (or more) IR timings (speaker distances). Each will provide very similar SPL results. If you want to choose among them I suggest you listen to them. I do find they sound different, but each has its pros and cons._
> Understand!
> 
> _> It is common to set the initial rise of the 2 IRs as the initial starting point and then adjust in 1 or 2 ms increments until a maximum SPL level is achieved in the XO range._
> With this you mean to start with the original measurement and from that piont start increasing (or decreasing) in 1-2ms until the best curve is reached?


Yes. Normally we want to maximize the output through the XO range even if we then need to EQ it back down a little to correct the room response. Your XO range is low to start with, so it is clear you want the max output there.



> _> The alignment can be done either on line by actually changing the distance in the AVR and measuring again, or off line by calculation as done here._
> Understand!
> 
> _> 2 ms is about 0.69 m and that is okay resolution for SW distance settings. I did not show all the curves I generated, but changes less than 2 m do not have a large impact. You can fine tune as small as your AVR allows. It just takes a longer for little improvement._
> Is it always 0.69m for everyone with every measurement?


I just wanted to provide some sense of the sensitivity of the alignment to changes. I just picked a convenient number that was a balance between saving time and getting an acceptably accurate answer. The same increment is not for everyone. Most will just make a FR distance change in the AVR and then remeasure and check the charts. It's much easier than doing this complicated offline calculation. 



> Your notes:
> _> The distance settings in you AVR may limit the timing that can be set._
> My AVR has 0.01m increments for distance settings so thats good.
> 
> _> There is no issue with changing the polarity on the SW (it is now Positive polarity)._
> Like I said I cannot change the polarity of the subwoofer in Full Range can I?


Addressed above.



> _> The SW IR was copied and then shifted by the number of ms indicated. The FR measurement was left unchanged for the calculations.
> [When actually changing the setup however the FR distance/timing must be changed as any change to the SW will impact all main speaker timings. It is the relative distance difference that is important not the absolute numbers.]_This is an important one isn t it? Let see if I understand it:
> You ALWAYS copy and shift the subwoofer measurement and not the main right measurement (with the result of changing the main right distance) because if you copy and shift the main right measurement then you have to make changes to the subwoofer distance and other channel measurements will not be correct anymore when you constantly switch the subwoofer distance. Am I correct that I can make out of this information that I can (have?) to do this difficult and extensive procedure for all (main right, main left, center, surround right and surround left) my channels?


No. The calculation method is silly if you are sitting with your measuring equipment in your theater. This effort was intended to be primarily a teaching exercise to help you understand what the distance setting does and what effect it has on the room measurements. In practice just change the FR distance and remeasure until the proper IR alignment is achieved as shown in the IR chart and the SPL chart. Then move to the next main speaker and do it again. The SW distance cannot be changed or you need start over as it affects all the main speakers. Just leave it at the measured distance or at the distance that the AVR automated setup routine establishes.



> One more thing about this note. You say that _it is the relative distance difference that is important and not the absolute numbers_. I don t understand what you mean with this.


If the SW is set a 2 m and you set the FR at 1.5 m per your testing then the difference is -0.5m (or 0.69 ms). The AVR will thus send the signal to the FR 0.69 ms later than the signal it sends to the SW so that they will both arrive at the LP at the timing you established for good SPL response. This is the same result that would occur is the SW was set at 5 m and the FR was set at 4.5 m. There would still be at difference of .069 ms between the signals.

That answers most of your questions. 

The process is simple to do when you do it by remeasuring and you know what to look for in the charts. 

I did not try to explain the Group Delay and Phase chart analysis as that adds additional complexity that is unnecessary for good results. Just keep the initial rise of the 2 IRs reasonably close to each other as shown with the 3 solutions here and the GD and Phase will be acceptable.


----------



## jtalden

aackthpt said:


> *jtalden*, would you say that the method you did here is better, or would it be preferable to use the small-bandwidth sweep that you showed in the other thread? That seemed more self-explanatory to me. The fact that you could bring the waveforms into direct alignment seemed much clearer to me.


Both can work. So can various other methods.

I haven't used the Narrow Bandwidth Sweep method, but once or twice. I just tested the concept on my setup to see if it would work. It did for me, but I imagine that alignment method may be confusing to some people. I also worry that some room responses may provide a confusing IR trace due to room modes? 

I have more confidence in the SPL/IR method described above. Also, it is necessary to understand these concepts if one wants to then start looking at GD and Phase charts to closely understand what the detailed situation is. These are questions though for someone like me who just wants to understand better an have fun making large and small changes and evaluating the impact of them, both in the measurements and in the sound quality.

I have tested hundreds of different XO filter combinations and various timing options. There are often noticiable audible changes that are rather difficult to explain when looking at the various charts. Interestingly, my preferences are different than what I understand most common recommendations cite. I am now way OT so we should move this elsewhere if you are interested in these more esoteric topics.


----------



## aackthpt

jtalden said:


> I have tested hundreds of different XO filter combinations and various timing options. There are often noticiable audible changes that are rather difficult to explain when looking at the various charts. Interestingly, my preferences are different than what I understand most common recommendations cite. I am now way OT so we should move this elsewhere if you are interested in these more esoteric topics.


Interested, definitely. Please PM me more details if you have the time. Thanks!


----------



## THX-UltraII

Hi John,

I have some new information:
I think I got the timing reference loopback worked but I don t know how to check this. I found out that I had to choose a time ref.output and timeref.input in the soundcard preferences. I chose both my LEFT there. Only problem is that I still don t understand exactly what I can do myself with this option 

I also did a few new measurements. The first mdat I will post a link to at the bottom of this reply is a measurement with 3 measurements. With ALL the 3 measurements I have my AVR [email protected] and my subwoofer on FULL RANGE. The only thing the measurements are different in are the FRONT RIGHT distance settings: Graph 1 is FRONT RIGHT [email protected] (originally measured by audyssey), Graph 2 is the distance with your m12 scenario (so FRONT [email protected]) and Graph 3 is a measurement I did myself that looks to me to be even better then Graph 2 ([email protected] is smaller then this dip in Graph 2). The measurement in Graph 3 is done with a distance of 6.25m of the FRONT RIGHT speaker. 
What I want to find out (myself with your help if possible) is if Graph 3 is indeed better then Graph 2 and I also would like to find out (also myself if possible) is how I can see if timing and phase are ok with this Graph.

Or maybe I don t have to do anything at all anymore and is this just good to go.......

Here s the measurement in .mdat format:
http://www.sendspace.com/file/6koqxm


----------



## THX-UltraII

I also just generated a EXCESS GROUP DEPLAY graph for the settings chosen in Graph 3 (subwoofer 4.25m and front right 6.25m).

Just like REWs manual I took 20,1000 and -100,300 for limits. The problem is that I dont know WHAT information I can gather with this graph. I ve read the 'minimum phase' chapter of the manual a few times now but I just don t get it .

The only thing I do understand is that I can see if there is a delay between the sub and front speakers. If I read correct there is a time difference when the sound arrives at the mic between the subwoofer and main right channel. eg: a 25Hz subwoofer signal is approx. 30ms delayed compared to a 450Hz main right channel signal. Am I reading this correct?

(ps. Also attached the .mdat file)


----------



## jtalden

THX-UltraII said:


> Hi John,
> 
> I have some new information:
> I think I got the timing reference loopback worked but I don t know how to check this. I found out that I had to choose a time ref.output and timeref.input in the soundcard preferences. I chose both my LEFT there. Only problem is that I still don t understand exactly what I can do myself with this option


Yes, it's working now.



> I also did a few new measurements. The first mdat I will post a link to at the bottom of this reply is a measurement with 3 measurements. With ALL the 3 measurements I have my AVR [email protected] and my subwoofer on FULL RANGE. The only thing the measurements are different in are the FRONT RIGHT distance settings: Graph 1 is FRONT RIGHT [email protected] (originally measured by audyssey), Graph 2 is the distance with your m12 scenarios that (so FRONT [email protected]) and Graph 3 is a measurement I did myself that looks to me to be even better then Graph 2 ([email protected] is smaller then this dip in Graph 2). The measurement in Graph 3 is done with a distance of 6.25m of the FRONT RIGHT speaker.
> What I want to find out (myself with your help if possible) is if Graph 3 is indeed better then Graph 2 and I also would like to find out (also myself if possible) is how I can see if timing and phase are ok with this Graph.


Yes, Graph 3 is the alignment I would choose. You can now measure the SW, FR, and SW+FR. then look at relative offset of the SW and FR IRs to confirm they align with each other as my m12 predicted. Then proceed to align the other channels.

BUT...
Since you mention you have Audyssey you have a larger issue to contend with. 
I know that if Audyssey is rerun it will automatically realign all the speaker distances. 
I believe any manual change in the speaker distance will automatically turns Audyssey off so the Audyssey EQ will not function with the distances changes you made. The Audyssey light on the AVR front panel is now out correct?
So, if you want Audyssey EQ you must accept the speaker distances Audyssey sets.
This why I recommend those with Audyssey just run it first and then modify with the Behringer after that if there is dissatisfaction with Audyssey bass response. 
Audyssey sets the distances based on the first mic position, so you may want to move the LP position or the speakers a little and see if Audyssey still provides the erroneous distance settings. Audyssey may also provide a correct distance alignment if you change the SW polarity.
Oh, there is also the option of using the SW variable mode 160 as you did before to make the change without Audyssey knowing it. I hope I am not the last to understand why you did this in the first place! :doh:


----------



## jtalden

Sander,

My apologies!

I posted above.

“
> Distance settings changes found in this experiment:
- m11 decreases the FR distance 3.44 m
- m12 increases the FR distance 2.75 m
- m14 decreases the FR distance 0.34 m (SW polarity must also be changed)
“

This was in error - These directions are reversed. It should read:
- m11 increases the FR distance 3.44 m
- m12 decreases the FR distance 2.75 m
- m14 increases the FR distance 0.34 m (SW polarity must also be changed)

Increasing the distance in the AVR reduces the time delay and I am moving the SW and not the FR when I am doing the calculation thus I sometimes get confused on the relative direction the FR needs to move in distance. I tried to be careful, but it is not unusual for me to get this backwards. 

The net result of the error is that the alignment you found by moving the FR to a greater distance is the conventional alignment, the one I called m11. The relative positions of the SW IR to the FR IR will look more like my m11 IR chart than the m12 you were intended to set. Looking at the GD in your last file was what tipped me off as to my mistake. 

I hope you head doesn’t explode. :R


----------



## THX-UltraII

> .......then look at relative offset of the SW and FR IRs to confirm they align with each other........


And this is exactly the part which I just don t understand WHAT I am actually doing there and HOW do I do this. (sorry m8 for beeing so noobish!)



> Since you mention you have Audyssey you have a larger issue to contend with.


No, I don t use Audyssey. I only used the auddysey once (2 weeks ago) to get the basic speaker distances to work from. Everything else Auddysey did (EQ, settings CO, settings speakers on small/large etc was DISABLED by me immediately)


----------



## THX-UltraII

jtalden said:


> Sander,
> 
> My apologies!
> 
> I posted above.
> 
> “
> > Distance settings changes found in this experiment:
> - m11 decreases the FR distance 3.44 m
> - m12 increases the FR distance 2.75 m
> - m14 decreases the FR distance 0.34 m (SW polarity must also be changed)
> “
> 
> This was in error - These directions are reversed. It should read:
> - m11 increases the FR distance 3.44 m
> - m12 decreases the FR distance 2.75 m
> - m14 increases the FR distance 0.34 m (SW polarity must also be changed)
> 
> Increasing the distance in the AVR reduces the time delay and I am moving the SW and not the FR when I am doing the calculation thus I sometimes get confused on the relative direction the FR needs to move in distance. I tried to be careful, but it is not unusual for me to get this backwards.
> 
> The net result of the error is that the alignment you found by moving the FR to a greater distance is the conventional alignment, the one I called m11. The relative positions of the SW IR to the FR IR will look more like my m11 IR chart than the m12 you were intended to set. Looking at the GD in your last file was what tipped me off as to my mistake.
> 
> I hope you head doesn’t explode. :R


Yep, my head DOES explode John! O men, I just don t understand it anymore. Read this reply 10 times now but I just dont understand it. Are you saying that I have to play with the FRONT RIGHT distance again to look for an even smoother curve or is the 6.25m I found now good to go?

Can you also come back on my post #151 please:

_I also just generated a EXCESS GROUP DEPLAY graph for the settings chosen in Graph 3 (subwoofer 4.25m and front right 6.25m).

Just like REWs manual I took 20,1000 and -100,300 for limits. The problem is that I dont know WHAT information I can gather with this graph. I ve read the 'minimum phase' chapter of the manual a few times now but I just don t get it .

The only thing I do understand is that I can see if there is a delay between the sub and front speakers. If I read correct there is a time difference when the sound arrives at the mic between the subwoofer and main right channel. eg: a 25Hz subwoofer signal is approx. 30ms delayed compared to a 450Hz main right channel signal. Am I reading this correct?_

Really appreciate your patience you have with me John.


----------



## jtalden

THX-UltraII said:


> I also just generated a EXCESS GROUP DEPLAY graph for the settings chosen in Graph 3 (subwoofer 4.25m and front right 6.25m).
> 
> Just like REWs manual I took 20,1000 and -100,300 for limits. The problem is that I dont know WHAT information I can gather with this graph. I ve read the 'minimum phase' chapter of the manual a few times now but I just don t get it .
> 
> The only thing I do understand is that I can see if there is a delay between the sub and front speakers. If I read correct there is a time difference when the sound arrives at the mic between the subwoofer and main right channel. eg: a 25Hz subwoofer signal is approx. 30ms delayed compared to a 450Hz main right channel signal. Am I reading this correct?
> 
> (ps. Also attached the .mdat file)


Yes, 30 ms is a good estimate. 
Maybe your wording is not technically correct, but I think that is the way EDG is thought of and is most often used in practice for convenience. The chart shows that there is a smooth transition from the main speaker to the SW in terms of timing. That also means 90 Hz frequencies from the SW and the FR arrive at the same time and that is about 5 ms after the HF arrival. The SW and FR are in phase at 90 deg. [The Bulge in the trace at 90 is only an artifact of a room mode in this particular case – see below.]

Note also that, for convenience REW can estimate the IR delay and you can apply that shift. That should place the IR peak at 0 ms. The EGD of the HF will now fall at 0 ms. The arrival timing of the HF becomes our reference time. This just makes it easier to read the delay difference for any frequency directly on the scale. That is how the chart is normally presented.

Then the fun starts.
Since these measurements include room response as well as speaker response, the GD and EGD are influenced by reflections and room modes that distort the traces from the trace that is our interest here, that is, the trace of the first sound arrival.
I suggest you experiment with the IR window settings to learn the impact on GD and EGD. Set the left window at 1 and right window and various settings to see the impact of the settings on the traces. It is educational. Here is my chart of your measurement with windowing selected to best see what is going on at the XO.









[Just an obscure note, if you make a room measurement with the IR timing set to my m12 alignment and want to window the GD, the left window needs to be set to 10 ms in order not to window out some of the bass signal. That’s because the SW signal will be leading the FR signal by that much.]


----------



## jtalden

THX-UltraII said:


> And this is exactly the part which I just don t understand WHAT I am actually doing there and HOW do I do this. (sorry m8 for beeing so noobish!)


You have properly found one of the correct alignments; Post 150, trace 3, FR distance of 6.25m. I believe this alignment is the one I called m11 in Fig3b of post 140. 

Since you provided only the SW+FR SPL trace and not the SW and FR measurements individually, I cannot confirm that. I am only ~90% sure it is. To confirm it you would need to recreate the same IR overlay chart that I provided as Fig3b in post 140 – Turn loopback on, measure the SW, FR and SW+FR. Then open the overlay window and select the Impulse tab. Scale the chart as I did and make sure the SW and FR measurements are checked at the bottom of the chart. The SW+FR measurement box is not checked for this purpose, but it won’t hurt anything if it is. That IR chart will now look like either my Fig3b or possibly like my Fig3c in post 140. Either way it is an acceptable alignment. Does this help? 

You don’t have to confirm which one it is if you don’t care. It is one of the 2 optimized alignments so you can just move ahead with next steps if you like.

[My correction was just to point out my mistake in case it was creating confusion for you or for someone else. It was not intended to suggest that you had not found an acceptable setting.]



> No, I don t use Audyssey. I only used the auddysey once (2 weeks ago) to get the basic speaker distances to work from. Everything else Auddysey did (EQ, settings CO, settings speakers on small/large etc was DISABLED by me immediately)


Great all this work wasn’t for nothing!


----------



## THX-UltraII

Thanks John



> Yes, 30 ms is a good estimate.
> Maybe your wording is not technically correct, but I think that is the way EDG is thought of and is most often used in practice for convenience. The chart shows that there is a smooth transition from the main speaker to the SW in terms of timing.


When I look at the example in the manual of REW I see the Excess group delay graph I post as pic1. The manual of REW says this about it:
_''As an aside, the excess group delay plot also clearly shows there is a time offset between the subwoofer and the main speaker, the sub being about 25ms delayed, which is not so obvious from the overall group delay plot. Excess group delay is a useful plot for time aligning speakers''_

Are you saying that at my GED graph the line from 20 to approx 120Hz is a nice sloping line so that this is good? But isn t this line supposed to be horizontal all the way from 20Hz and up at the same ms? (which means no delay?) 
What I think now (and maybe this is where I m missing something) is that I would have to CHANGE the distance setting of my subwoofer to compensate this 30ms difference in order to let it be a perfect line from 20Hz and up at the same ms value. But of course if this would be true my dips in the ALL SPL chart will change in a negative way then and this is also what I not want..... 
It confuses me! 



> Note also that, for convenience REW can estimate the IR delay and you can apply that shift. That should place the IR peak at 0 ms. The EGD of the HF will now fall at 0 ms. The arrival timing of the HF becomes our reference time. This just makes it easier to read the delay difference for any frequency directly on the scale. That is how the chart is normally presented.


Ok, what I did is click on 'estimate IR delay' in the SLP&Phase chart. Although I don t exactly understand WHAT happens when doing that (maybe you can explain this one more time in simple plain noobtext?) my HF (High Frequencies you mean with this I assume?) in the EGD graph went to exactly 0.

What I then did is I drew an imaginary line as you see in pic2. I will post. I did this because you say that the peaks do not matter (what are the peaks give me for information than?). If I am correct (and I hope I am) the imaginary red line I drew is the so called minimum phase? When I look at the 90Hz freq. then I see that there is a delay of approx 7ms when comparing it to the high frequencies correct?



> Since these measurements include room response as well as speaker response, the GD and EGD are influenced by reflections and room modes that distort the traces from the trace that is our interest here, that is, the trace of the first sound arrival.


Understand this



> I suggest you experiment with the IR window settings to learn the impact on GD and EGD. Set the left window at 1 and right window and various settings to see the impact of the settings on the traces. It is educational. Here is my chart of your measurement with windowing selected to best see what is going on at the XO.


I did the eaxt same as you did (went from pic3. to pic4. which is Left Window from 125 to 1 and Right Window from 500 to 26 just like you did) but I get a totally different outcome as the graph you posted as you can see :huh: 
And for changing these settings I have the same problem: I still don t know WHAT actaully happs with these so called 'window' changes..... (So sorry John, please dont give up on me yet :sad



> Just an obscure note, if you make a room measurement with the IR timing set to my m12 alignment and want to window the GD, the left window needs to be set to 10 ms in order not to window out some of the bass signal. That’s because the SW signal will be leading the FR signal by that much.


And because I need to understand things better first I also don t understand this quote.

Again John, I m trying the best I can but I m a sales manager and physics was not my best thing in high school as you might noticed  But don t give up on me.

This post took me 2 hours. Going to bed now and see what tomorrow brings. Later John.


----------



## THX-UltraII

> Since you provided only the SW+FR SPL trace and not the SW and FR measurements individually, I cannot confirm that. I am only ~90% sure it is. To confirm it you would need to recreate the same IR overlay chart that I provided as Fig3b in post 140 – Turn loopback on, measure the SW, FR and SW+FR. Then open the overlay window and select the Impulse tab. Scale the chart as I did and make sure the SW and FR measurements are checked at the bottom of the chart. The SW+FR measurement box is not checked for this purpose, but it won’t hurt anything if it is. That IR chart will now look like either my Fig3b or possibly like my Fig3c in post 140. Either way it is an acceptable alignment. Does this help?


John, I will do these measurements (learning process for me again) tomorrow and you have have new information (and questions but let hope the questions will get less and I will understand things better from post to post) by tomorrow night.


----------



## jtalden

Sander,
I can answer all of these Q’s and will do that if you like. I have been doing that because I originally understood that you wanted a better understanding, you were up for a learning experience and you were willing to take lots of measurements. I’m still willing to support that. 

With your level of understanding I warned you that addressing GD / EGD would lead to more confusion than you are ready for. I now sense you are getting impatient and ready to set the distance correctly and move on. 

*I can’t understand why you would want to actually use your theater!* 

Let me summarize the situation as I understand it.

> The SPL response using the AVR XO and distance settings was originally not providing the best SPL in the XO range. I postulated that with the correct distance settings it will do just that without using the SW phase settings.

> I calculate there are 2 settings of speaker distance with the current SW polarity (and one with inverted SW polarity) that will achieve a similar SPL chart and are acceptable in that regard. You have now found one of them. I believe it to be m11.

> I mentioned the SW and FR will be substantially in phase through the XO range with any of the 3 setting, m11, m12, m14.

> I also mentioned that the 3 settings have pros and cons (engineering tradeoffs) that I can try list (but will confuse you more) including impact on EGD. (I also don’t think there is expert agreement as to which setting is best.) I also mentioned I would expect them to sound a little different to you.

> I suggested that you may want to try m12 [It does in fact move the SW EGD downward.] I also state now that there no setting that will result in a 0 ms EGD across the full SW range. There will also be no setting that minimizes the EGD to 0 ms that will also provide the best SPL output. You may well be as bad off for SPL as where you started if you try to do that.

So it’s time to decide where you want to go from here:

> Move forward using the current distance setting.

> Change to the m12 type alignment and then move forward.

> Have me answer your questions above to continue to work to a better understanding. 
[Before we do this one, I insist that you provide the IR chart of showing the current timing. I detailed how again above. [Otherwise some of my comments are somewhat suspect.]

> Other?

[I hesitate to mention this >> With some more work we may be able to identify a distance setup that would allow you switch between m11 and m12 with just a SW distance change. That would make it easy for you to switch back and forth between the 2 timings and see which you prefer for sound.]

I’m will continue to help the XO/Distance questions At least for a while, but I will bailout once that is resolved to your satisfaction.


----------



## THX-UltraII

Goodmorning John,



> I can answer all of these Q’s and will do that if you like. I have been doing that because I originally understood that you wanted a better understanding, you were up for a learning experience and you were willing to take lots of measurements. I’m still willing to support that.


You understand this correct John: I m willing to learn and do as much measurements as needed! If you would like to come back on all my questions in post #158 from last night I THINK (and hope) that I will understand things better.



> With your level of understanding I warned you that addressing GD / EGD would lead to more confusion than you are ready for. I now sense you are getting impatient and ready to set the distance correctly and move on.*I can’t understand why you would want to actually use your theater!*


John, I don t mind if this learning curve takes weeks or even more. I really don t!



> > The SPL response using the AVR XO and distance settings was originally not providing the best SPL in the XO range. I postulated that with the correct distance settings it will do just that without using the SW phase settings.


understand



> > I calculate there are 2 settings of speaker distance with the current SW polarity (and one with inverted SW polarity) that will achieve a similar SPL chart and are acceptable in that regard. You have now found one of them. I believe it to be m11.


understand



> > I mentioned the SW and FR will be substantially in phase through the XO range with any of the 3 setting, m11, m12, m14.


How can you see per measurement if the XO range is in phase? (Do you see this with the EGD graph?)



> > I also mentioned that the 3 settings have pros and cons (engineering tradeoffs) that I can try list (but will confuse you more) including impact on EGD. (I also don’t think there is expert agreement as to which setting is best.) I also mentioned I would expect them to sound a little different to you.


understand



> > I suggested that you may want to try m12 [It does in fact move the SW EGD downward.] I also state now that there no setting that will result in a 0 ms EGD across the full SW range. There will also be no setting that minimizes the EGD to 0 ms that will also provide the best SPL output. You may well be as bad off for SPL as where you started if you try to do that.


Understand. But what is better: have a 0ms EDG across the full range from 20-20000 or have a flatter SPL response? And IS both even possible anyway?



> So it’s time to decide where you want to go from here:
> > Move forward using the current distance setting.
> > Change to the m12 type alignment and then move forward.


I don t mind which to choose but as you might have noticed in my post #158 I first want to know and understand more.



> > Have me answer your questions above to continue to work to a better understanding.
> [Before we do this one, I insist that you provide the IR chart of showing the current timing. I detailed how again above. [Otherwise some of my comments are somewhat suspect.]


Will do this in about 2 hours. I will have plenty of time then.



> [I hesitate to mention this >> With some more work we may be able to identify a distance setup that would allow you switch between m11 and m12 with just a SW distance change. That would make it easy for you to switch back and forth between the 2 timings and see which you prefer for sound.]


Maybe for later if I understand everything 100%?



> I’m will continue to help the XO/Distance questions At least for a while, but I will bailout once that is resolved to your satisfaction.


Thanks again for this John! If you want a little PayPal donation for your help let me know!


----------



## THX-UltraII

THX-UltraII said:


> John, I will do these measurements (learning process for me again) tomorrow and you have have new information (and questions but let hope the questions will get less and I will understand things better from post to post) by tomorrow night.


So proud of myself I was able to do my homework as you assigned for me John! 

Let s see if you can explain to me (again? ) WHAT information this graph gives me.

I ve also attachted the SW, FR and SW+FR .mdat


----------



## jtalden

THX-UltraII said:


> So proud of myself I was able to do my homework as you assigned for me John!
> 
> Let s see if you can explain to me (again? ) WHAT information this graph gives me.
> 
> I ve also attachted the SW, FR and SW+FR .mdat


Great job measuring! 
I just noticed you have a very quiet theater. I’m jealous!

The measurement looks as expected. This is the alignment that I referred to as m11. Good, now we know for sure.

The IR chart shows us:
> The HF (in this case the range from say 5k -20k Hz) arrival time at the LP is about 17.7 ms after the signal is sent from REW. That is shown by the arrival time of the initial, highest peak for the FR speaker. [The lower frequencies of the FR, including the 40 – 90 Hz range are arriving at the LP delayed somewhat, but we can see that directly in this IR chart.]
> The HF portion of the SW (100-200 Hz?) arrival time at the LP is maybe 35 ms after the signal is sent from REW. That is shown by the arrival time of the first, large peak for the SW. [Again, the lower frequencies of the SW are arriving at the LP delayed somewhat, but we can see that directly in IR chart.]
> Most of that delay is due to the time of flight of the wave from the speaker and the delays that are added due to the distance setting in the AVR.
> The “noise” in IR after the direct signal has arrived is due to room response and other factors not worth mentioning.
> It’s tempting to think that all we need to do is align the IR peaks for the proper timing, but that is not correct. That alignment is a convenient starting point to find an alignment that fits the situation however. I started my calculation exercise with the IR aligned and found that the SPL response was poor as the phase was not favorably aligned. I then shifted the minimum necessary to each direction to find alignment that maximized the SPL in the 40-90 Hz range as that was the chosen priority or issue in this particular case.
> If this is the only chart you look at that is about all you can say. It is critical however to determine where to start the time alignment process.

From the measurement file attached we can also make these observations:
> The acoustic XO range is marked on the SPL chart below. The range extends (generously) from about 30 – 200 Hz where the SPL of one of the speakers is down 30 dB. (20 dB down is probably good enough to use.)
> This m11 timing alignment maximizes the SPL output from 40 – 90 Hz (where we needed the SPL help). This was our first chosen priority.
> This also means the phase alignment is optimized in this range. [Phase is not aligned as well above 100 Hz as that would push up the SPL response in that area. That would be counterproductive to leveling the SPL in our case.]
> The GD/EGD is not minimized, or perfectly aligned, but it is reasonably aligned in a commonly found manner. A 65 Hz direct signal will arrive at the LP at roughly the same amplitude and time from both the FR and SW. [Yes, that time is delayed several ms from the reference HF arrival time. The exact number of the offset is difficult to determine with precision, not important (considering we chose to optimize the SPL) and it’s also beyond the scope here.]

Figd1








Figd2


----------



## jtalden

THX-UltraII said:


> Thanks John
> 
> When I look at the example in the manual of REW I see the Excess group delay graph I post as pic1. The manual of REW says this about it:
> _''As an aside, the excess group delay plot also clearly shows there is a time offset between the subwoofer and the main speaker, the sub being about 25ms delayed, which is not so obvious from the overall group delay plot. Excess group delay is a useful plot for time aligning speakers''_
> 
> Are you saying that at my GED graph the line from 20 to approx 120Hz is a nice sloping line so that this is good? But isn t this line supposed to be horizontal all the way from 20Hz and up at the same ms? (which means no delay?)


A horizontal line is not possible with your system, or mine, or any “conventional” setup. All dynamic speakers and SWs have phase rotation and GD shifts that prevents obtaining a flat GD/EGD line. There are a few methods to get there, but you and I don’t have that capability. Those systems would pass a perfect square wave, but they still can have significant tradeoffs in other respects. 



> What I think now (and maybe this is where I m missing something) is that I would have to CHANGE the distance setting of my subwoofer to compensate this 30ms difference in order to let it be a perfect line from 20Hz and up at the same ms value. But of course if this would be true my dips in the ALL SPL chart will change in a negative way then and this is also what I not want...


I am saying that this m11 is one normal alignment. One that I have found Audyssey to set for example. It is a sensible one in that the if you have 80 Hz XO frequency, an 80 Hz signal from REW or other source will arrive at the LP at the same time and in phase from both speakers. 

My m12 alignment will reduce the SW delay and move it toward zero. It also have the effect that an 80 Hz signal will arrive at the LP from the SW one wavelength (12.5 ms) ahead of the same signal from the FR. They will still be in phase and the SPL will still be the same so that is an acceptable alignment also. It's easy to make this change and see the results. I suggested this alignment as possibly better for the GD reason and my own listening comparisons. Again, they will sound different in my setup, but I cannot say one is really better.



> Ok, what I did is click on 'estimate IR delay' in the SLP&Phase chart. Although I don t exactly understand WHAT happens when doing that (maybe you can explain this one more time in simple plain noobtext?) my HF (High Frequencies you mean with this I assume?) in the EGD graph went to exactly 0.


Look now at the IR chart to see what happened. The IR peak was shifted from around +17.6 ms to 0 ms. 

For calculation and charting purposes REW needs to have a time reference for some of the charts. It will not affect the SPL chart unless you have applied a narrow window setting applied to it. For most charts you want the IR at zero. For the purpose of IR arrival timing (distance settings) we want to see real time so that we can see the relative offset between SW and main speaker. IF they both are shifted to 0 ms automatically by REW we lose that ability.




> I did the eaxt same as you did (went from pic3. to pic4. which is Left Window from 125 to 1 and Right Window from 500 to 26 just like you did) but I get a totally different outcome as the graph you posted as you can see :huh:
> And for changing these settings I have the same problem: I still don t know WHAT actaully happs with these so called 'window' changes...


After changes to the window setting box you need to both select “Apply Windows” (you did that) and also “Generate Minimum Phase” (find it in the controls window).


----------



## THX-UltraII

> I just noticed you have a very quiet theater. I’m jealous!


Thank John. Where did you see this? At the RT60 and waterfall graphs?



> The measurement looks as expected. This is the alignment that I referred to as m11. Good, now we know for sure.


I see that too

I m afraid I have to give up John. Your new reply confuses me more and more . Let s see:



> > The HF (in this case the range from say 5k -20k Hz) arrival time at the LP is about 17.7 ms after the signal is sent from REW. That is shown by the arrival time of the initial, highest peak for the FR speaker.


I see that the green (MAIN RIGHT) has a large peak from approx. -38 to 100%FS but I don t know what that -38 to 100%FS says. And how do you know that this is the 5k-20Khz range?? And I also just don t know yet what that 17.7ms says. What is LP? Low Pass? And you say ''......after the signal is sent from REW''. Why do we want to know that? We want to know what time a signal takes from the moment it leaves my speaker don t we?



> [The lower frequencies of the FR, including the 40 – 90 Hz range are arriving at the LP delayed somewhat, but we can see that directly in this IR chart.]


How do you see that?



> > The HF portion of the SW (100-200 Hz?) arrival time at the LP is maybe 35 ms after the signal is sent from REW. That is shown by the arrival time of the first, large peak for the SW.


I see the first red peak at 35ms but again, how do you know that these are the 100-200Hz frequencies?



> [Again, the lower frequencies of the SW are arriving at the LP delayed somewhat, but we can see that directly in IR chart.]


Not seeing that..... 



> > Most of that delay is due to the time of flight of the wave from the speaker and the delays that are added due to the distance setting in the AVR.


understand what you are saying here



> > The “noise” in IR after the direct signal has arrived is due to room response and other factors not worth mentioning.


what noise?



> > It’s tempting to think that all we need to do is align the IR peaks for the proper timing, but that is not correct. That alignment is a convenient starting point to find an alignment that fits the situation however. I started my calculation exercise with the IR aligned and found that the SPL response was poor as the phase was not favorably aligned. I then shifted the minimum necessary to each direction to find alignment that maximized the SPL in the 40-90 Hz range as that was the chosen priority or issue in this particular case.
> > If this is the only chart you look at that is about all you can say. It is critical however to determine where to start the time alignment process.


Dont understand it even after reading this more than 20 times now...... :huh:



> From the measurement file attached we can also make these observations:
> > The acoustic XO range is marked on the SPL chart below. The range extends (generously) from about 30 – 200 Hz where the SPL of one of the speakers is down 30 dB. (20 dB down is probably good enough to use.)


Let me see if I understand this: when I would take 20dB down, the acoustic XO range would be just a little bit smaller so approx. from 40 - 180 Hz



> > This m11 timing alignment maximizes the SPL output from 40 – 90 Hz (where we needed the SPL help). This was our first chosen priority.


don t understand this.



> > This also means the phase alignment is optimized in this range. [Phase is not aligned as well above 100 Hz as that would push up the SPL response in that area. That would be counterproductive to leveling the SPL in our case.]


I can see this from the Phase chart you created (where can I make that chart?) correct? I see that the two lines (front and subwoofer) are close to each other in the XO range but not close to each other outside that range but that does not matter because it s not the Xover range anymore and you cannot hear that because below 40Hz the sound comming from the front is neglectable and above 90-100Hz the sound comming from the subwoofer is neglectable.



> > The GD/EGD is not minimized, or perfectly aligned, but it is reasonably aligned in a commonly found manner. A 65 Hz direct signal will arrive at the LP at roughly the same amplitude and time from both the FR and SW. [Yes, that time is delayed several ms from the reference HF arrival time. The exact number of the offset is difficult to determine with precision, not important (considering we chose to optimize the SPL) and it’s also beyond the scope here.]


understand this

As you can see too many things I do not understand. If you quite trying to help me understand I will not blame you at all John. I m afraid my capability of understanding how things work in REW and with sound are just not good enough (I m ashamed and don t understand myself because I m not a stupid person you know :scratch


----------



## THX-UltraII

> A horizontal line is not possible with your system, or mine, or any “conventional” setup. All dynamic speakers and SWs have phase rotation and GD shifts that prevents obtaining a flat GD/EGD line. There are a few methods to get there, but you and I don’t have that capability. Those systems would pass a perfect square wave, but they still can have significant tradeoffs in other respects.


understand



> I am saying that this m11 is one normal alignment. One that I have found Audyssey to set for example. It is a sensible one in that the if you have 80 Hz XO frequency, an 80 Hz signal from REW or other source will arrive at the LP at the same time and in phase from both speakers.
> 
> My m12 alignment will reduce the SW delay and move it toward zero. It also have the effect that an 80 Hz signal will arrive at the LP from the SW one wavelength (12.5 ms) ahead of the same signal from the FR. They will still be in phase and the SPL will still be the same so that is an acceptable alignment also. It's easy to make this change and see the results. I suggested this alignment as possibly better for the GD reason and my own listening comparisons. Again, they will sound different in my setup, but I cannot say one is really better.


completely understand this!



> Look now at the IR chart to see what happened. The IR peak was shifted from around +17.6 ms to 0 ms.
> 
> For calculation and charting purposes REW needs to have a time reference for some of the charts. It will not affect the SPL chart unless you have applied a narrow window setting applied to it. For most charts you want the IR at zero. For the purpose of IR arrival timing (distance settings) we want to see real time so that we can see the relative offset between SW and main speaker. IF they both are shifted to 0 ms automatically by REW we lose that ability.


understand! (hey, this goes a lot better then my other reply )



> After changes to the window setting box you need to both select “Apply Windows” (you did that) and also “Generate Minimum Phase” (find it in the controls window).


Ok, but what information do I get by changing these windows settings?


----------



## THX-UltraII

long day @work tomorrow so going to bed now. I ll read your replies tomorrownight and see if you re mad at me for not understanding a lot of the new things you tried to teach me.:innocent:


----------



## jtalden

THX-UltraII said:


> Where did you see this? At the RT60 and waterfall graphs?


No, I got it by looking at the last SPL overlay. The SPL roll off of the SW and FR traces don’t run into the noise floor until 35 dB or so. You can easily measure the noise floor by taking a measurement without any signal to the speakers (just turn the AVR off). Yours will look very good.



> <clip>
> 
> I see that the green (MAIN RIGHT) has a large peak from approx. -38 to 100%FS but I don t know what that -38 to 100%FS says. And how do you know that this is the 5k-20Khz range?? And I also just don t know yet what that 17.7ms says. What is LP? Low Pass? And you say ''......after the signal is sent from REW''. Why do we want to know that? We want to know what time a signal takes from the moment it leaves my speaker don t we?


LP is usually the “Listening Position” on all these audio forums unless it is clear that the context is filters where “Low Pass” would make sense. LPF for Low Pass Filter would be preferred to avoid confusion. The LP is where we tell you to put the mic. Where did you put your mic?  [Please don't tell me where to put mine.]

The measurement signal originates from REW and passes through several devices including the speakers before it travels as an audio signal to the mic at the LP, then again as an electrical signal back into REW. With loopback engaged the IR time is the difference in time between the arrival of loopback signal and the mic signal. So if the loopback comes before the AVR the time includes the delay in the AVR. That is not a problem for us when the job is setting the relative speaker distances properly.

This entire exercise is concerned with optimizing the difference in time that the signal arrives at the LP for the SW verses the FR main speaker.

You can just take it as a fact the initial large peak of the IR is representative of the time at which the “HF” portion of the sound arrives for the speaker. Be mindful that what is HF for a SW is normally called bass or LF in most all other cases, but it is still the highest freq that the SW reproduces. You will not be measuring any sound at 10k Hz using only a SW so the IR peak can’t represent arrival time of 10k Hz! So the initial large peak in the SW IR can be thought to represent maybe the frequencies on the SPL chart where just before the SPL rolls off, maybe around 100 Hz in your case.

The 5k - 20k range I mentioned for the FR is just a nice safe number to give you to understand of what to think of when I said “HF” for that speaker. There is nothing magic about the pick except that I know the arrival time of that entire range of frequencies can be thought of as equal as there will miniscule GD change in that range. The nearer to the LF range (90 Hz for that speaker) The greater the GD/EGD will be.

The “-38 to 100%FS” Means nothing to us in this context. It is the time delay of the initial peak that is of interest no matter the magnitude it has.



> How do you see that


This should have said “cannot see that in the IR chart”. I just lost the negative somehow.



> I see the first red peak at 35ms but again, how do you know that these are the 100-200Hz frequencies?


Per above.



> Not seeing that.....


Again I intended to type “we cannot see that in the IR chart” I copied and pasted the phrase from above so when the negative was missing above it was missing here also. I will have to discuss this with my editor, but first a glass of wine 



> <clip>
> 
> what noise?


Sorry, I was referring to all the hash that occurs in the IR trace after that initial IR peak. You may want to find an IR of a clean electrical signal or a speaker in an anechoic situation to see that it has just one peak.



> Dont understand it even after reading this more than 20 times now...... :huh:


I guess you need a better teacher.  I think you said you understand it your following post though so maybe it got through.



> Let me see if I understand this: when I would take 20dB down, the acoustic XO range would be just a little bit smaller so approx. from 40 - 180 Hz


Yes, How much the relative signal needs to be attenuated to make its effect trivial is a matter of opinion. Maybe 15 dB is enough?



> don t understand this.


I’m lost here. You don’t understand that we started out trying to maximize the SPL output in 40 - 90 Hz range to help fill the dip you have there? We did not say we wanted to align the phase at 90 deg or minimize the SW GD/EDG or...


----------



## jtalden

THX-UltraII said:


> understand
> 
> completely understand this!
> 
> understand! (hey, this goes a lot better then my other reply )
> 
> 
> Ok, but what information do I get by changing these windows settings?


Just a feel for the impact of the window settings on the GD/EGD. You will quickly learn it is not easy to pin down the delays accurately.


----------



## Barleywater

> A horizontal line is not possible with your system, or mine, or any “conventional” setup. All dynamic speakers and SWs have phase rotation and GD shifts that prevents obtaining a flat GD/EGD line. There are a few methods to get there, but you and I don’t have that capability. Those systems would pass a perfect square wave, but they still can have significant tradeoffs in other respects.


Please pass the square waves:

Here is very conventional system 5.25 inch woofer, 2 inch full range as tweeter. Crossover is 1kHz with DCX2496. Two dynamic drivers and electronic crossover, really no different than SW and FR here with AVR as crossover.

Raw system response:

 

Much as filters from REW may be exported and employed via convolution, I use filter derived by DRC type methods. This is becoming less a departure from "conventional" as more people wrap there heads around it. For each frequency in FFT of system's time domain impulse response, amplitude and phase are adjusted. Computer solves thousands of filters simultaneously.

System after EQ:



I've attached mdat for more thorough look.

Proper understanding of technique and methods makes alignments very straight forward. Multi channel sound cards may be used in place of DCX. For theater there is drawback of often needing lip sync correction via video delay. Some AVRs do this, and some software for htpc will also do this.

The key is real time convolution engine.

Here I posted project with same drivers and sound card in place of crossover. Post includes SW work as well: http://orion.quicksytes.com/viewtopic.php?f=14&t=2254&sid=f29cbbd0474374621f1cbcb7fccd94b9

It includes square wave response pics.

The sound imaging with music is spectacular. Transient behavior is spectacular.

Andrew


----------



## THX-UltraII

> No, I got it by looking at the last SPL overlay. The SPL roll off of the SW and FR traces don’t run into the noise floor until 35 dB or so. You can easily measure the noise floor by taking a measurement without any signal to the speakers (just turn the AVR off). Yours will look very good.


with noise floor you just mean the environment sounds? Is pic1 my noise floor?



> LP is usually the “Listening Position” on all these audio forums unless it is clear that the context is filters where “Low Pass” would make sense. LPF for Low Pass Filter would be preferred to avoid confusion. The LP is where we tell you to put the mic. Where did you put your mic?  [Please don't tell me where to put mine.]
> 
> The measurement signal originates from REW and passes through several devices including the speakers before it travels as an audio signal to the mic at the LP, then again as an electrical signal back into REW. With loopback engaged the IR time is the difference in time between the arrival of loopback signal and the mic signal. So if the loopback comes before the AVR the time includes the delay in the AVR. That is not a problem for us when the job is setting the relative speaker distances properly.


understood



> This entire exercise is concerned with optimizing the difference in time that the signal arrives at the LP for the SW verses the FR main speaker.
> 
> You can just take it as a fact the initial large peak of the IR is representative of the time at which the “HF” portion of the sound arrives for the speaker. Be mindful that what is HF for a SW is normally called bass or LF in most all other cases, but it is still the highest freq that the SW reproduces. You will not be measuring any sound at 10k Hz using only a SW so the IR peak can’t represent arrival time of 10k Hz! So the initial large peak in the SW IR can be thought to represent maybe the frequencies on the SPL chart where just before the SPL rolls off, maybe around 100 Hz in your case.
> 
> The 5k - 20k range I mentioned for the FR is just a nice safe number to give you to understand of what to think of when I said “HF” for that speaker. There is nothing magic about the pick except that I know the arrival time of that entire range of frequencies can be thought of as equal as there will miniscule GD change in that range. The nearer to the LF range (90 Hz for that speaker) The greater the GD/EGD will be.
> 
> The “-38 to 100%FS” Means nothing to us in this context. It is the time delay of the initial peak that is of interest no matter the magnitude it has.
> 
> 
> 
> This should have said “cannot see that in the IR chart”. I just lost the negative somehow.
> 
> 
> 
> Per above.
> 
> 
> 
> Again I intended to type “we cannot see that in the IR chart” I copied and pasted the phrase from above so when the negative was missing above it was missing here also. I will have to discuss this with my editor, but first a glass of wine
> 
> 
> 
> Sorry, I was referring to all the hash that occurs in the IR trace after that initial IR peak. You may want to find an IR of a clean electrical signal or a speaker in an anechoic situation to see that it has just one peak.
> 
> 
> 
> I guess you need a better teacher.  I think you said you understand it your following post though so maybe it got through.
> 
> 
> 
> Yes, How much the relative signal needs to be attenuated to make its effect trivial is a matter of opinion. Maybe 15 dB is enough?
> 
> 
> 
> I’m lost here. You don’t understand that we started out trying to maximize the SPL output in 40 - 90 Hz range to help fill the dip you have there? We did not say we wanted to align the phase at 90 deg or minimize the SW GD/EDG or...


what if I just take the following measurements and get the dips and peaks as good as possible and hear from you if everything is ok:

SW+FRONT LEFT
SW+CENTER
SW+REAR RIGHT
SW+LEFT RIGHT


----------



## jtalden

THX-UltraII said:


> with noise floor you just mean the environment sounds? Is pic1 my noise floor?


Yes



> what if I just take the following measurements and get the dips and peaks as good as possible and hear from you if everything is ok:
> 
> SW+FRONT LEFT
> SW+CENTER
> SW+REAR RIGHT
> SW+LEFT RIGHT


We could do that, but we will likely end up with LP IR timing of each of the main speaker being different from each other. It is better to have the LP IR timing the same for all main speakers. 

We established good IR timing for the FR. I suggest we just replicate that same timing to the other main speakers. (We don't need the SW turned on for this purpose)

The process:
[SW off, Mic at LP, Set Loopback on.]

> Measure FR main speaker. [This is our reference IR timing.]
> Set the FL distance in the AVR same as the FR since the FL speaker is probably about equal distance from the LP. [This is not necessary, but sets the IR timing close to the correct setting]. 
> Measure the FL speaker.
> Zoom in as tight as possible on the 2 IR peaks in the overlay window so we can compare the timing of the FL to the reference timing of the FR. Like this:









> Now adjust (see note below) the FL distance in the AVR and remeasure until the 2 IR peaks fall as closely as possible using the highest zoom setting for the time scale. [When you get the best IR alignment possible you can delete any trial measurements it took to get there. The IR chart should now approach this: 









> Do this for each main speaker - then the final IR overlay chart will come as close to this as possible: 









Because of the limits of the AVR distance settings we will not get all the other IRs to fall directly on top of the FR reference IR as shown here. The objective is just to get them as closely aligned as possible. A small error like 0.1 m, or so is not significant. Just use the AVR distance setting to minimize the error.

Note on adjustments: We can use trial and error to adjust the IR timing or it is possible to measure the IR offset distance using Control Key and right mouse button to click and drag between the IR peaks on the chart as shown above. The cursor indicates the needed adjustment.

Now the IR timings (AVR speaker distance settings) are optimized for all main speakers.

We can now measure the SW+Main for each speaker and overlay the SPL responses. 

Look particularly at the SW+FR SPL in the XO range to confirm that the alignment we have chosen works for the SW+FL as well as the SW+FR. If the SPL looks poor for the SW+FL in the XO range then we may want to revisit the original choice we made of using the SW+FR to establish the target timing. In that case we may find that a compromise may be in order between using the SW+FR optimized timing as the reference and using the SW+FL optimized timing as the reference. Hopefully there will be no significant problem in this respect.
[The XO range of the other main speakers is not as critical as the FL and FR so I would make SW to Main alignment decision based only on the FL and/or FR.]


Keep in mind this method:
> First "Optimized" the target timing using the SW+FR, but that doesn't mean that the SW+FR timing could not have been been done in other ways with equal or better results sonically. It was actually just one good compromize alignment of several possible good alignments.
> Then Optimized the timing alignment of the other main speakers to match the target. This is always a good idea. 

Then it's off to EQ. :sn:


----------



## THX-UltraII

Howly cow I understand your entire reply and all the homework you give me! Tomorrownight new measurement night! You will hear from me soon


----------



## THX-UltraII

Hi John,

I just did a new measurements with your new instructions. I m a bit proud of myself for accomplishing the next screenshot. All credits goes to your help of course!

The red measurement is my FRONT RIGHT and the green is my FRONT LEFT. Am I correct that there is a time difference when the sound arrives at LP of 7.2805ms and that now need to adjust the distance setting of the LEFT SPEAKER in my AVR settings with the result that the large peaks (100% FS) overlap as close as possible?

Hope I m on the right track now. And another question before I move on. After this I will need to measure my CENTER, RIGHT SURROUND and LEFT SURROUND too and adjust them the same as I will have to do for my FRONT LEFT speaker. But *how* do I measure my center, right surround and left surround channels? What I did for my LEFT FRONT measurement was switch the RIGHT AUX IN of my avr to the LEFT AUX IN of my avr which results in the measurement of my left front speaker but what do I do for measuring the center and surrounds?? 

Here s also the .mdat of the right front and left front measurement I just did:
http://www.sendspace.com/file/67yp1w


----------



## aackthpt

THX-UltraII said:


> Hope I m on the right track now. And another question before I move on. After this I will need to measure my CENTER, RIGHT SURROUND and LEFT SURROUND too and adjust them the same as I will have to do for my FRONT LEFT speaker. But *how* do I measure my center, right surround and left surround channels? What I did for my LEFT FRONT measurement was switch the RIGHT AUX IN of my avr to the LEFT AUX IN of my avr which results in the measurement of my left front speaker but what do I do for measuring the center and surrounds??


It sounds like he means for you to only do this on left and right (which would typically be considered the "mains"). Then you just set the center and surrounds by taking physical measurements or possibly using the settings Audyssey figured out originally.

However if you really want to try it on other channels... to get IRs for the others the easiest way is to put your receiver into "7.1 ch input" mode and use the multichannel inputs on the back (pages 21 and 50 in the SR5005 manual). This however does not steer the bass to the subwoofer. I have read on another thread here that if you connect the computer to the AVR with HDMI and use "ASIO4ALL" you can steer the sweep to any channel (this is actually something I intend to try myself), and if you do this then you can keep the AVR in surround mode and it would be processed through bass management as usual. There are probably other ways to do this with some of the community test DVDs that are available, but I'm not entirely sure how one would go about that.


----------



## jtalden

THX-UltraII said:


> Hi John,
> 
> I just did a new measurements with your new instructions. I m a bit proud of myself for accomplishing the next screenshot. All credits goes to your help of course!
> 
> The red measurement is my FRONT RIGHT and the green is my FRONT LEFT. Am I correct that there is a time difference when the sound arrives at LP of 7.2805ms and that now need to adjust the distance setting of the LEFT SPEAKER in my AVR settings with the result that the large peaks (100% FS) overlap as close as possible?
> 
> Hope I m on the right track now. And another question before I move on. After this I will need to measure my CENTER, RIGHT SURROUND and LEFT SURROUND too and adjust them the same as I will have to do for my FRONT LEFT speaker. But *how* do I measure my center, right surround and left surround channels? What I did for my LEFT FRONT measurement was switch the RIGHT AUX IN of my avr to the LEFT AUX IN of my avr which results in the measurement of my left front speaker but what do I do for measuring the center and surrounds??
> 
> Here s also the .mdat of the right front and left front measurement I just did:
> http://www.sendspace.com/file/67yp1w


Sander,
You understand the adjustment of FL correctly. 
The distance of the FL needs to increased by approximately 2.5 m in order to approach the timing of the FR (increasing the distance reduces the time).
You can then zoom in on the new IR timing alignment and see if it overlays closely or if it can be adjusted a little better.

When we have the final alignment we could move on to the other main speakers, but I think is better to stop here and do something else first. It would be best to first measure SW+FL and SW+FR and overlay the SPL results. This will allow us to confirm that the SW+FR timing adjustment we chose also works well for the SW+FL as well. If that looks good then it is time to align the rest of the speakers. 

How we measure CC and surround speakers depends on the equipment capabilities and access. If we have a "Full Mono" mode and can also disconnect speaker wires easily that will work. Place the AVR in Full Mono mode and disconnect all but the main speaker being adjusted.

Using stereo mode we could temporarily attach each main speaker to left front and align the IR's that way. we just need to keep track of the distance values found for each main speaker and then when done reset all the wires and enter the distance values found into the proper speaker channel of the AVR.


----------



## THX-UltraII

Will post results in one hour John! Stay online! :T


----------



## THX-UltraII

aackthpt said:


> I have read on another thread here that if you connect the computer to the AVR with HDMI and use "ASIO4ALL" you can steer the sweep to any channel (this is actually something I intend to try myself), and if you do this then you can keep the AVR in surround mode and it would be processed through bass management as usual


This sounds interesting. Do have a link to this topic?


----------



## THX-UltraII

FRONT [email protected] 6.12m gives me the best result (red line is FRONT RIGHT):



> It would be best to first measure SW+FL and SW+FR and overlay the SPL results. This will allow us to confirm that the SW+FR timing adjustment we chose also works well for the SW+FL as well. If that looks good then it is time to align the rest of the speakers.


10 min and I will post this


----------



## THX-UltraII

I don t think that I have good news. I just measured (.mdat link on bottom of this reply)

Graph 1: subwoofer (4.25m) +front left (6.12m)
Graph 2: subwoofer (4.25m) +front right (6.25m)
Graph 3: no sub, front left (6.12m)
Graph 4: no sub, front right (6.25m)

Am I correct that I can make the conclusion that the SPL overlay of the SUB+FRONT LEFT is by far not as good as the SUB+FRONT RIGHT measurement? Can I also make the conclusion (please correct me if I m wrong) that with this setup (distances settings) in a stereo setup the time that the sound arrives at my LP is perfectly balanced between the LEFT and RIGHT signal (that s why I matched the IR peak as good as possible) but the SPL in the SUB+LEFT FRONT has some dips (phase errors?). And I can make those dips from the SUB+FRONT LEFT better by playing with the distance setting of the FRONT LEFT but then I will lose perfect timing because the IR peaks wil have a delay?

http://www.sendspace.com/file/e78szi


----------



## jtalden

THX-UltraII said:


> I don t think that I have good news. I just measured (.mdat link on bottom of this reply)
> 
> Graph 1: subwoofer (4.25m) +front left (6.12m)
> Graph 2: subwoofer (4.25m) +front right (6.25m)
> Graph 3: no sub, front left (6.12m)
> Graph 4: no sub, front right (6.25m)
> 
> Am I correct that I can make the conclusion that the SPL overlay of the SUB+FRONT LEFT is by far not as good as the SUB+FRONT RIGHT measurement? Can I also make the conclusion (please correct me if I m wrong) that with this setup (distances settings) in a stereo setup the time that the sound arrives at my LP is perfectly balanced between the LEFT and RIGHT signal (that s why I matched the IR peak as good as possible) but the SPL in the SUB+LEFT FRONT has some dips (phase errors?). And I can make those dips from the SUB+FRONT LEFT better by playing with the distance setting of the FRONT LEFT but then I will lose perfect timing because the IR peaks wil have a delay?
> 
> http://www.sendspace.com/file/e78szi


The FR and FL timing is now ideal for that LP.

I checked out the phase alignment between the SW and FR vs FL. They are both aligned as well as possible. 

SPL difference between FL and FR is to be expected. I think you are overly concerned with the difference you found. The SPL differences here look to be relatively minor and very manageable. The more symmetrical the room setup the more similar the SPL response will be. 

I would suggest you retain this alignment and proceed to align the CC, SL, and SL in the same way. When you have all the distances settings established, please post them.


----------



## THX-UltraII

Ok, I ll start measuring the center, surround left and surround right today with the front right IR as 'reference'. The only thing I m still a bit confused about is how to actually do this. My Marantz SR5005 has no MONO MODE. I use my Marantz SR5005 as processor and I use a separate 5-channel power amplifier (NuForce MCH-2-C5) that is connected unbalanced (rca) to the pre-outputs of the SR5005.

I found this in the Marantz SR5005 manual:

http://www.manualowl.com/m/Marantz/SR5005/Manual/222916?page=32

If you read the 'Multi Channel Playback' chapter at page 29 you see there is a option MULTI CH STEREO. Is this the one I should use? (while only playing the channel that I m measuring and disconnect the rest of the channels?)


----------



## THX-UltraII

jtalden said:


> I checked out the phase alignment between the SW and FR vs FL. They are both aligned as well as possible


And how did you do this? (So I can also do it myself)


----------



## jtalden

THX-UltraII said:


> Ok, I ll start measuring the center, surround left and surround right today with the front right IR as 'reference'. The only thing I m still a bit confused about is how to actually do this. My Marantz SR5005 has no MONO MODE. I use my Marantz SR5005 as processor and I use a separate 5-channel power amplifier (NuForce MCH-2-C5) that is connected unbalanced (rca) to the pre-outputs of the SR5005.
> 
> I found this in the Marantz SR5005 manual:
> 
> http://www.manualowl.com/m/Marantz/SR5005/Manual/222916?page=32
> 
> If you read the 'Multi Channel Playback' chapter at page 29 you see there is a option MULTI CH STEREO. Is this the one I should use? (while only playing the channel that I m measuring and disconnect the rest of the channels?)


That setup makes it relatively easy: 
[For this process I will assume that we have just finished the timing adjustment with SW+FR (our reference channel) and are ready to align all the other channels to the FR IR. We still have the mic at the LP and a measurement in REW of the SW and the FR.]

> Leave all speaker wires in place for this entire process.
> Leave the REW output connection to the AVR FR input for this entire process.
> Turn system off (or just the P-amp) then disconnect all 5 RCA connections at the P-Amp. 
> Connect the FR Pre-out RCA connector back into the P-Amp FL channel input. Leave all other P-amp main inputs disconnected.
> Turn on the system and set stereo mode. 
> Turn the SW off
> Adjust the IR timing of the FL to match the measurement of the FR IR per the previous instructions.
> Turn the SW on and measure the SW+FL
> Repeat for CC, SL and SR.
> Save this REW file that contains the SW, 5 Mains, and 5 SW+main measurements as our record of the setup.
> Turn off the system and reset all the RCA connectors back to their original P-amp inputs.
> Record all the AVR distance settings and save them.
> Done. 

EDIT: Notice that the distance adjustment will be made to the FR distance setting in the AVR for all 5 channels. This means we need to keep track of each channel distance we establish. When the process in complete the distances we found are loaded into the AVR for each of the respective channels.


----------



## THX-UltraII

jtalden said:


> That setup makes it relatively easy:
> [For this process I will assume that we have just finished the timing adjustment with SW+FR (our reference channel) and are ready to align all the other channels to the FR IR. We still have the mic at the LP and a measurement in REW of the SW and the FR.]
> 
> > Leave all speaker wires in place for this entire process.
> > Leave the REW output connection to the AVR FR input for this entire process.
> > Turn system off (or just the P-amp) then disconnect all 5 RCA connections at the P-Amp.
> > Connect the FR Pre-out RCA connector back into the P-Amp FL channel input. Leave all other P-amp main inputs disconnected.
> > Turn on the system and set stereo mode.
> > Turn the SW off
> > Adjust the IR timing of the FL to match the measurement of the FR IR per the previous instructions.
> > Turn the SW on and measure the SW+FL
> > Repeat for CC, SL and SR.
> > Save this REW file that contains the SW, 5 Mains, and 5 SW+main measurements as our record of the setup.
> > Turn off the system and reset all the RCA connectors back to their original P-amp inputs.
> > Record all the AVR distance settings and save them.
> > Done.



Juet to be sure:

So for center I plug the FR pre-out in the CENTER in of the amplifier (NuForce MCH-2-C5), for the SR the FR pre-out in the SURROUND RIGHT in of the amplifier and for the the SL the FR pre-out in the SURROUND LEFT in of the amplifier.

I ve just read something about ASIO4ALL in this thread: 
http://www.hometheatershack.com/forums/rew-forum/54840-any-way-generate-sound-center-surrounds.html
Isn t this the way to do it? And how are we going to make a measurement with all 6 channels (5.1) generating sound so see if there are no other problems like cancellation or something like that?


----------



## jtalden

THX-UltraII said:


> And how did you do this? (So I can also do it myself)


I suggest you don't add unnecessary confusion into this. There is no good reason to do that. 

Here is the link to thread containing the process however.

http://www.hometheatershack.com/forums/rew-forum/38617-aligning-driver-phase-rew-v5-example.html


----------



## jtalden

THX-UltraII said:


> Juet to be sure:
> 
> So for center I plug the FR pre-out in the CENTER in of the amplifier (NuForce MCH-2-C5), for the SR the FR pre-out in the SURROUND RIGHT in of the amplifier and for the the SL the FR pre-out in the SURROUND LEFT in of the amplifier.


Yes.



> I ve just read something about ASIO4ALL in this thread:
> http://www.hometheatershack.com/forums/rew-forum/54840-any-way-generate-sound-center-surrounds.html
> 
> Isn t this the way to do it?


If you have the equipment, capability and desire then yes. 

There are several ways. Pick one.



> And how are we going to make a measurement with all 6 channels (5.1) generating sound so see if there are no other problems like cancellation or something like that?


There is no need for that. We are interested in the sound from each main arriving at the LP on time and reproducing that channel accurately. If the signal is unique there will be no interference. If the signal is shared on 2 or more channels then there is no practical way to prevent comb filtering at high frequencies. At low frequencies we only have one speaker. 

That doesn't mean you can't measure them all together just to see what happens if you like.


----------



## THX-UltraII

John,

It s not working. When I always use the RIGHT PRE-OUT of my amplifier and adjust eg. the LEFT DISTANCE nothing happens (of course, because adjusting the LEFT DISTANCE affects the LEFT PRE-OUT and not the RIGHT PRE-OUT)


----------



## jtalden

Sorry - reread post 184. I edited it yesterday to clarify an important point that I forgot to include in the original positing.


----------



## THX-UltraII

How does this look like John?

http://www.sendspace.com/file/rmat34

If this looks goods, what s my next homework I need to do? You told me already in a thread before but maybe you can repost so I m sure what to do tonight (can make measurements in 4 hours again)


----------



## jtalden

THX-UltraII said:


> How does this look like John?
> 
> http://www.sendspace.com/file/rmat34
> 
> If this looks goods, what s my next homework I need to do? You told me already in a thread before but maybe you can repost so I m sure what to do tonight (can make measurements in 4 hours again)


That looks good.

> The SW+FR timing was aligned per “m11”; one of the 3 acceptable targets. 
> The timing (distances) of all the other main speakers was found and recorded and entered in the AVR.
> The SPL and phase of the SW+FL was also confirmed to be acceptable.

With this you can now EQ the system.

Other thoughts:
> The m11 alignment was the target alignment with the most GD as you pointed out several post back. I had mentioned that m12 may provide a preferable sound. It will reduce the GD and still provide approximately the same SPL response in the XO range. The good news is that you can evaluate both pretty easily. 

To convert from m11 to m12 we can use one of the 2 methods below:
1. Subtract 5.16 m from all 5 of the main speaker distances (the SW stays at the current 4.25m).
[With the current mains settings we can’t do this as it results in a negative distance for the SL and SR. The AVR may also have a minimum allowable distance setting to deal with.]
Or,
2. Add 5.16 m to the SW (the mains all stay at their current settings).
[With the current SW setting we may not be able to do this either if we run into a maximum distance that the AVR allows.]

-------------

We know it is the relative distances between speakers that is important so may be able adjust all the distances to fall within the AVR limitations and allow us to adjust between m11 and m12 alignments just by changing only the SW distance.

Assuming the AVR minimum distance allowed is 0.50 m and maximum is 8.00 m, here is one set of numbers that would work:
SW: 4.25 – 3.25 = 1.00 m
FR: 6.25 – 3.25 = 3.00 m
FL: 5.99 – 3.25 = 2.74 m
CC: 5.89 – 3.25 = 2.64 m
SL: 4.91 – 3.25 = 1.66 m
SR: 5.02 – 3.25 = 1.77 m

These distances still provide the same “m11” alignment you have now, but if we want to switch to m12 alignment we just set the SW distance to 6.14 m (1.00 m + 5.17 m). In this way we can switch back as forth with only this SW distance change. 

----------

Regarding EQ:
Since the SPL of XO range is reasonable close for either m11 or m12 alignment the EQ settings can be established using either alignment. The EQ settings will then work well for both alignments. 

I also notice that there is a significant peak in the SPL of all main speakers around 100 – 160 Hz. The EQ of the SW using the Behringer will probably not address this issue well, so I suggest first trying to reduce this peak somewhat using the AVR EQ capabilities. If a course adjustment is made in the AVR first, then the EQ of the SW by the Behringer may be more successful. 

With that, you are ready for EQ. If you want EQ help, you may want to start a new thread with all the pertinent system info and baseline measurement restated so the EQ experts here can jump in without having to dig through this one to find baseline info. 

These last points are just a few suggestions to consider.


----------



## THX-UltraII

> The SW+FR timing was aligned per “m11”; one of the 3 acceptable targets.


Can you summarize one last time how we did this?



> The timing (distances) of all the other main speakers was found and recorded and entered in the AVR.


understand. One thing though: Auddysey measured totally different distance settings (Auddysey corresponds with tape measuring, eg. my surround speakers are @2.80m physical distance and audyssey measured 2.85m). Is audyssey THAT bad?



> The SPL and phase of the SW+FL was also confirmed to be acceptable.


SPL I can see but phase is a thing I would still like to learn too how to see this. Can t one just say that the phase is correct because the SPL has the least dips in the CO range?
And another question about this: why don t we check the SPL and phase of the SW+CC, SW+SR and SW+SL? Escpecially the center speaker does a lot during a movie.

With this you can now EQ the system.



> Other thoughts:
> > The m11 alignment was the target alignment with the most GD as you pointed out several post back. I had mentioned that m12 may provide a preferable sound. It will reduce the GD and still provide approximately the same SPL response in the XO range. The good news is that you can evaluate both pretty easily.


what was a reduced GD again? 



> To convert from m11 to m12 we can use one of the 2 methods below:
> 1. Subtract 5.16 m from all 5 of the main speaker distances (the SW stays at the current 4.25m).
> [With the current mains settings we can’t do this as it results in a negative distance for the SL and SR. The AVR may also have a minimum allowable distance setting to deal with.]
> Or,
> 2. Add 5.16 m to the SW (the mains all stay at their current settings).
> [With the current SW setting we may not be able to do this either if we run into a maximum distance that the AVR allows.]


just checked my AVR. 9.41m (4.25+5.16) is possible with my AVR. 



> We know it is the relative distances between speakers that is important so may be able adjust all the distances to fall within the AVR limitations and allow us to adjust between m11 and m12 alignments just by changing only the SW distance.
> 
> Assuming the AVR minimum distance allowed is 0.50 m and maximum is 8.00 m, here is one set of numbers that would work:
> SW: 4.25 – 3.25 = 1.00 m
> FR: 6.25 – 3.25 = 3.00 m
> FL: 5.99 – 3.25 = 2.74 m
> CC: 5.89 – 3.25 = 2.64 m
> SL: 4.91 – 3.25 = 1.66 m
> SR: 5.02 – 3.25 = 1.77 m
> 
> These distances still provide the same “m11” alignment you have now, but if we want to switch to m12 alignment we just set the SW distance to 6.14 m (1.00 m + 5.17 m). In this way we can switch back as forth with only this SW distance change.


understand this but maybe the subwoofer distance @9.41m is good to go



> Regarding EQ:
> Since the SPL of XO range is reasonable close for either m11 or m12 alignment the EQ settings can be established using either alignment. The EQ settings will then work well for both alignments.


understand



> I also notice that there is a significant peak in the SPL of all main speakers around 100 – 160 Hz. The EQ of the SW using the Behringer will probably not address this issue well, so I suggest first trying to reduce this peak somewhat using the AVR EQ capabilities. If a course adjustment is made in the AVR first, then the EQ of the SW by the Behringer may be more successful.


 understand. My AVR lets me EQ all speakers (not the subwoofer though, but that s the Behringer for right?) separate. Shall I try to EQ all speakers (FR, FL, CC, SR and SL) so they all have a good SPL response? My AVR lets me do per speaker:
-20 to +6 (0 default) for 63Hz, 125Hz, 250Hz, 500Hz, 1000Hz, 2000Hz, 4000Hz, 8000Hz and 16000Hz. And if I EQ them all (separate), are there 'rules' to keep in mind? I remember from my Velodyne SMS-1 subwoofer eq I had a few years ago that increasing (+) was an abslote no-go and that only a few minor decreases (-) at some peaks was recommended. How will that be with my AVR?
And also: will adjusting EQ in my AVR affect delays (timings) that we fine-tuned?



> With that, you are ready for EQ. If you want EQ help, you may want to start a new thread with all the pertinent system info and baseline measurement restated so the EQ experts here can jump in without having to dig through this one to find baseline info.


amost there! (I hope )



> These last points are just a few suggestions to consider


your help is so much appreciated John.


----------



## jtalden

THX-UltraII said:


> Can you summarize one last time how we did this?


Manual “SPL/IR” SW+Main timing alignment method:
[An alternative method to the “SPL/RTA” SW+main timing alignment method.]

Setup steps:
> Mic at LP.
> Choose to use either the FL or FR to establish the timing alignment with the SW. We chose the FR.
> Measure and record the physical distances from the LP of both the SW and FR. Set one of them to 5 m in the AVR and the other to the difference in physical distance. Example: SW measures about 2.8 m and the FR about 3.2 m. So we could add 1.8 m to both values and enter SW = 4.6 m and FR = 5.0 m in the AVR. We will adjust the one that is set to 5 m. In this example that is the FR.
> Previously entered EQ settings can be either left on or turned off.
> Activate Loopback feature in REW.
> Set REW preferences to use 1/3 or 1/6 smoothing.
> Use only full range sweep measurements (15 – 20k Hz) for all measurements. 
> Choose the AVR distance increments to be used for the trial and error process. I recommend about 0.5 m.

Process:
[Trial and error method. (See post 140 for a calculation method.)]
> Sweep measure SW, FR, SW+FR
> View IR locations of the SW and FR initial peaks. [If the initial distances are entered properly the initial rise of the FR and SW IR peaks should fall within 1 or 2 ms of each other. This is good enough for the starting point of this process.] 
> Be sure to label the distance setting on each measurement
> View the overlay SPL graph for the SW, FR and SW+FR. Identify the XO freq range as the range between where either the SW or the FR SPL falls more than maybe 20 or 25 dB from the average SPL in the area adjoining that range. 
> Increment the FR distance and measure both FR and SW+FR. 
> View the overlay SPL graph for each SW+FR measurement. Look to identify a setting that is nearest to the initial starting setting of 5 m that provides the highest SPL through the XO range. [I like to leave the “SW” and “FR at 5.00 m” traces visible also as I review the SW+FR increments because that better shows the SPL fill in the XO range of the traces. A good alignment will have the SPL+FR trace fall as high as possible over the SW or FR trace at all points in the XO range.] 
> After we find that good alignment we can then optionally fine tune that setting by using smaller distance increments. The difference in distance between the SW and FR is the magic number we need to later set the distances in the AVR.
> The setting with the initial rise of SW and FR IRs falling closest to each other is the alignment that provides the closest phase match of the SW and FR throughout the entire XO range.
> Once we find this first solution we can predict the approximate location of alternate solutions. Another solution will fall the distance of one WL (wavelength) greater and another one WL less.
[For example if we find that a solution with the FR at 4.85 m and the XO is at 80 Hz then another solution will be found with the FR near 4.85 + 4.30 = 9.05 m and also one at 4.85 – 4.3 = 
0.55 m (4.3 m being the approx. WL of 80 Hz).] 
If we invert the polarity of the SW, we can expect to find solutions at about 1/2 WL more and 1/2 WL less.
> We are only interested in 3 of the alignments the one that places the initial IR rise of the SW and FR closest to the same time and the ones 1/2 WL above and 12 WL below that. We can go find those alignments and fine tune them if we want. [The distance offsets are only estimates as the actual phase timing may not actually be right at 80 Hz XO freq as was the case here for Sanders setup. To maximize the SPL fill-in in this case the alignment target was nearer 65 Hz than 80 Hz. The offsets distances are thus impacted according, WL distance for 65 Hz is about 5.16 m]
> We should also confirm that this solution works well for the FL speaker as well. 
[I would think it would in most cases, but with my very asymmetrical room setup I decided to use a compromised solution falling between the best solutions found for the FR and for the FL.] 
> We now use any FR and SW distance values in the AVR that retains the offset distance between them. We just need to select values that will provide enough room to allow us to set the CC, SL and SR distances to the values needed. Those that match the same IR arrival time as the FR IR.




> One thing though: Auddysey measured totally different distance settings (Auddysey corresponds with tape measuring, eg. my surround speakers are @2.80m physical distance and audyssey measured 2.85m). Is audyssey THAT bad?


Most comments I see indicate that Audyssey does very well in aligning the SW to Mains. I have not seen measurements (other than my own experiments) that do a good job of comparing the Audyssey results to a well aligned manual setup. My own experience with Audyssey timing is not good, but I have mostly tested it with non-standard setups. If I set my DCX filters to simulate the standard main speaker roll off rates at about 80 Hz then Audyssey did in fact find a good XO setting and good timing. It still boosted my SWs excessively (about +9 dB at 20 Hz; their lower limit). Maybe like many automated setup systems (for any type of system) as long as the expected conditions are found the setup will be acceptable?? Speaker designs and room responses vary so much it is probably difficult to get it right in all cases. 

Your 0.05 m difference for the surrounds is insignificant. The initial timing of your FR was much worse however. I think that is what started the initial concern. 

I speculate that, had you just reversed the polarity on the SW (or all the main speakers) then Audyssey may well have gotten it right. I say that because your initial alignment was close to correct if the polarity of the SW was switched. The IRs were aligned well, but it was about 160 deg out of phase alignment leaving a big dip in your SPL response.



> SPL I can see but phase is a thing I would still like to learn too how to see this. Can t one just say that the phase is correct because the SPL has the least dips in the CO range?


Yes.



> why don t we check the SPL and phase of the SW+CC, SW+SR and SW+SL? Escpecially the center speaker does a lot during a movie.


I think that in movies the CC is primarily a dialog channel and there is little if any bass in it? You can test this with the REW RTA if you like. Maybe someone else here already knows. Even if it does contain bass would you decide to prioritize the timing for the CC at the expense of the FL and FR? 
Your particular speakers are designed to properly to go together in an HT setup. The CC and surround designs are both complimentary to the FL/FR so that the phase timing would be expect to be very similar. I did indeed check this out and, as expected, the phase timing of all 5 speakers is similar so no worries.



> what was a reduced GD again?


I was referring to adjusting the timing such that the GD (Group Delay) of the mid bass (maybe 40 – 65 Hz) would be minimized with the tradeoff being that the phase tracking at the extremes of the XO range is somewhat less than ideal. The phase and GD near the XO will still be the same however.



> just checked my AVR. 9.41m (4.25+5.16) is possible with my AVR.
> 
> maybe the subwoofer distance @9.41m is good to go


Yes, that works fine.



> My AVR lets me EQ all speakers (not the subwoofer though, but that s the Behringer for right?)
> 
> Shall I try to EQ all speakers (FR, FL, CC, SR and SL) so they all have a good SPL response? My AVR lets me do per speaker:
> -20 to +6 (0 default) for 63Hz, 125Hz, 250Hz, 500Hz, 1000Hz, 2000Hz, 4000Hz, 8000Hz and 16000Hz. And if I EQ them all (separate), are there 'rules' to keep in mind? I remember from my Velodyne SMS-1 subwoofer eq I had a few years ago that increasing (+) was an abslote no-go and that only a few minor decreases (-) at some peaks was recommended. How will that be with my AVR?


I’ll let someone else help you with EQ questions. You might want look through the sticky threads and do some general searches on the topic. There is lots of EQ related info available including regarding the boost vs cut situation. You should be able to easily find info on these kinds of basic questions and read through them before you get started.



> will adjusting EQ in my AVR affect delays (timings) that we fine-tuned?


Not significantly.


----------



## THX-UltraII

> Manual “SPL/IR” SW+Main timing alignment method:
> [An alternative method to the “SPL/RTA” SW+main timing alignment method.]
> 
> Setup steps:
> > Mic at LP.
> > Choose to use either the FL or FR to establish the timing alignment with the SW. We chose the FR.
> > Measure and record the physical distances from the LP of both the SW and FR. Set one of them to 5 m in the AVR and the other to the difference in physical distance. Example: SW measures about 2.8 m and the FR about 3.2 m. So we could add 1.8 m to both values and enter SW = 4.6 m and FR = 5.0 m in the AVR. We will adjust the one that is set to 5 m. In this example that is the FR.
> > Previously entered EQ settings can be either left on or turned off.
> > Activate Loopback feature in REW.
> > Set REW preferences to use 1/3 or 1/6 smoothing.
> > Use only full range sweep measurements (15 – 20k Hz) for all measurements.
> > Choose the AVR distance increments to be used for the trial and error process. I recommend about 0.5 m.
> 
> Process:
> [Trial and error method. (See post 140 for a calculation method.)]
> > Sweep measure SW, FR, SW+FR
> > View IR locations of the SW and FR initial peaks. [If the initial distances are entered properly the initial rise of the FR and SW IR peaks should fall within 1 or 2 ms of each other. This is good enough for the starting point of this process.]
> > Be sure to label the distance setting on each measurement
> > View the overlay SPL graph for the SW, FR and SW+FR. Identify the XO freq range as the range between where either the SW or the FR SPL falls more than maybe 20 or 25 dB from the average SPL in the area adjoining that range.
> > Increment the FR distance and measure both FR and SW+FR.
> > View the overlay SPL graph for each SW+FR measurement. Look to identify a setting that is nearest to the initial starting setting of 5 m that provides the highest SPL through the XO range. [I like to leave the “SW” and “FR at 5.00 m” traces visible also as I review the SW+FR increments because that better shows the SPL fill in the XO range of the traces. A good alignment will have the SPL+FR trace fall as high as possible over the SW or FR trace at all points in the XO range.]
> > After we find that good alignment we can then optionally fine tune that setting by using smaller distance increments. The difference in distance between the SW and FR is the magic number we need to later set the distances in the AVR.
> > The setting with the initial rise of SW and FR IRs falling closest to each other is the alignment that provides the closest phase match of the SW and FR throughout the entire XO range.
> > Once we find this first solution we can predict the approximate location of alternate solutions. Another solution will fall the distance of one WL (wavelength) greater and another one WL less.
> [For example if we find that a solution with the FR at 4.85 m and the XO is at 80 Hz then another solution will be found with the FR near 4.85 + 4.30 = 9.05 m and also one at 4.85 – 4.3 =
> 0.55 m (4.3 m being the approx. WL of 80 Hz).]
> If we invert the polarity of the SW, we can expect to find solutions at about 1/2 WL more and 1/2 WL less.
> > We are only interested in 3 of the alignments the one that places the initial IR rise of the SW and FR closest to the same time and the ones 1/2 WL above and 12 WL below that. We can go find those alignments and fine tune them if we want. [The distance offsets are only estimates as the actual phase timing may not actually be right at 80 Hz XO freq as was the case here for Sanders setup. To maximize the SPL fill-in in this case the alignment target was nearer 65 Hz than 80 Hz. The offsets distances are thus impacted according, WL distance for 65 Hz is about 5.16 m]
> > We should also confirm that this solution works well for the FL speaker as well.
> [I would think it would in most cases, but with my very asymmetrical room setup I decided to use a compromised solution falling between the best solutions found for the FR and for the FL.]
> > We now use any FR and SW distance values in the AVR that retains the offset distance between them. We just need to select values that will provide enough room to allow us to set the CC, SL and SR distances to the values needed. Those that match the same IR arrival time as the FR IR.


understand. Maybe a moderator can make a sticky of this information so other members can benefit from your knowledge too.



> Most comments I see indicate that Audyssey does very well in aligning the SW to Mains. I have not seen measurements (other than my own experiments) that do a good job of comparing the Audyssey results to a well aligned manual setup. My own experience with Audyssey timing is not good, but I have mostly tested it with non-standard setups. If I set my DCX filters to simulate the standard main speaker roll off rates at about 80 Hz then Audyssey did in fact find a good XO setting and good timing. It still boosted my SWs excessively (about +9 dB at 20 Hz; their lower limit). Maybe like many automated setup systems (for any type of system) as long as the expected conditions are found the setup will be acceptable?? Speaker designs and room responses vary so much it is probably difficult to get it right in all cases.
> 
> Your 0.05 m difference for the surrounds is insignificant. The initial timing of your FR was much worse however. I think that is what started the initial concern.
> 
> I speculate that, had you just reversed the polarity on the SW (or all the main speakers) then Audyssey may well have gotten it right. I say that because your initial alignment was close to correct if the polarity of the SW was switched. The IRs were aligned well, but it was about 160 deg out of phase alignment leaving a big dip in your SPL response.


I understand all of this. But I just run Audyssey again (of course wrote down all settings we made) and Audyssey says (approx):
FR,CC and FL 5.00m and [email protected] 2.50m (which corresponds with the actual physical distance of my setup). 
The distances we found (for correct time alignment) are approx. 6m for frontstage and 5 meter for surrounds. This is a difference of approx. 1 meter while audyssey measures a difference between front and backstage of 2.5meter......


> I think that in movies the CC is primarily a dialog channel and there is little if any bass in it? You can test this with the REW RTA if you like. Maybe someone else here already knows. Even if it does contain bass would you decide to prioritize the timing for the CC at the expense of the FL and FR?
> Your particular speakers are designed to properly to go together in an HT setup. The CC and surround designs are both complimentary to the FL/FR so that the phase timing would be expect to be very similar. I did indeed check this out and, as expected, the phase timing of all 5 speakers is similar so no worries.


understand



> I was referring to adjusting the timing such that the GD (Group Delay) of the mid bass (maybe 40 – 65 Hz) would be minimized with the tradeoff being that the phase tracking at the extremes of the XO range is somewhat less than ideal. The phase and GD near the XO will still be the same however.


ok, understand



> I’ll let someone else help you with EQ questions. You might want look through the sticky threads and do some general searches on the topic. There is lots of EQ related info available including regarding the boost vs cut situation. You should be able to easily find info on these kinds of basic questions and read through them before you get started.


ok. But one last question about this: is it a idea to let my AVR do the EQ and after this change all settings back to the settings we made except for the dequalization that audyssey did? Or does this affect our settings? (I remember you told something about audyssey a week ago and how it affects things)


----------



## jtalden

THX-UltraII said:


> is it a idea to let my AVR do the EQ and after this change all settings back to the settings we made except for the dequalization that audyssey did? Or does this affect our settings? (I remember you told something about audyssey a week ago and how it affects things)


Audyssey will allow you to change the XO freqs, but I think that as soon as you change any speaker distance setting it will automatically disable Audyssey. I am not sure on this point, but you can easily test it yourself. If this is correct then you cannot manually align the XO timing and and still use Audyssey for EQ. If I am mistaken then you can do that.


----------



## THX-UltraII

I just did a new Audyssey auto measurement again and I still just don t understand why Audyssey gives so big different results then we do with our manual measurement we did. 

Audyssey measures:
FL: 3.84m
FR: 3.93m
CC: 3.72m
SL: 2.64m
SR: 2.79m
SW: 4.17m

We measured:
FL: 5.99m
FR: 6.25m
CC: 5.89m
SL: 4.91m
SR: 5.02m
SW: 4.25m

I know the distances are relative but they don t 'match' at all. So like I asked before: Is Auddysey THAT wrong?


----------



## jtalden

What are the tape measurements?


----------



## THX-UltraII

FL: 3.84m
FR: 3.94m
CC: 3.70m
SL: 2.64m
SR: 2.67m
SW: 3.60m


----------



## jtalden

Note that if we subtract 2.25 m to the manual distance setting for all the speakers there is no impact on the timing at all. So if we do that we get:









The distances to the mains now fall within +/-0.10 m for all 3 methods. Since the Audyssey mic was not placed exactly where the REW mic was placed and the ends of tape measure are also slightly different that is very excellent agreement. There is no evidence or any reason to assume that Audyssey cannot align the main speaker IRs just as well as we did manually. Similarly they can be aligned well with a tape measure with enough care.

The difference then is just in the SW timing that was targeted. Audyssey established different target timing for the XO handoff between SW and the 5 Mains than we did manually and both differ from the tape measurement.

In our measurements above we have good evidence that any one the 3 timing solutions we found manually is a preferable starting point if we intend to manually EQ.


----------



## THX-UltraII

Completely understand John! Thanks for clarification. 
Auddysey did not set a CO at all because Auddysey set my speakers on LARGE which disables the CO. I already learned before I started this thread that LARGE is a no-go and that speakers always have to be set on SMALL (only when you own 20k B&W 800D's or something similar that can do full 20-20000Hz you can set speakers on LARGE). 

But I think (checked this; will let you see tomorrow, not in my HTroom atm) Auddysey did a pretty good job at equalizing my FR, FL, CC, SR and SL. However, the values that Auddysey set for EQ the channels are not shown in my AVR so I cannot write them down and use them in our manual setup. I ve been trying to manually EQ my FR to begin with this afternoon. Spend almost 4 hours on it but it gives me headaches which is the right thing to do. Am I correct that my goal is to get all 5 speakers have a approx. similar SPL responses? (completely similar is not possible due to the limitations of the EQing in the SR5005. One important thing is that I cannot set a width and cannot change the freq. I want to adjust, it are just a few fixed frequencies that can be EQd).


----------



## THX-UltraII

jtalden said:


> Manual “SPL/IR” SW+Main timing alignment method:
> [An alternative method to the “SPL/RTA” SW+main timing alignment method.]
> 
> Setup steps:
> > Mic at LP.
> > Choose to use either the FL or FR to establish the timing alignment with the SW. We chose the FR.
> > Measure and record the physical distances from the LP of both the SW and FR. Set one of them to 5 m in the AVR and the other to the difference in physical distance. Example: SW measures about 2.8 m and the FR about 3.2 m. So we could add 1.8 m to both values and enter SW = 4.6 m and FR = 5.0 m in the AVR. We will adjust the one that is set to 5 m. In this example that is the FR.
> > Previously entered EQ settings can be either left on or turned off.
> > Activate Loopback feature in REW.
> > Set REW preferences to use 1/3 or 1/6 smoothing.
> > Use only full range sweep measurements (15 – 20k Hz) for all measurements.
> > Choose the AVR distance increments to be used for the trial and error process. I recommend about 0.5 m.
> 
> Process:
> [Trial and error method. (See post 140 for a calculation method.)]
> > Sweep measure SW, FR, SW+FR
> > View IR locations of the SW and FR initial peaks. [If the initial distances are entered properly the initial rise of the FR and SW IR peaks should fall within 1 or 2 ms of each other. This is good enough for the starting point of this process.]
> > Be sure to label the distance setting on each measurement
> > View the overlay SPL graph for the SW, FR and SW+FR. Identify the XO freq range as the range between where either the SW or the FR SPL falls more than maybe 20 or 25 dB from the average SPL in the area adjoining that range.
> > Increment the FR distance and measure both FR and SW+FR.
> > View the overlay SPL graph for each SW+FR measurement. Look to identify a setting that is nearest to the initial starting setting of 5 m that provides the highest SPL through the XO range. [I like to leave the “SW” and “FR at 5.00 m” traces visible also as I review the SW+FR increments because that better shows the SPL fill in the XO range of the traces. A good alignment will have the SPL+FR trace fall as high as possible over the SW or FR trace at all points in the XO range.]
> > After we find that good alignment we can then optionally fine tune that setting by using smaller distance increments. The difference in distance between the SW and FR is the magic number we need to later set the distances in the AVR.
> > The setting with the initial rise of SW and FR IRs falling closest to each other is the alignment that provides the closest phase match of the SW and FR throughout the entire XO range.
> > Once we find this first solution we can predict the approximate location of alternate solutions. Another solution will fall the distance of one WL (wavelength) greater and another one WL less.
> [For example if we find that a solution with the FR at 4.85 m and the XO is at 80 Hz then another solution will be found with the FR near 4.85 + 4.30 = 9.05 m and also one at 4.85 – 4.3 =
> 0.55 m (4.3 m being the approx. WL of 80 Hz).]
> If we invert the polarity of the SW, we can expect to find solutions at about 1/2 WL more and 1/2 WL less.
> > We are only interested in 3 of the alignments the one that places the initial IR rise of the SW and FR closest to the same time and the ones 1/2 WL above and 12 WL below that. We can go find those alignments and fine tune them if we want. [The distance offsets are only estimates as the actual phase timing may not actually be right at 80 Hz XO freq as was the case here for Sanders setup. To maximize the SPL fill-in in this case the alignment target was nearer 65 Hz than 80 Hz. The offsets distances are thus impacted according, WL distance for 65 Hz is about 5.16 m]
> > We should also confirm that this solution works well for the FL speaker as well.
> [I would think it would in most cases, but with my very asymmetrical room setup I decided to use a compromised solution falling between the best solutions found for the FR and for the FL.]
> > We now use any FR and SW distance values in the AVR that retains the offset distance between them. We just need to select values that will provide enough room to allow us to set the CC, SL and SR distances to the values needed. Those that match the same IR arrival time as the FR IR


John, I moved my FR, FL, CC, SR and SL a bit in order to get a better SPL curve without EQ. Despite that I did not move them much I need to run through 'our' process again. The first thing I need to do is the above procedure right? If so, the step-by-step guide 'does not fit'. It must be me doing/thinking wrong here. Let me try to explain:

I understand all your steps untill here:


> > Increment the FR distance and measure both FR and SW+FR.
> > View the overlay SPL graph for each SW+FR measurement. Look to identify a setting that is nearest to the initial starting setting of 5 m that provides the highest SPL through the XO range. [I like to leave the “SW” and “FR at 5.00 m” traces visible also as I review the SW+FR increments because that better shows the SPL fill in the XO range of the traces. A good alignment will have the SPL+FR trace fall as high as possible over the SW or FR trace at all points in the XO range.]


I have set my physical FR at 5.00m. This physical difference between my FR and SW is 0.29m. So I have set my subwoofer distance on 4.71m. 
You say to increment the FR distance but to what and how much? I did not test it yet but I can predict (based on measurements and distance values we set in the past weeks) that I have to increase the FR distance quite a lot in order to achieve the highest (best) possible SPL in the XO range. But if I do this the IR peaks of the FR and SW will not be close to each other at all anymore correct?

Am I thinking wrong here?

ps. I know you already did a lot in providing me information but I think we re almost there John


----------



## jtalden

THX-UltraII said:


> John, I moved my FR, FL, CC, SR and SL a bit in order to get a better SPL curve without EQ. Despite that I did not move them much I need to run through 'our' process again. The first thing I need to do is the above procedure right? If so, the step-by-step guide 'does not fit'. It must be me doing/thinking wrong here. Let me try to explain:
> 
> I understand all your steps untill here:
> 
> I have set my physical FR at 5.00m. This physical difference between my FR and SW is 0.29m. So I have set my subwoofer distance on 4.71m.
> You say to increment the FR distance but to what and how much? I did not test it yet but I can predict (based on measurements and distance values we set in the past weeks) that I have to increase the FR distance quite a lot in order to achieve the highest (best) possible SPL in the XO range. But if I do this the IR peaks of the FR and SW will not be close to each other at all anymore correct?
> 
> Am I thinking wrong here?
> 
> ps. I know you already did a lot in providing me information but I think we re almost there John





You are thinking correctly.

Yes, it is best to confirm the timing after moving the speakers or the LP. 

You must have overlooked the final “Setup Step”:
“> Choose the AVR distance increments to be used for the trial and error process. I recommend about 0.5 m.”

[With the initial IR peaks near each other the GD will be reasonable, but the phase may not be favorable. So start the process with the IR peaks close to each other (the physical distances should acomplish this). Then move increments in either direction until the phase is aligned. The phase is aligned when the SPL fill of the SW+FR chart is maximized in the XO range.]

You can run the entire process as listed. That would actually help to find any problems with the process.

But…

You already know the approximate distance settings.

[You did have to move a significant distance from the starting point and you already know approximately how much so you could just fine tune from there using smaller increments.]


----------



## THX-UltraII

John,

I ve read some more about the phase and found out that it is most important to get a best phase between subwoofer and CC. Can I rerun everything and use the SUB+CC as reference instead of the SUB+FR we used all the time?


----------



## jtalden

Sure, you can use the CC as the reference channel for the SW timing if you like. 

No need to rerun everything if you don't want to. You can just fine tune the current setting. It should be very close to ideal already for the CC. 

If a small adjustment is made it can be done to the SW distance. That way all the other channels are impacted the same way and the mains timing is not effected. You can just measure each main with the SW to assure the SPL response through the XO range is still good. 

If you adjust CC distance instead that is okay also, but it is then necessary adjust all the other mains the same amount to retain the proper mains timing.


----------



## THX-UltraII

I did some more thinking last night John. For a 5.1 setup wouldn t it be best to work like this:

1. 
Measure and set the distances from the FR, FL, CC, SR and SL so all the 5 main speakers have the same IR delay. 
(From this moment DO NOT touch the FR, FL, CC, SR and SL distances anymore!)
2.
Measure all main speakers separate while running the subwoofer and look for the best subwoofer distance per main speaker (highest SPL output in XO range).
3. Compare the best IR distances with the best 'subwoofer phase' distances per speaker.
4. Find a subwoofer distance with all these distances you found to get the best compromise for all 5 main speakers+subwoofer where both the IR and PHASE are good.

You will always have to make compromises but this would result in the 'best/avarage' subwoofer distance setting.


----------



## jtalden

THX-UltraII said:


> I did some more thinking last night John. For a 5.1 setup wouldn t it be best to work like this:
> 
> 1.
> Measure and set the distances from the FR, FL, CC, SR and SL so all the 5 main speakers have the same IR delay.
> (From this moment DO NOT touch the FR, FL, CC, SR and SL distances anymore!)
> 2.
> Measure all main speakers separate while running the subwoofer and look for the best subwoofer distance per main speaker (highest SPL output in XO range).
> 3. Compare the best IR distances with the best 'subwoofer phase' distances per speaker.
> 4. Find a subwoofer distance with all these distances you found to get the best compromise for all 5 main speakers+subwoofer where both the IR and PHASE are good.
> 
> You will always have to make compromises but this would result in the 'best/avarage' subwoofer distance setting.


The functional difference in that procedure is that all 5 speakers are used to find a compromise timing alignment. I had suggested that the FL and FR mains be used for the compromise alignment. You also found a source that indicated it is best to use the CC for the timing alignment. 

My suggestion was based only on my experience as a hobbyist. I have not seen any studies or other opinions on the matter, so value it accordingly.

---------
Some of my logic:
Even when using identical main speakers (like mine), the room modes near the XO can shift the phase of the main speakers greatly in the XO range. In my case the SL/SR are similar and nearly 180 deg different than the FR/CC speakers. The FL is significantly different than both of the other sets (about 80 deg). If I were to compromise between all 5 the result might work okay for the FL, but not for the others. For a while I was aligning per the FR/CC. This left a significant dip in the FL SPL. That still worked reasonably well in my case, but recently I have been setting a compromise setting between the FR/CC and FL. I now feel that works a little better in my setup as the EQ boost needed in the FL is reduced a little. 

When deciding to generalize a recommendation I judged that most people would be better served to compromise between the FL and FR mains as I judge them to be the more important main speakers. I also hope that, with a reasonably symmetrical room setup, their phase results would not be too dissimilar. I was guessing this would be better general advice than the other options. I don’t see any sense in providing any weight to the SL/SR if it means significant compromise to the front mains. Everyone’s situation will be different however and no simple guideline can be considered “best” in all cases.]
-------

I have not seen an entire set of measurements for your particular setup so I don’t know what you are looking at for the other 4 main speakers. It’s very possible an average of all 5 mains will work very well in your case. Anyway, now that you have a good feel for the objectives and tradeoffs, you can easily judge that for yourself.


----------

