# How to start measurements when you have multiple subs



## thsmith (Mar 17, 2008)

REW is working for me now and no more manual measurements, yahooooo!

My room (Living room)as most everyone elses is challenging, 4200cf, 8' to 12' sloping ceiling, hardwood floors, fireplace is 10' wide and 12' high. 6' frech door, all windows have heavy drapes and large opening in back of the room to the right from sitting position.

I have a HSU VTF3-MK3 Turbo in front left corner and HSU MBM-12s behind each main.

When I start my measuring I know I need to remove the mains, should I also turn off the MBMs and focus on just the 3 3 T and then turn off 3 3 T and turn on 1 MBM at a time to find best location for subs ?

3 3 T XO is in set at 55hz
MBMs XO out (50hz-150hz)
AVR (Denon 2808) XO set to 120hz

Thanks


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## thsmith (Mar 17, 2008)

ANyone with past experience doing testing with multiple subs ?

Thanks


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## weverb (Aug 15, 2008)

Mine was done with one Outlaw EX and one MBM-12. Here is one post I did where I compared the three different scenarios.

http://www.hometheatershack.com/forums/rew-forum/12622-rew-noob-3.html#post113906


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## brucek (Apr 11, 2006)

> ANyone with past experience doing testing with multiple subs ?


Your situation is not considered multiple subs. You have a low sub and a couple mid subs. 

It's a very difficult job to properly integrate this arrangement into a set of mains, given the obvious time and phase hurdles that have to be overcome.

I would test each sub individually at first, simply to get an idea of how their position is interacting with the room, but I wouldn't get too crazy about trying to get a perfect response at this stage, because you're going to have to get them to play in concert eventually and they will more than likely not react in your favour.

Your low will have to be average phased with the two mid subs, since they're not co-located. Then the phase of each mid will have to be phased with the mains. Since you have them close to each main (and not beside your couch where it is recommended), then this will work in your favour for phasing. You may want to isolate a measure between a mid and its associated main to set the initial phase of each mid.

brucek


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## thsmith (Mar 17, 2008)

Thanks Weverb, I have been following that thread.

After more thought I think I will raise my AVR XO to max

Then with measure just the 3 3 T on and XO out do a measurement

Then do the same for each MBM

and see where I have overlap and gaps.

Once I get to a happy place I want to read more about applying filters to see the changes, I think that is what you did before buying an BFD.


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## thsmith (Mar 17, 2008)

Thanks Bruce, many things to consider and try. For some reason I always seem to do things the hard way.

I tried the MBM in nearfield and did not like it, most likely the large opening to the right and behind me.

The really cool thing is that REW makes taking measurements so much more accurate, fast and easy as opposed to the way I have been doing it with RS meter, Freq cd and Excel.


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## weverb (Aug 15, 2008)

thsmith said:


> Thanks Weverb, I have been following that thread.
> 
> After more thought I think I will raise my AVR XO to max
> 
> ...


Let me know if I can help. Have you done the typical pink noise/RS meter 75dB calibration of...

1. Main sub to highs.
2. One MBM to highs.
3. Other MBM to highs.
4. Both MBM's to highs.
5. All subs to highs.

One of your previous graphs looked like your 3.3 was playing really low compared to the MBM mid-bass. You are going to have a lot of fun playing. You have different positions to try out, with and without turbo to try, and max output versus max extension to try. :bigsmile: Good luck.


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## weverb (Aug 15, 2008)

thsmith said:


> TAfter more thought I think I will raise my AVR XO to max


I would probably not go past 120Hz. There are are a few on the avsforum that have had good luck/response with this setting.


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## thsmith (Mar 17, 2008)

weverb said:


> Let me know if I can help. Have you done the typical pink noise/RS meter 75dB calibration of...
> 
> 1. Main sub to highs.
> 2. One MBM to highs.
> ...


If you are referring to balancing the subs with the mains using RS SPL meter, yes I have.

The 3 3 T looks low because I have not applied the SPL meter calibration/compensation file yet. Plan to do that tonight.

I will certainly be picking your brain on setting filters to predict what a BFD can do for me.

Thanks again.


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## thsmith (Mar 17, 2008)

Bruce, I see what you mean about the sub and MBMs not playing well together. With all 3 on I have a bad suck out at 50hz but individually they look good in that area.

1st graph with 3 3 T and both MBMs on
2nd graph with just 3 3 T on
3rd graph just MBMs on
4th graph just left MBM on
5th graph just left MBM on


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## thsmith (Mar 17, 2008)

Interesting that with 33T and Left MBM phase set to 180 and Right MBM phase set 0 it looks better.


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## weverb (Aug 15, 2008)

Have you added the correction file yet? Why does your graph stop before 200Hz?


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## weverb (Aug 15, 2008)

Also, how are your MBM's playing down to 15Hz. They should drop like a brick after 50Hz.


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## thsmith (Mar 17, 2008)

agree and why does the 33T play way past 60hz with XO in and set to 60hz ? I remember in one of your post you thought your receivers XO was not working. My case it looks like the AVR, sub and MBMs XO are not working.

Any ideas, could it be a REW or Sound card problem with setup?


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## thsmith (Mar 17, 2008)

weverb said:


> Have you added the correction file yet? Why does your graph stop before 200Hz?


Yes, SPL calibration file was loaded, sweep was from 15hz to 135hz. Since I had the mains disconnected I fegured it made no difference to focus on just that range.

Any issues doing this ?


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## salvasol (Oct 31, 2006)

thsmith said:


> agree and why does the 33T play way past 60hz with XO in and set to 60hz ? I remember in one of your post you thought your receivers XO was not working. My case it looks like the AVR, sub and MBMs XO are not working.
> 
> Any ideas, could it be a REW or Sound card problem with setup?


I just want to share this  thread  ... there's some post that talk about the crossover on the subwoofer and AVR ... they said that crossover is not a brick wall, and that speakers and subs will keep playing beyond the crossover frequency :yes:


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## weverb (Aug 15, 2008)

I agree about the xo not being a brick wall as the frequency increases, but the MBM was design to fall off after 50Hz. It should not continue down to 15Hz. If you look at my post with just the MBM graph (linked to before) you can see how it did not respond after about 40Hz.

The 3.3 looks realistic.

What level are you calibrating to with REW? 75dB?

Taking a note from brucek's advice book, have you tested your sound card calibration file to make sure you get a flat line?


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## weverb (Aug 15, 2008)

Have you tested different placement options with the 3.3 to try and get rid of that dip?


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## thsmith (Mar 17, 2008)

weverb said:


> I agree about the xo not being a brick wall as the frequency increases, but the MBM was design to fall off after 50Hz. It should not continue down to 15Hz. If you look at my post with just the MBM graph (linked to before) you can see how it did not respond after about 40Hz.
> 
> The 3.3 looks realistic.
> 
> ...


Agree with the MBM measurements. Not sure what is going on but will investigate. I was calibrating at 76hz. Below is a graph of loaded calibration files for SPL and Soundcard, dash is Soundcard. I am using the Turtle Beach SMR but no issues with calibration.





weverb said:


> Have you tested different placement options with the 3.3 to try and get rid of that dip?



Not with REW but that will be first order of business this weekend if not sooner.


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## weverb (Aug 15, 2008)

Try a measurement of your loopback cable to test your soundcard cal file, and remove the SPL meter calibration file and uncheck "c weighting". Make sure you are getting as flat a line response as possible. Reference the last graph on my page 6 of my post to see what I mean.


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## thsmith (Mar 17, 2008)

weverb, cleared Soundcard cal, unchecked c weight and cleared spl cal.

Here is a screenshot of the settings page just before soundcard cal and the graph. Looks as it should compared to Brucek's, I have the TB SRM card like brucek.

See anything wrong?

Thanks,


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## weverb (Aug 15, 2008)

Looks good. Now take a measurement of it.


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## thsmith (Mar 17, 2008)

With C weight unchecked and SPL cal still unloaded ?

Thanks for your help !

I can not say enough about the usefulness of REW.


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## brucek (Apr 11, 2006)

> With C weight unchecked and SPL cal still unloaded ?


Yes, it should be a flat line.



> See anything wrong?


No, everything looks good.



> sweep was from 15hz to 135hz


Measure subs with a sweep from 0Hz-200Hz.



> but the MBM was design to fall off after 50Hz. It should not continue down to 15Hz.


The response looks about like I would suspect. It does drop off at the assigned 50Hz. Below that the remaining signal is likely enjoying room gain. There also may be some low frequency noise in the room. I don't see a probelm with the MBM response. Take a near field with the sub in the middle of the room (or outside even better) to get a clearer picture.



> I see what you mean about the sub and MBMs not playing well together


Ever considered an 80Hz crossover and the 3 3 T as your only sub and not use the MBM's. The 3 3 T is certainly capable enough. What is your intension/goal with the MBM's?

You do need to turn down the level of the MBM's in relation to the low sub. They're too high to integrate well with the low sub from the graphs you've posted so far. They're both peaking over 80dB. Turn them down.

As a side note on REW, it's a lot easier to evalute responses of each sub if you adjust the REW cutoff target line to the desired crossover. So, if you are testing the low sub, set the target line at 50Hz or 60Hz (there is no 55Hz) and when testing the MBM set the target at 120Hz. It has no effect (except when creating filters), but it helps you visualize how close you are to the desired target.

brucek


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## weverb (Aug 15, 2008)

brucek said:


> The response looks about like I would suspect. It does drop off at the assigned 50Hz. Below that the remaining signal is likely enjoying room gain. There also may be some low frequency noise in the room. I don't see a probelm with the MBM response. Take a near field with the sub in the middle of the room (or outside even better) to get a clearer picture.


I understand having some room gain, but 70-72dB at 18Hz!?! :huh: Is there a way to test for "low frequency noise in the room"? Can you turn the highs and lows off and run a measurement? Would that show you anything?


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## thsmith (Mar 17, 2008)

Thank Brucek, all input and ideas are welcome and I will try your suggestions.

I am not sure what my intent was with the MBMs now, I think I just started aquiring toys which is not good. I should have apllied science first like learning to use REW. No harm done if I find I do not need them, the used market for MBMs look good.

I like your idea of focusing on the sub and may go back to near field with one of the MBMs if needed and see how REW shows it integrating.

I do have a question for you, I had the 3 3 T and MBMs balanced using this method, any issues with this approach?

Using AVR test tone I matched 3 3 T and MBM
Ref test tone was 80dB and measured one MBM to 78dB, then turned off and did the same for second MBM. With both MBMs on it gave me 80dB.

With both MBMs off I measured the 3 3 T to 80dB with the XO out(normally in).

With the 3 3 T and MBMs on I lowered the AVR sub level to 80dB. Then set 3 3 T XO back to in.


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## brucek (Apr 11, 2006)

> Using AVR test tone I matched 3 3 T and MBM


A poor way to do it if there are peaks in a subs response. There is a difference in energy returned when using band limited pink noise if there are peaks, compared to a sub that has a flat response across that band. Peaks will always upset a simple SPL meter level check. In your case I would use REW as the best way to tweak the levels. I would first use the receiver test tones to set them all equal (subs, mains, etc) and then use REW to tweak the level of the MTM's (down in your case).

brucek


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## brucek (Apr 11, 2006)

> Is there a way to test for "low frequency noise in the room"?


Yes, use the REW Spectrum Analyzer.

Once your levels are setup for a normal response measure, then select the Spectrum tab and the following settings.
Mode = Spectrum, FFT Length = 65536, Averages = 2 or 4, Window = Rectangular, Y Axis = dBFS

Select the Signal Generator and select WhitePN (periodic White Noise).

Press the RED record button on the Spectrum page.

It lets you examine the room for noise energy that you may not be aware of.

Below is a pic of my office with the Spectrum analyzer running with no signal being generated.

You can see my furnace is introducing some low frequency noise. If I shut it off, the noise is eliminated.

You can see I have the typical poor PC computer 60Hz hum and its related harmonics at 120Hz, 180Hz, 220Hz etc. 

You can also see (amazingly), my NTSC RPTV CRT's horizontal oscillator frequency of 15.750Khz present in the room. 

The TV is several rooms away and happened to be turned on, but the oscillator noise is present in my office (not that I can hear it, but there it is). Shut the TV off and it goes away.

The Spectrum analyzer can tell you a lot about your room and system before you even do a measure.

Sometimes you'll see a waterfall with a strange signal that rings out for many hundred of milliseconds. If you looked at the spectrum, you might see the source, rather than incorrectly deciding it comes from a modal resonance.... My furnace is a case in point on that issue.










The RTA is also quite useful in REW for dynamic measurements, rather than a simple static measure.

Below is a response measure and then a quick RTA. Once this is running, I can then move the microphone around to see what different listening positions look like (all in real time). It is revealing to see the difference a few feet make when you move the mic, and to compare against the simple response measure on the screen at the same time for comparison.

The RTA also allows you to change filters or move equipment and watch the RTA screen for the real time changes. It's also really useful to adjust phase on a subwoofer for the best crossover response. You simply watch the RTA screen as you dial the phase control. A lot better than taking a bunch of measures to accomplish this task.

Here's a pic of RTA and a response measurement on the same screen (measurements are selectable to be placed on the RTA screen for comparison). 
I was sure not to move the mic when I took the measure and then started the RTA. 

Pay attention to set the RTA up properly. See the setup values on the plot below. (note that the RTA requires switching the Signal Generator to PinkPN (periodic Pink Noise)













> I understand having some room gain, but 70-72dB at 18Hz!?!


Well it's about 15dB above the noise floor. Remember, if there's a high noise floor (typical 45dBSPL, but can be much higher), then the meter calibration file will raise the signal level as the frequency drops. A response chart signal can be mis-interpreted as actual signal, when it's really just noise being raised by the meter calibration file. Consider an old analog Radio Shack meter is adding +30dB offset at 10Hz from the cal file. A high noise floor will show as signal. This is the case with the MBM plots on page 1 of this thread. See how the signal drops nicely until about 30-35Hz and then begins to rise as the frequency goes lower than that. The signal below the drop is noise......... ignore it.

brucek


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## thsmith (Mar 17, 2008)

WOW BRUCEK, excellent information ! When I was calibrating my SPL before performing a measure test I was seeing 45 or so dB when no one was in the room and no tones being generated. I do think my AC was running (92 degrees hear in Dallas yesterday). Looks like I now have a way to measure the room before taking measurements.

THANK YOU !


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## thsmith (Mar 17, 2008)

Weverb, ok here is the graph with Soundcard calibrated, SPL cal unloaded and c weigh unchecked, then with loop in place measured like I would normally. 

Looks good to me but would appriciate confirmation. 

I think I am done measuring until the weekend, seems I have come down with a cold:sad:


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## thsmith (Mar 17, 2008)

Better graph on soundcard loop measurement.

Looks perfect to me but others may see something I have missed.

next step is to start taking measurements focused on the 3 3 T with AVR xo at 80hz and MBMs turned off.


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## thsmith (Mar 17, 2008)

Thanks weverb for confirming the soundcard calibration.

Soundcard and RS analog cal file loaded and c weight checked.

RS SPL meter at LP set to slow and C weighting.

The graph below represents my starting point. MBMs powered down. HSU VTF3-MK3 turbo off, XO out, balanced with mains and located in left front corner (ceiling height is 8' vs opposing corner with ceiling 12'). AVR XO 80hz, Auddessy off.

I have moved and mesaured the sub within the limits I can move it in front left corner, chart represents best location.

*Any tips on next steps would be great !*


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## brucek (Apr 11, 2006)

> Any tips


I think the sub could be better at the 32Hz dip if you moved it around a bit.

The peaking around 80Hz might be fixed with some phase adjusting of the sub.

Levels look good. Generally looks pretty good..

brucek


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## weverb (Aug 15, 2008)

Take some comparison graphs of the 3.3 in 0 versus 180 phase like brucek mentioned. Also try max extension versus max output mode. I take it, this last graph was with the mains turned on? Keep the turbo off for now. We will add that variable later.


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## thsmith (Mar 17, 2008)

Thanks Bruce. I have added a pic of my room in case that helps.

I will move the sub tomorrow to see if I can tackle the 32hz dip. Unfortunately the sub only has 0 and 180 degree phase adjustments but I will try it as I move the sub.

I also want to put one of the MBMs near field and see if it will integrate. Looks like the only place it might help is the 70hz dip.

Are there other graphs I need to look at that may reveal a need for BFD?


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## thsmith (Mar 17, 2008)

weverb said:


> Take some comparison graphs of the 3.3 in 0 versus 180 phase like brucek mentioned. Also try max extension versus max output mode. I take it, this last graph was with the mains turned on? Keep the turbo off for now. We will add that variable later.


OK, I did try MO, but did not save the measurement, I will re-measure and post tomorrow.

Yes the mains were both on.

Thank you !


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## brucek (Apr 11, 2006)

> Unfortunately the sub only has 0 and 180 degree phase adjustments but I will try it as I move the sub.


You may also use the subwoofer distance setting in the receiver. It is a close proxy for the phase adjustment.



> Are there other graphs I need to look at that may reveal a need for BFD?


Waterfall plots will reveal the time domain. Use the same scaling as response graphs.

brucek


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## thsmith (Mar 17, 2008)

Here are my latest measurements with just the 3 3, no turbo or MBMs. I used different phases combined with AVR distance. Audessy has the sub at 20' but real distance is 14'. I made test on distance focused primarly on these 2 ranges as either side of 14' and 20' had worst results.

Looks like second graph is the best.

1st graph is phase 0 AVR distance 14'
2nd graph phase 0 AVR distance is 20'
3rd graph is phase 180 distance 14'
4th graph is phase 180 distance 20'


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## thsmith (Mar 17, 2008)

Here is a waterfall of phase 0 AVR distance is 20'

Not sure what it is telling me and more importantly what my next steps should be.

brucek or weverb, thought ?

Thanks


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## weverb (Aug 15, 2008)

I would agree on the second also. How does it sound? Are you planning on a BFD? Have you read about making a house curve? Depending on your answers to these questions will help decide what your next steps are.


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## thsmith (Mar 17, 2008)

Sounds ok not as strong as it was before with MBMs. Also I think I screwed up as I had Audessy on during my testing so I need to redo with out it.

Have not gotten to the House curve reading yet, sounds like once I can get back to chart 2 without audessy then that would be next steps.


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## weverb (Aug 15, 2008)

thsmith said:


> Sounds ok not as strong as it was before with MBMs. Also I think I screwed up as I had Audessy on during my testing so I need to redo with out it.
> 
> Have not gotten to the House curve reading yet, sounds like once I can get back to chart 2 without audessy then that would be next steps.


That's what I found too. When the bass is flat with the highs, everything sound FLAT. No depth to the music. You are going to want to start reading the house curve sections next. It sounds complicated, but it is not too bad. It will be the most subjective part. Meaning your ears will be the deciding factor.


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## thsmith (Mar 17, 2008)

Well Audessy is definately helping me in the 33hz dip. Without Audessy I am unable to raise that dip by moving the sub in its corner which I have about 24"s to play with. I am able to raise the 72hz by setting phase to 180 and using the distance as measured from sitting position.

How important is it to take Audessy out of the equation ?


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## weverb (Aug 15, 2008)

thsmith said:


> How important is it to take Audessy out of the equation ?


You can keep it on for now. Even with it, it is clear you could benefit from a BFD. If you choose to pursue a house curve, you will probably be fitting Audessy and will definitely need a BFD.


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## thsmith (Mar 17, 2008)

Weverb, I do not understand. Where and how would I benefit using a BFD, lower my peaks ? It looks like I have a lot to deal with. Should I start setting filters to see how flat I could get without actually having a BFD in order see at least graphically what could be done.

Briefly reading the house curve article it looks like you first need an EQ, is the correct?

Kind of lost in the digital dust or analog dust at this point.

I do know that I have really done nothing except shut down the MBMs, taken off the Turbo and changed the phase on the sub and distance on the receiver.


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## weverb (Aug 15, 2008)

thsmith said:


> Weverb, I do not understand. Where and how would I benefit using a BFD, lower my peaks ? It looks like I have a lot to deal with. Should I start setting filters to see how flat I could get without actually having a BFD in order see at least graphically what could be done.
> 
> Briefly reading the house curve article it looks like you first need an EQ, is the correct?


Yes, a BFD will help tame those peaks and get a smoother response. I would start reading Wayne's very informative section about filters. Make sure you understand the basics and then you can start playing with filters.

A BFD is very important to dialing in a house curve. You can start doing the listening and measuring point now. You will probably have to revisit it after you smooth out your current situation.


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## salvasol (Oct 31, 2006)

thsmith said:


> ... Where and how would I benefit using a BFD, lower my peaks ? It looks like I have a lot to deal with. Should I start setting filters to see how flat I could get without actually having a BFD in order see at least graphically what could be done...


I'm not an expert (I just used REW a couple of times) ... but my suggestion is to use the EQ on your AVR if it has one (I did the same with my Yamaha RXV-2700) :yes:

Your frequency response is not to bad ... try the PEQ first, and then decide if you want/need a FBQ or not :bigsmile:

Also, after you get an acceptable response ... don't forget to integrate the rest of the speakers to see how they will play together :yes:


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## thsmith (Mar 17, 2008)

*Sub graph with filters - Feedback/direction Welcomed*

Not sure I have this right but here goes. SUB only on (HSU 3 3), AVR xo at 80hz and Audessy is on. Without Audessy I have a nasty dip at 35hz. Do not have a BFD yet but simulated using 1124P

REW picked 6 filters. I set max peaks to find at 70hz as I read you do not want to use filters at the XO.

Thanks in advance for feedback and directions.


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## thsmith (Mar 17, 2008)

*Re: Sub graph with filters - Feedback/direction Welcomed*

This time with mains and sub on.


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## thsmith (Mar 17, 2008)

Thanks David, AVR (Denon 2808 does not a sub EQ just the other speakers and goes down to 63HZ. Not sure why having Audessy on helps me at 33hz (just sub or sub and mains). The chart looks better but it the sound has alot less punch. 

I have a new post with just sub and sub and mains letting REW pick the filters.


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## weverb (Aug 15, 2008)

*Re: Sub graph with filters - Feedback/direction Welcomed*

Obviously read the whole thread, but read this section a few times:

http://www.hometheatershack.com/for...els-hard-knee-house-curve-long.html#post55656

I had to read it like three or four times to make sure I had a good grasp of what Wayne was saying. Also, don't be afraid to ask Wayne, brucek, etc for help with the filters. The fewer the better.


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## weverb (Aug 15, 2008)

*Re: Sub graph with filters - Feedback/direction Welcomed*

Just to let you know, you probably could get away with only 2 filters (the first two). :bigsmile:


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## brucek (Apr 11, 2006)

Did you press the Optimize PK Gain & Q button when you created those filters - it doesn't look as though you did?

brucek

P.S. I merged your threads


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## thsmith (Mar 17, 2008)

Thanks Brucek, I thought I had but afer re-reading http://www.hometheatershack.com/foru...html#post55656
things look a lot different as weverb had predicted.

Probably being hasty but I am going to go ahead and pick up a 1124P.

Thanks again


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## weverb (Aug 15, 2008)

You can now start reading about house curves. Let's get those MBM's back! :bigsmile:


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## thsmith (Mar 17, 2008)

weverb said:


> You can now start reading about house curves. Let's get those MBM's back! :bigsmile:


Yep that is in the plans. I did pick up a 1124P yesterday but did not have time to pick up the right connectors and cables, will do that today.

I think first I will focus on just the 3 3 going through the entire process using filters then load a house curve and once I get to a happy place then start to integrate the MBM or MBMs.

Seems integrating the 1124P should not be too tough, famous last words. 

Was kind of surprised that once I have the input level on the BFD setup that to balance the sub and mains I will have to use the sub amp which will make balancing the sub and MBMs more challenging.

Hopefully next post will have some correct measurements and graphs leading up to the house curve which should be the next steps.


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## thsmith (Mar 17, 2008)

BFD 1124P is now integrated with system. 

First graph is measurement with using auto filter instructions. Rew identified 2 filters.
Second graph is measurement with both filters applied to BFD no smoothing.
3rd graph is measurement with both filters applied to BFD 1/3 smoothing.

Looks good to me and I can see where the filters have reduced the peaks as intended.

Looks like next steps are to set up a house curve. WHen setting up the house curve will it get set as a 3rd filter ?

Thanks,


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## weverb (Aug 15, 2008)

thsmith said:


> BFD 1124P is now integrated with system.
> 
> First graph is measurement with using auto filter instructions. Rew identified 2 filters.
> Second graph is measurement with both filters applied to BFD no smoothing.
> ...


Do not use smoothing for sub graphs. Looks great otherwise. You may be able to do something about that dip after 70Hz. Don't know where your xo is set though or how thing look with your mains on. No, a house curve is not a 3rd filter. You will probably create a few new filters once you develop a house curve. They can be saved to a different memory setting in the BFD. I have two saved on mine. One has Wayne's hard knee house curve settings and the other has one with a little more mid-bass, but still a 6dB house curve.


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## thsmith (Mar 17, 2008)

kewl weverb. Graphs were with just the sub and the xo is 80hz. 

Just trying to feel more confident about REW and what I am doing so keeping it simple.

Thanks for the feedback and confirmation. I will start working on the 70hz and see how it looks with mains on.


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## thsmith (Mar 17, 2008)

This time with mains on. Same 2 filters applied. House curve reading next.


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## weverb (Aug 15, 2008)

Looks good.


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## thsmith (Mar 17, 2008)

I have setup a house curve just as a test sample as seen in the graph below.

Where I am lost is what to do next, I have read Waynes House curve article several times but just don't get the next step.

I have my 2 filters loaded to make my bass flat. 

Suggestions very much appriciated.


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## weverb (Aug 15, 2008)

Turn up the dial on the back of the 3.3 to get the 15-30Hz section to straddle the target line like your graph does in post #60. Then create new filters to bring down the rest of the response to the new target line. Save these settings to a different memory position. Redo the steps for measuring for a house curve to verify they "sound" the same volume. Play some of your familiar reference material (music, movies, etc.) and see how it sounds.


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## thsmith (Mar 17, 2008)

AH-HA ! 2 more questions for clarification. 

Turn up the dial on the back of the 3.3 to get the 15-30Hz section to straddle the target line like your graph does in post #60. *Am I still using the previously created filters in the BFD ?*
Then create new filters to bring down the rest of the response to the new target line. 
*Will the previous 2 filters need to added in manually or they irrelevant at this point?*

Was the whole point of getting the bass response flat using the 2 filters to just see if it is possible then at the point you set the House curve and create a whole new set of filters?


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## weverb (Aug 15, 2008)

thsmith said:


> AH-HA ! 2 more questions for clarification.
> 
> Turn up the dial on the back of the 3.3 to get the 15-30Hz section to straddle the target line like your graph does in post #60. *Am I still using the previously created filters in the BFD ?*
> Then create new filters to bring down the rest of the response to the new target line.
> ...


The point of getting it flat was to make everything measure the same so that it would be easier to calculate how much of a dB slope you would need to make them "sound" the same.

I would save/copy the setting you have in post #60 to another memory setting (say #9). I would temporarily bypass the BFD and then turn up the 3.3 until the 15-30Hz section straddles the target line. Once that is dialed in, repeat the steps you did to create the original 2 filters. You may only have to turn down the gain on the two you already have, or you may need to create three new ones.


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## thsmith (Mar 17, 2008)

:hail:Thanks weverb, I think it is starting to sink in. Again thank you for your support and patience.

Can wait to get home tonight !


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## weverb (Aug 15, 2008)

Also don't forget to change your graph axis to the standard of:

Vertical = 45dB-105dB
Horizontal = 15Hz-200hz.

Had to get that in before brucek.


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## thsmith (Mar 17, 2008)

OK, house curve at 30hz 6db, still just 3 3 (no turbo or MBMs). 2 filters but they are very simular to previous filters using normal curve. AVR xo 80hz.

What do you think, am I on or off the track here?:wits-end:


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## weverb (Aug 15, 2008)

Yup, looks like you could still turn the 3.3 up a little more.


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## DrWho (Sep 27, 2006)

You should be using shelf EQ's if you want tone control...


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## thsmith (Mar 17, 2008)

DrWho, can you explain or point me to directions for setting up shelf EQ?


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## weverb (Aug 15, 2008)

The 1124P cannot do shelfing filters. You would need a better eq. for that capability.


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## thsmith (Mar 17, 2008)

Have started to integrate back some stuff. Have Turbo on 3 3 now with XO engaged at 45hz, 1 MBM behind Right main (3 3 is on left side of room), AVR XO 120hz. 3 filters on BFD.

Sounds pretty good, after wife wakes up from nap I can really test it out.


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## weverb (Aug 15, 2008)

thsmith said:


> Sounds pretty good, after wife wakes up from nap I can really test it out.


Time for .... :hsd: !


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## thsmith (Mar 17, 2008)

Listened to some Dire Straits, Little River Band, Phoenix, Steely Dan and Super Tramp.

Very nice ! 

I like having just the 3 3 setup and could easily stay that way but I am really liking having one of the MBMs back in.

Movies next.


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## weverb (Aug 15, 2008)

You should also try Eagles "Hell Freezes Over".... Hotel Cali. and Life In The Fast Lane are great! :bigsmile:


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## thsmith (Mar 17, 2008)

EXCELLENT, I have all of those.

I guess I never knew what I was missing, I love the punch and clarity.

Watched Ireon Man on BR lastnight with just the 3 3 and it was amazing. Much better than the theater. My 25 year old son loved it.


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## thsmith (Mar 17, 2008)

I find I like music best with the MBM, 3 3 T xo 45hz and avr 120hz and for movies just 3 3 T xo out and avr xo 80hz.

Many thanks to weverb, brucek, wayne and david for your help, confirmations and support.


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## weverb (Aug 15, 2008)

What are your plans for your second MBM? :bigsmile:


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## thsmith (Mar 17, 2008)

I am going to sell it to a friend of mine who has been looking for a used one.


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## weverb (Aug 15, 2008)

Too bad... :gah: :bigsmile:


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## thsmith (Mar 17, 2008)

Sent you a PM.


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## thsmith (Mar 17, 2008)

I have a couple of follow up questions.

this link has my latest graph and I am now wondering if I did it incorrectly.

http://www.hometheatershack.com/for...when-you-have-multiple-subs-3.html#post119443

I have my 33T XO engaged at 45hz, 1 MBM behind Right main (3 3 is on left side of room), AVR XO 120hz. 3 filters on BFD.

Questions are:

I have my house curve set at 30hz 4 db and 80hz 0 db. Since I have my crossover set on the AVR at 120hz should I have used 120hz at 0 for the house curve ?

On the toolbar Target settings I had Cutoff HZ set at 80hz should it have been set at 120HZ since I had the AVR XO set at 120HZ?

Should I set the values above to 120hz and rerun REW and setting filters accordingly ?

Thanks,


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## weverb (Aug 15, 2008)

I guess the easiest way to check, although it may not be correct, play a sine wave at 120Hz and one at 80Hz and see if they sound the same "volume". If you have to turn up the 80Hz, then move the 0 to 120Hz. I believe you have said that you like the way that it sounds now. I believe that is what is most important.


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## thsmith (Mar 17, 2008)

I do like the way it sounds. IF I change the house cuve to 120hz at 0 and cutoff hz to 120hz againest the referred to measurement file as sort of a simulation it would appear I could raise the volume on the MBM a bit.

I was just curious if I needed to have made the referred to adjustments originally or not.

Tonight I will try it and see how it looks and sounds.

You just have to love REW with its flexibility and real time results.


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## weverb (Aug 15, 2008)

thsmith said:


> Tonight I will try it and see how it looks and sounds.


From a non-expert, I think this is the best approach. :bigsmile:


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## thsmith (Mar 17, 2008)

hey, you are an expert to me :hail::T:bigsmile:


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## JohnM (Apr 11, 2006)

thsmith said:


> I have my house curve set at 30hz 4 db and 80hz 0 db. Since I have my crossover set on the AVR at 120hz should I have used 120hz at 0 for the house curve ?


You start the house curve at the frequency where you find (subjectively) that it sounds better to have a bit more bass. It is not connected to your crossover frequency except that it would not make sense for it to be higher than the crossover.



thsmith said:


> On the toolbar Target settings I had Cutoff HZ set at 80hz should it have been set at 120HZ since I had the AVR XO set at 120HZ?


Yes, but remember that if you are measuring with a main speaker running as well as the sub(s) the target should be set to Full Range, not subwoofer. The subwoofer target is only valid when the mains are off.


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## thsmith (Mar 17, 2008)

Thanks JohnM, that definately changes things. I have been using subwoofer even with mains on.

Looks like I have some work to do which is a good thing.


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## thsmith (Mar 17, 2008)

This graph is with the 33T xo 45hz, MBM nearfield and AVR XO 80hz and with mains on, scan up to 3K hz.

Not sure what to do about the above 80hz dips.


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## weverb (Aug 15, 2008)

thsmith said:


> Not sure what to do about the above 80hz dips.


Have you tried graphing the different results after playing with the two subs phases?


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## thsmith (Mar 17, 2008)

NO but that is excellent idea. I was thinking the same thing after I had disconnected everything and listening to music.

I will give that try this week.


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## weverb (Aug 15, 2008)

Also, it seems to be better to have your target line centered through your response. This will help reduce how much you are cutting/boosting certain frequency ranges. With that, you may be able to turn up the 3.3 a tad more.


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## thsmith (Mar 17, 2008)

In the case of running a sub and a MBM is it possible to use a y cable to feed the sub in from the AVR to both the right and left channels of the BFD so you could use different filters for the sub on say the right channel out of the BFD and left channel out to the MBM ?


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## weverb (Aug 15, 2008)

thsmith said:


> In the case of running a sub and a MBM is it possible to use a y cable to feed the sub in from the AVR to both the right and left channels of the BFD so you could use different filters for the sub on say the right channel out of the BFD and left channel out to the MBM ?


About the only thing you may gain from doing that is an additional 12 filters. I have both my main sub and MBM fed to the left input only. Then again, I have only had to use 4 filters for both subs.


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## thsmith (Mar 17, 2008)

I have 2 filters on mine but I was wondering if you wanted to you could target specific freqs for specifc subs using this method but what you say makes sence. 

I was discussing this with a friend of mine that has two of the big Outlaws and an MBM. He is considering using this approach but as you say I am not sure of the value in doing this.

Thanks weverb !:T


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## weverb (Aug 15, 2008)

thsmith said:


> I was discussing this with a friend of mine that has two of the big Outlaws and an MBM. He is considering using this approach but as you say I am not sure of the value in doing this.


Lucky friend! :R


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## thsmith (Mar 17, 2008)

Yep and he keeps reminding me :bigsmile:. He just got his BFD so we get to play tomorrow:yes::hsd::scared:


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