# Some guidance please



## BritInVA (Feb 12, 2009)

New to REW......so please go easy on me. :jiggy:

- REW v4.11 b1086
- Toshiba Tecra laptop running Windows XP
- M-Audio Mobile Pre USB Souncard
- Beringer ECM 8000 mic (calibrated)

First after researching I beileve I calibrated soundcard. Loopback from Output 2/R to Input Ch2. After running thru calibration steps I get following.










Which looks like that in help......so far so good

Next I ran the check to see if calibration was succesful but unsure if this is the correct result as its very different to that in help.










Appreciate if someone can confirm before I continue.

Thanks,
In advance.

Cheers,
Mark


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## brucek (Apr 11, 2006)

> Next I ran the check to see if calibration was succesful


I don't see any problem.

You've got the target, soundcard cal and corrected checkboxes selected, so that adds confusion to the graph, but your correct straight blue line is there, as it should be...

You should be using a vertical scale of 45dB-105dB.

brucek


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## BritInVA (Feb 12, 2009)

brucek - Thanks.

Thats part of my confusion. in the help it does not show or say what should or should not be checked.

Onto the next step.


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## brucek (Apr 11, 2006)

> in the help it does not show or say what should or should not be checked.


The checkboxes only effect what is shown on the plot. That's it.

If you want to see it, you check it...

brucek


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## Anthony (Oct 5, 2006)

Yep, looks fine to me.

Bruce and I did a loopback check with a voltage divider to check line-out to mic-in to see if there was a difference. Almost none. Something like 1/4 dB at 20 Hz and spot on for the rest of the spectrum.

So that cal file you did for your MobilePre is probably good enough. You can also enable loop-back on Channel 1 and use a effects cord (1/4" tip-sleeve to do Ch 1/L to Ch 1 Line in). That loop replaces the calibration file and is theoretically more accurate in case anything changes over time (unlikely). But you'll get good results either way.

Happy measuring!


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## BritInVA (Feb 12, 2009)

OK......next

Removed loop and connected Output R/2 to the Aux on my AVR (Denon 2807) using splitter at AVR to L&R.

Connected Mic to Mic Ch2 and turned on Phantom power.

I've run thru checking levels using Speakers - using RS Analod SPL meter set AVR volume so reading was 75db. 

Then calibated SPL Reading also to 75db.

And them made measurement during which got follow message










And following graph










If I change the Sweep Level or AVR volume it says I need to "Set Target Level". Now does that mean I need to take another SPL reading and then change the calibration reading to this value?

Thanks,
Mark


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## salvasol (Oct 31, 2006)

BritInVA said:


> If I change the Sweep Level or AVR volume it says I need to "Set Target Level". Now does that mean I need to take another SPL reading and then change the calibration reading to this value?


I remember reading about a trick ...I think you just increase the volume in the AVR and set the target to 75db (even if your reading on the SPL is higher), then do the check levels first to see if you still get the same message about levels ...if not, do the new reading :yes:


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## BritInVA (Feb 12, 2009)

OK so I found the "Target Settings" panel :duh:

But still unsure what I need to do.


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## salvasol (Oct 31, 2006)

BritInVA said:


> OK so I found the "Target Settings" panel :duh:
> 
> But still unsure what I need to do.


Just set the target to 75db ...then do the check levels and look for an error message, if not , you're set to measure :yes:

P.S.: If you're measuring sub response only, post the graph with this settings: 45db-105db and from 10Hz to 200Hz ...for full frequency the same 45db-105db and from 10Hz to wherever your measuring.


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## BritInVA (Feb 12, 2009)

So to be sure I'm understanding this right.

- Increase volume on AVR
- Set Target level to 75db
- Run Check level to see if error persists


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## salvasol (Oct 31, 2006)

BritInVA said:


> So to be sure I'm understanding this right.
> 
> - Increase volume on AVR
> - Set Target level to 75db
> - Run Check level to see if error persists


Yes.

But before increasing the volume....What target did you have before you found the "Target setting panel"??? ...75db???...maybe you just need to set the correct target and don't need to increase volume :yes:


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## BritInVA (Feb 12, 2009)

Target was already at 75db.

I increased volume on AVR so SPL was 80db.

Rerun measurement and no message and get following.










Now to understand what it all means. :crying:

Appreciate any input on how good or bad this looks and what I should be doing next.

Cheers,
Mark


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## salvasol (Oct 31, 2006)

BritInVA said:


> Now to understand what it all means. :crying:
> 
> Appreciate any input on how good or bad this looks and what I should be doing next.


Couple of suggestions:
1) Use 1/3 smoothing.
2) Change settings 10Hz to 24KHz.
3) Use the save graph icon, I think the standar size is 800x800 (I think is below the graph) :scratchhead:


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## BritInVA (Feb 12, 2009)

Like this?


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## brucek (Apr 11, 2006)

Mark,

It's normal practice to first check your subwoofer alone, and then add the mains to setup your crossover region, then do a full range if you require it. When checking subwoofers, remove the mains, and use the subwoofer test signal. 

*For subwoofers, always use the standard Vertical graph axis of (45dB - 105dB) and the Horizontal graph axis of (15Hz - 200Hz) using the Graph Limits button in the top right corner of REW.

For full range, use the standard Vertical graph axis of (45dB - 105dB) and the Horizontal graph axis of (15Hz - upper limits you desire. i.e 20KHz).*

For full range only, enable smoothing to eliminate the comb filtering. Use a 1/3 octave smoothing.

There is a floppy icon in the bottom left hand corner of the REW screen. Please use it to create your 800 bit wide graphs. You do not need to post the entire REW page.

Be sure you have the microphone calibration file loaded.

brucek


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## BritInVA (Feb 12, 2009)

brucek said:


> It's normal practice to first check your subwoofer alone, and then add the mains to setup your crossover region, then do a full range if you require it. When checking subwoofers, remove the mains, and use the subwoofer test signal.


Bruce, 

Thanks.

1) So do I physically disconnect the mains from the AVR?

2) Do I go into AVR and increase the current crossover (think its set now to 80Hz)

3) Do I set REW to use subwoofer test signal in Settings --> Soundcard or somewhere else.

Sorry if I appear dim (which I'm feeling right now).

Cheers,
Mark


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## Cathan (Jul 9, 2007)

I for one appreciate all of your questions, Mark. I feel like I'm learning this right along side you. :reading:


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## salvasol (Oct 31, 2006)

BritInVA said:


> 1) So do I physically disconnect the mains from the AVR?


Yes



> 2) Do I go into AVR and increase the current crossover (think its set now to 80Hz)


No, unless you'll be using something different, set it to the crossover you'll use.



> 3) Do I set REW to use subwoofer test signal in Settings --> Soundcard or somewhere else.


Yes, on REW you have two options: Speaker or Sub test tones...use Sub.

Don't worry about asking questions....I'm not an expert in REW, but I recall a little what I did when I use it the first time :whistling:


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## BritInVA (Feb 12, 2009)

OK, disconnected mains.

Reset level using sub signal to 75db but when running had low headroom so ended up increasing volume so was nearer 90db.

Here is resultant graph










Cheers,
Mark


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## brucek (Apr 11, 2006)

> Reset level using sub signal to 75db but when running had low headroom


And after the 75dBSPL was set at the listening position, did you then set the REW Input level to -12dB? And then run the Calibrate routine? Then Measure?

brucek


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## BritInVA (Feb 12, 2009)

brucek said:


> And after the 75dBSPL was set at the listening position, did you then set the REW Input level to -12dB? And then run the Calibrate routine? Then Measure?
> 
> brucek


Hmmm...now I think I may have forgot that part. :rolleyesno:

I'll re-run tomorrow. Having PC blue-screen-of-death issues and my daughter has friends over for a movie tonight so I need to tidy room.

So back tomorrow.

Thanks everyone for there help.

Cheers,
Mark


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## BritInVA (Feb 12, 2009)

Back to testing.

- Loaded yesterday's Soundcard cal file (assume don't need to redo each time)
- Loaded the mic cal file
- Disconnected mains
- Used Check Levels, AVR vol and SPL meter to get 75db at mic position
- Calibrated SPL

Run measurement but was getting headroom pop-up so increased AVR vol in steps (leaving target level at 75db).

This what I was seeing

SPL Meter Headroom
75db --------- 29.6
80db --------- 26.2
82db --------- 22.8
85db --------- 20.1
88db --------- 18.1
90db --------- 16

I'm I doing anything wrong here?

This is graph with SPL at 90db










Thanks,
Mark


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## brucek (Apr 11, 2006)

> Used Check Levels, AVR vol and SPL meter to get 75db at mic position


And, as I said above, did you .... _after the 75dBSPL was set at the listening position, did you *then set the REW Input level to -12dB?* And then run the Calibrate routine? Then Measure?_


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## BritInVA (Feb 12, 2009)

Don't know if this info about my room is useful

*Equipment*
- AVR: Denon AVR2807 
- Front Speakers: Ascend 340 SE 
- Subwoofer: HSU STF-2

*Room Treatments*
- Screen Wall: Acoustic cotton in corners and 2" OC703 for remainder of area (screen area also now 2" OC703)










- Side Walls: Fabric covered 1" OC703 from 8" to 54"
- Oak panelling and bar at rear (sure this hurts room but looks nice)

Finnished Room Pictures

















To sub is located in the right corner of screen wall, not really any other options for placement other than left corner.

Cheers,
Mark


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## BritInVA (Feb 12, 2009)

brucek said:


> And, as I said above, did you .... _after the 75dBSPL was set at the listening position, did you *then set the REW Input level to -12dB?* And then run the Calibrate routine? Then Measure?_


Do you mean the Sweep Level? If so that is -12db


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## BritInVA (Feb 12, 2009)

I changed battery in my SPL meter.

- On Settings, Soundcard with "Use Subwoofer to Check/Set Levels" I click on "Check Levels" and use the AVR volume to get SPL of 75db at the listening/mic position. 










- I then click on the Calibrate button on the top of the REW screen. Whait for SPL to settle and set to 75db










I then Measure but at this setting I'm getting <30db headroom

What am I missing? :help:

Cheers,
Mark


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## brucek (Apr 11, 2006)

> Do you mean the Sweep Level? If so that is -12db


No.



> What am I missing?


You're missing what I am trying to tell you for several posts.

Don't do anything else until you understand this statement.

*Raise the INPUT LEVEL to -12dB*

brucek


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## BritInVA (Feb 12, 2009)

brucek said:


> *Raise the INPUT LEVEL to -12dB*


Sorry for being dense here.........

Do you mean after I have Checked levels to be 75db I need to use the M-Audio Soundcard controls to increase the right chanels level to -12db.

Thanks for you patience

Cheers,
Mark


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## BritInVA (Feb 12, 2009)

Assuming thats what you meant I used the Souncards control panel to adjust right input.










Could only get it to around -19db

Run Measurement and Headroom is now 11.8db

And graph










Keeping fingers crossed :crying:

Cheers,
Mark


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## salvasol (Oct 31, 2006)

BritInVA said:


> Keeping fingers crossed :crying:
> 
> Cheers,
> Mark


:T ....that looks good to me :yes:

Just change it and show from 15Hz to 200Hz :yes:


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## BritInVA (Feb 12, 2009)

Like this :bigsmile:


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## brucek (Apr 11, 2006)

> I used the Souncards control panel to adjust right input.


Exactly, except adjust it to between (-12dB to -18dB) RMS while ensuring the PEAK level does not go over -3dB. 

The RMS level is the green/yellow information and the PEAK level is the red bar above the green/yellow information.

The arrows are pointing to the REW INPUT VU meter level (-12dB to -18dB) as a reference . You're at -21dB RMS (acceptable, but could be higher).










brucek


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## salvasol (Oct 31, 2006)

BritInVA said:


> Like this :bigsmile:


Yes.

Are you using any kind of EQ in your AVR???...I start with that to improve the response, also placement of the sub (move it around if you can), Do you have any acoustic treatment??? ....be prepared, the fun will start now :bigsmile:


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## BritInVA (Feb 12, 2009)

OK - Peak gets to no more than -4db and RMS between -15db and -12db










And the measurement graph


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## brucek (Apr 11, 2006)

Yep, looks good now.........


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## bmackrell (Aug 19, 2008)

Mark,

Looks like you've made a lot of progress since Thursday night (with help from the good folks here). Now that you are getting dialed in you can experiment with sub placements in the room (regardless of where you can actually place it) and maybe additional treatments.

Looking good,... keep it up. 

We'll do my theater next :bigsmile:

BillMac


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## BritInVA (Feb 12, 2009)

salvasol said:


> Yes.
> 
> Are you using any kind of EQ in your AVR???...I start with that to improve the response, also placement of the sub (move it around if you can), Do you have any acoustic treatment??? ....be prepared, the fun will start now :bigsmile:


Gave details of existing treatments on post 24. Unfortunately cannot add additional treatments (could remove some) and movement of sub is limited due to aesthetics.

Sub is currently in the front right corner......only other position is front left corner. Is it worth trying that.

Given this what are my choices? maybe a 2nd subwoofer, or a BFD?

Really appreciate any guidance or if due to aesthetic I'm stuck with what I have.

Cheers,
Mark


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## brucek (Apr 11, 2006)

> Given this what are my choices? maybe a 2nd subwoofer, or a BFD?


Given the sub response, I would be inclined to do nothing. It has no real problems.

A better judgment can be made after you add the mains (and do the same measurement you just did for the sub from 0Hz-200Hz) and adjust the sub phase to get the smoothest crossover.

brucek


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## salvasol (Oct 31, 2006)

BritInVA said:


> Gave details of existing treatments on post 24. Unfortunately cannot add additional treatments (could remove some) and movement of sub is limited due to aesthetics.
> 
> Sub is currently in the front right corner......only other position is front left corner. Is it worth trying that.
> 
> Given this what are my choices? maybe a 2nd subwoofer, or a BFD?


:duh: ...saw that post before.

Yes, try that left corner and see if it changes anything.

Can you borrow another sub (in case you don't have another) and try one on each corner???

A BFD will help, but if your AVR has an EQ you can start with that :yes:.


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## BritInVA (Feb 12, 2009)

brucek said:


> A better judgment can be made after you add the mains (and do the same measurement you just did for the sub from 0Hz-200Hz) and adjust the sub phase to get the smoothest crossover.


Subwoofer + Mains at Ph0










Subwoofer + Mains at Ph180


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## BritInVA (Feb 12, 2009)

salvasol said:


> Yes, try that left corner and see if it changes anything.


Can't hurt I guess :bigsmile:



salvasol said:


> Can you borrow another sub (in case you don't have another) and try one on each corner???


I'll ask around



salvasol said:


> A BFD will help, but if your AVR has an EQ you can start with that :yes:.


AVR is Denon 2807 not sure if it has EQ so will need to get manual out. I know it has Audyssey but really did not like LFE so I manually calibrated.


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## salvasol (Oct 31, 2006)

BritInVA said:


> Subwoofer + Mains at Ph180


I stay with this setup ....:yes:


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## BritInVA (Feb 12, 2009)

Just for kicks moved to Left corner

Subwoofer (left) only with Ph 0










Subwoofer (left) only with ph 180










Subwoofer (left) + Mains with Ph0










Subwoofer (left) + Mains with Ph180










So whats verdict is Right or Left better with Subwoofer + Mains with Ph180?

And is it worth going with BFD or leave as is?


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## salvasol (Oct 31, 2006)

BritInVA said:


> So whats verdict is Right or Left better with Subwoofer + Mains with Ph180?
> 
> And is it worth going with BFD or leave as is?


Can you post them together??? (is hard to compare if they're in different posts; I say left placement with 180 phase)

Try Audyssey and see if you like the results ...just write down the setting you have right now (unless you can save it in a memory) :yes:


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## BritInVA (Feb 12, 2009)

salvasol said:


> Can you post them together??? (is hard to compare if they're in different posts; I say left placement with 180 phase)


Subwoofer in Left corner










Subwoofer in Right corner












salvasol said:


> Try Audyssey and see if you like the results ...just write down the setting you have right now (unless you can save it in a memory) :yes:


I've tried Audyssey a few times and found it sets both center and sub too low.....and as far as I know as soon as you adjust a setting Audyssey turns off.


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## salvasol (Oct 31, 2006)

BritInVA said:


> I've tried Audyssey a few times and found it sets both center and sub too low.....and as far as I know as soon as you adjust a setting Audyssey turns off.


To bad. My Yamaha RXV-2700 allows you to tweek the PEQ after YPAO and keep the rest of the settings.

You can combine both graphs too, it will be easy to compare them (I think you use the measured tab) :yes:


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## BritInVA (Feb 12, 2009)

salvasol said:


> You can combine both graphs too, it will be easy to compare them (I think you use the measured tab) :yes:


Here you go but don't look like you can include target


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## BritInVA (Feb 12, 2009)

Now this is the Average of both so would this mean worth looking at adding 2nd sub?


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## salvasol (Oct 31, 2006)

BritInVA said:


> Here you go but don't look like you can include target


Yep, you can't include the target, but this is enough to compare both measurements ...I like left placement, as you can see is flatter than the right :yes:

Response looks good, is hard to tell if adding a second sub will help or make it worse...borrow one and try it.

What do you think??? ...Are you happy with the bass in your HT???


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## BritInVA (Feb 12, 2009)

salvasol said:


> Yep, you can't include the target, but this is enough to compare both measurements ...I like left placement, as you can see is flatter than the right :yes:
> 
> Response looks good, is hard to tell if adding a second sub will help or make it worse...borrow one and try it.
> 
> What do you think??? ...Are you happy with the bass in your HT???


I had not been totally happy with bass hence why embarked on this exercise to see how bad it was. My only other option is to build DIY subs to fit either side of the center speaker to get them out of the corner. Or I could make a section in the ajoining equipment room which would be about 8' along the left wall.

I'll leave sub in left corner to see if I can feel/hear a difference. I'll also put feelers out with some local HT'ers to see if I can loan a sub of size to fit. 

Is it best to get identical subs or a contrast?

Thanks everyone for all the help and patience on this learning curve.

Cheers,
Mark


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## salvasol (Oct 31, 2006)

BritInVA said:


> I had not been totally happy with bass hence why embarked on this exercise to see how bad it was. My only other option is to build DIY subs to fit either side of the center speaker to get them out of the corner. Or I could make a section in the ajoining equipment room which would be about 8' along the left wall.


I suggest you to start a new thread asking for ideas on the DIY section ...just post room dimensions, sketch of what you have and pictures; I'm sure you'll get a lot of suggestions there (maybe a coffe table sub near the bar in the back of the room :whistling




> Is it best to get identical subs or a contrast?


I read that is better to get identical subs, or at least with the same specifications ...:yes:


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## Cathan (Jul 9, 2007)

Wanna borrow my sub, Mark? :whistling: 

In all seriousness, the charts you are now getting is what I thought we should have gotten on Thursday. Really great news that you have only minor issues for real.


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## BritInVA (Feb 12, 2009)

Cathan said:


> Wanna borrow my sub, Mark? :whistling:


Ha,Ha - I'd have to knock 4' off the room length to fit your IB in :yikes:

Hopefully I can find someone with a more my size sub :heehee:


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## BritInVA (Feb 12, 2009)

Just for my own sanity as this was not clear in the help files.

After creating calibration file for Sound card with loop back

1) You just load in that calibration file for further testing (no need to create new everytime use use REW)

2) That adjusting the input levels of the mic has no impact on the calibration of the soundcard.

Cheers,
Mark


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## brucek (Apr 11, 2006)

> (no need to create new everytime use use REW)


Correct. That file is created for the soundcard channel once, and that's it.



> That adjusting the input levels of the mic has no impact on the calibration of the soundcard


Correct. The soundcard file accounts for any response weakness in the card and renders the card flat. It has nothing to do with the microphone.

brucek


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## BritInVA (Feb 12, 2009)

Thanks Bruce for all your help - would never have got there without you.

Appreciated.

Cheers,
Mark


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## BritInVA (Feb 12, 2009)

A loval NoVA HT'er who had seen my setup noted that my subs port faced forward into the room. Suggested I try with port facing rear (into the accoustic cotton). So I made some more measurements comparing the Subs port facing forward into the room and factng rear into the accoustic contton.

First just the Sub










And now Sub + Mains










Not sure what is best.

Anyone know?

Cheers,
Mark


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## salvasol (Oct 31, 2006)

BritInVA said:


> Not sure what is best. Anyone know?


Besides the 2db-3db difference below 50Hz is the response between 70Hz-100Hz ....Did you notice any change???:huh:


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## BritInVA (Feb 12, 2009)

At this time I've not tested enough material to be able to judge but if the objective is to be as close as possible to the target curve then based on the increased 2db-3db under 50Hz and the bigger dip around 95Hz the original port facing into room would seem logical to be the better of the two options.

Still trying to get access to another sub.


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