# Room Acoustic Treatment with REW



## Firochromis (Jan 26, 2010)

Hi, I' m a music lover and have a humble system in my living room. I want to treat my room acoustics since I guess it's awful in that manner. First of all, it has an irregular shape, and the system is placed to the one side of the room. *Secondly, there is A LOT of window in the room and one big aquarium (not now, but in a few months' time)* :help:

This is my room:

*Listening point is marked with red figures.* Speakers are some 10 feet between, and the right speakers has 3 feet clearence with a huge window. Left one has a bigger open area to its left. Speakers are 1.5 feet away the wall, and listening point is just in front of the wall (no area behind). 








Yes, light blue shapes are windows. 

























I mostly listen to classic music but also jazz and rock. Since I need a full spectrum treatment, graphs' scales are from 15Hz to 20KHz.

So, I have been reading almost three weeks in this forums and I get ECM8000, XENYX 802 and UCA 200 with some cables and get them connected using the table in this link. :

http://www.hometheatershack.com/for...ards/10001-rew-cabling-connection-basics.html

*I also used the optional Y splitter to feed the stereo amplifier from both channels and connected the line out (L channel) of the UCA 200, to its' own line in (L channel).* Anything wrong here? *Should I feed the speakers seperately since the unsymmetry of the room?*

This is my Soundcard calibration graph:








I calibrated the ECM8000 from the file in the downloads section. Nothing special there.

This is will be a long term thread for me. I'll apply treatments in some months so want to go step by step. Although I made a measurement and want to share, my first step is measuring technics. In the Settings of the REW software, I didn't touch anything, so sampling rate is 48kHz; input channel is right; and using subwoofer for check/set levels. (There is no subwoofer connected to my stereo amplifier). *One problem is, when I check levels with this settings, the colored three bars are never at the same level.* "Out" and "left" are almost equal but "right" is very low. Is this a problem?

In the Analysis tab, all the upper values are Tukey 0.25. If I remember well, one of these settings were different but I changed it to "Tukey 0.25" Any prooblem here?

And lastly, while making measurements I placed ECM8000 not facing up, or not facing directly to stereo system. It's some 45 degrees between that values.

If everythiing seems ok, I'll post my first measurings. After then I'll be taming poor acoustics :boxer:

Regards


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## Wayne A. Pflughaupt (Apr 13, 2006)

Welcome to the Forum, Firo!




> Anything wrong here? Should I feed the speakers seperately since the unsymmetry of the room?


It’s a good idea to measure the main speakers separately, especially in an asymmetrical room.




> One problem is, when I check levels with this settings, the colored three bars are never at the same level. "Out" and "left" are almost equal but "right" is very low. Is this a problem?


The only one to worry about, (L or R) is the one corresponding to which channel of the sound card you are using. You should only be using one channel of the sound card.




> In the Settings of the REW software, I didn't touch anything, so sampling rate is 48kHz; input channel is right; and using subwoofer for check/set levels.


Select the Main Speakers or Subwoofer setting depending on what you intend to measure.




> And lastly, while making measurements I placed ECM8000 not facing up, or not facing directly to stereo system. It's some 45 degrees between that values.


Our calibration file was generated using horizontal orientation, so the mic should be pointed directly at the speaker (orientation doesn’t matter for subwoofer measurements, however).

Regards,
Wayne


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## cyberbri (Apr 27, 2006)

Wow, that's a tricky room. You'll have highly reflective glass close to one side with the wall right behind the LP, and the other side is much more open with it open behind the LP as well. You'll have a lot of reflection coming from the right and the left will be pretty good. With the LP against the wall, bass response will also be pretty muddy. It would help the bass and with the reflections of higher freqs off the rear wall if you moved the LP forward 2-3 feet. You're already almost 11' back from the speakers, so moving forward wouldn't hurt. You can also put a few panels or something on the back wall behind the LP so the sound doesn't bounce back as much and closer simulates the properties of the rear left side.

You can see about getting some sort of thick curtain to drape across the aquarium at night that would help with those reflections. 

Good luck!


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## Firochromis (Jan 26, 2010)

Thanks for the wonderful advices.  Unfortunately I can' t move the LP to forward. There is no WAF in my situation, but.. this is my living room  Though, I know I' ll have to use some sort of treatment above the LP.









This is the measurement screen seen during the measuring process. What I' m talking is this, these bars are not at the same level. And I don't know if they should be or not. My computer is connected to Behringer UCA 200 with an usb port, and R line out of the UCA 200 is connected to stereo amplifier. ECM8000 is connected to XENYX 802 with a XLR cable, and XENYX 802 is connected from the R line in of the UCA 200.

*My measurements are always averages at 105 dB.* But in the other posts I see the graph move horizontaly at something like 75 dB. In the "Posting Graph" thread its also advised to calibrate the graph showing 45-105 dB in the vertical axis. But this is not appicable for me. what would be reason for this ~30 dB difference in graphs?

Sorry if this is a silly question but, I want to be sure. While saying, "_the mic should be pointed directly at the speaker_" you mean, its directed just to the single speaker in the measuring process (then turn it to other speaker keeping it horizontal) or direct it to forward (to the TV in my situation).

Best Regards..


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## laser188139 (Sep 19, 2009)

The levels you are seeing in the screen image you posted indicate the voltages on the line out and line in signals. They tell you how close you are to clipping on the incoming side. This is different from, although proportional to, the levels displayed in the graphs. What you see in your image is typical, if maybe a little low, you want the right hand bar to allow lots of head room so that clipping does not occur on the line in signal when peaks are measured. 

The graph level is determined by what you calibrated REW to identify as 75dB in the Settings->Check Levels procedure, or with the SPL Calibrate button above the graphs. Because of possible changes in the volume controls on the computer, or the volume control on the receiver, you must Calibrate REW to know what 75dB is at your mic position at the start of each session. All the graphs are relative to this reference value you told it, when you calibrated it to whatever number you read on your trusty SPL meter. 

Bill


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## Firochromis (Jan 26, 2010)

Hi all,

I've started this thread looong time ago and couldn't come to an end due to some personal problems. But now I have time and energy to finish this project. I want to build bass traps behind the speakers and diffusor between speakers and listening position like the one in the link. I can also build a diffusor to ceiling.

http://www.pmerecords.com/Diffusor.cfm

Below is REW output in my room. (Right speaker is BLUE; Left speaker is RED)

So, I need a final help to decide the dimensions of traps and diffusors.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Hi firo,

In this corner of Home Theater Shack we mainly specialize in helping people with REW and equalization issues. If you need advice on room treatments – what to use, how to use them, how to make them etc. – jump over to our  acoustics forum .

Regards,
Wayne


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## avpman (Dec 27, 2010)

Sorry for the NOOB question. But can someone tell this thick headed Italian (me) how to overlay two measurements like this guy did with his left ad right readings? Also, how to change their colors.

I apologize if this question is in the wrong thread. But I wanted to reference his graph and I'm so new I don't think I can post links yet.

Thanks in advance.


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## avpman (Dec 27, 2010)

avpman said:


> Sorry for the NOOB question. But can someone tell this thick headed Italian (me) how to overlay two measurements like this guy did with his left ad right readings? Also, how to change their colors.
> 
> I apologize if this question is in the wrong thread. But I wanted to reference his graph and I'm so new I don't think I can post links yet.
> 
> Thanks in advance.


Found my answer on the "Measure" tab. :clap:


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## Firochromis (Jan 26, 2010)

So, no thick headed Italian around here


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