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In room response

Hello, Lately I have noticed more talk of in room freq response measurements. It has been mentioned in regards to room treatment, subwoofers and their intergration, speaker placement, room size, crossover points, listening volume levels, speaker choices in regards to the type of music you listen to and a myriad of other reasons. I for one fell it is quite important and others seem to disagree to its importance in playback of recorded music.

This thread would be a great place for members to discuss its importance, ramifications, reason for being and to discuss results.

I have seen a few members who allready have posted results of the measurements under their "systems page". I just recently posted my freq response and waterfall graph on my "system" link.

I am quite sure that there are members who have allready done in room measurements of freq response, waterfall and RT60 or other measurements. If you are new to this, a program can be downloaded for FREE at the Home Theatre Shack, it is called the Room EQ Wizard. See link below. It would be used for mesurment only for our purposes, although it can be used with equalizers such as Behringer if you so desire.

http://www.hometheatershack.com/roomeq/

The only thing you need to provide is a sound level meter, which everyone should own, even if you don't use this program. A very inexpensive one is available from Radio Shack and is a welcome addition to any audiophiles toolbox.

I will start off with my freq response from 15-200 hz at 74db reference level posted here;
http://cgim.audiogon.com/i/vs/i/f/1208699468.jpg

Waterfall response 20-116hz posted here;
http://cgim.audiogon.com/i/vs/i/f/1208644826.jpg

Waterfall response 116-210hz posted here;
http://cgim.audiogon.com/i/vs/i/f/1208645085.jpg

Anyone else?

Bob
acoustat6
jylee
306 posts
 
I've played with Room EQ Wizard a few years back. It is a very useful and powerful tool. Here's one measurement I have taken previously.

Revel M20

The system back then was Revel M20 and Classe CAP-151 combo.
strabo
15 posts
 
This could be a fun thread. Your rooms are much better than mine.

Here is my before graph. This was my initial FR measurement before doing any room treatments or changing speaker placement.
[URL=http://cgim.audiogon.com/i/vs/s/f/1208799876.jpg]Original[/URL]

After moving the speakers and fixing quite a few trouble spots.
[URL=http://cgim.audiogon.com/i/vs/s/f/1208799877.jpg
]Current[/URL]
I've actually made a few changes since this measurement and need to get a new graph and waterfall.
acoustat6 OP
357 posts
 
Hi Jylee, Thanks for posting, yes the EQ Wizard is a great tool and one that is quite revealing.

Hi Strabo, This very well could be a fun thread, thanks for saying so. It also can be very informative. Great to see the change in your freq response, in the before and after. Good idea and I should post mine to also show the changes from speaker placement, bass traps etc.. It also would be great to see your most recent measurements.

Bob
chadnliz
3,736 posts
 
I would like to do this but dont really understand it all, I have a Behringer unit, Mic and test discs but I dont know if I have the right unit to do this and help on HT Shak was sorta vague and inconclusive...thos there is alot of nice folks over there trying to help.
acoustat6 OP
357 posts
 
Hi Chandliz, It is actually quite simplie, even if I did have to ask for assistance from my brother!

You dont need the Behringer unit to do this, so just put that to the side for now along with the test disc as the REW provides its own test signals.

You dont need the micropone either at this point but later on it can be used if you so desire, you know upgrading and all that.

Do you have a radio shack or other sound level meter? If so, that is used for its microphone capabilities as well as the SLP meter.

The first thing to do is download the REW software (for FREE, its for free, I love that!) current version is V4.11


The second thing you need to do is calibrate your sound card on your computer. You need a cable to go from the speaker or headphone out to the mic in, you are running a loop out and then back in to your computer to calibrate the soundcard. The software put out tones and then it runs back into the computer and compares the output to the input and corrects for any level problems on the soundcard.

Now you have the free software loaded and the sound card of your computer calibrated for the software. You need a cable from the speaker or headphone out of your computer and run it into an aux input of your preamp. So it is most likely a 1/8" jack to RCA cable.

You are almost ready to make a measurement but first you have to calibrate the Radioshack SPL meter. Again you need a 1/8"cable at the input of you computer mic in and a single RCA to the input of the Radioshack SPL meter. There are controls at the top where it says calibrate and run the test to obtain 75db reference level (or one close to that as you may need to adjust up or down depending on the the steps in your stepped attenuators if you have them such as I do.) You then need to mark the volume control position as every test is taken from the exact same level for obvious reasons.


Then run the test and post it here.

Bob
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