Tuning speaker / room response?


I finally did an experiment this afternoon to check out my speaker and room response. The graph below shows the results:

I got this using the Stereophile Test CD 2 tracks 15 through 18 using my system. The first one provides pink noise, the others give warble tones at the various center frequencies shown in the chart.

A Radio Shack SPL meter, in fast mode, C weighted, was used to to capture SPL levels. The meter was in the 80dB range. As C weighting rolls of above 10kHz, I did not show the rest of the spectrum.

Now this does not look all that flat to me, but I have never done this before. Can anyone give me an opinion on how good or bad this looks?

Also, it looks to me like a little room tuning might help. Anyone have any suggestions as to where to start with this?

Niels.
njonker
Jaycee, thanks for the response.

I ended up buying a different instrument to test with, after some people had pointed out the flaws in the methodology I was using here, and using different test methods. Some of the things seen in the graphs above were artifacts from the RS meter used, but not all.

Using my Terrasonde The Audio Toolbox 2, a handheld, calibrated SPL meter, tone generater, and real time spectrum analyser, I did the tests again with pink noise and slow C weighting. I found that I had a high-frequency and a bass problem. The high frequency problem was mainly caused by reflections from the walls it seems; hanging a rug about 2.5" from my back wall solved most of that. Right now, my in-room response abve about 400Hz is within +/- .5dB! The difference is amazing... Imaging improved incredibly, and the system sounds 'calm' now.

As for the bass problems, I tried building some traps using the mthods found in an article on headphone.com, but I made some calculation mistakes, so they did more harm than good. Then I found the ASC website, they sell accoustical products to deal with room acoustics, and offer a free consulting service. I have provided them with room and frequency response information, and they are working up a solution for the bass problem. We shall see what comes out of it...

Niels.
Njonker, is it possible for you to show the graph of your room before treatment with the toolbox. I've been intrigued by this product, and was wondering just how different the results were.
Niels,

The correction for the Radioshake meter are as follows. Replot the response by ADDING the correction values to measure values and then seee where you stand.
Freq correction
20 6.2
25 4.4
31.5 3
40 2
50 1.3
63 0.8
80 0.5
100 0.3
125 0.2
160 0.1
200 0
250 0
315 0
400 0
500 0
630 0
800 0
1000 0
1250 0
1600 0.1
2000 0.2
2500 0.3
3150 0.5
4000 0.8
5000 1.3
6300 2
8000 3
10000 4.4
12500 6.2
16000 8.5
20000 11.2