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Discussion Starter #1
Hello,
I finally found time to try a little more the REW software that I downloaded 3 months ago, using a ECM8000 + Edirol UA-25. For a "free" download, REW is quite impressive. I wanted to give you some initial feedback. "Vaut mieux tard que jamais" as we said in french.

I started by measuring the frequency response of a small Polk Audio loudspeaker, on a bookshelf, against a wall (The microphone was on a tripod, about 12-15 inch in front of the loudspeaker). The shelf is situated into a fairly small room into my house. I did a comparaison of the result using REW (v4.11) and using the FFT function from that popular "free" software: Audacity. In the latter case, of course, I had to "convert" the result of the FFT into 1/12 octave frequency bands, copying the large text file into Excel...). With Audacity, also, I had to use pink noise as a test signal, instead of a freq log. sweep...

The result?
1-Both curve (REW "smooted" to 1/12 oct, and the curve from Audacity) were very similar (some differences at lower frequencies). So far, so good! A good indication that things seem to work well...The result makes sense anyway for that small loudspeaker on its shelf...
2-REW is (much) easier to use. It's fun too.
3-REW provide a lot of information. For instance the RT-60 (I got 0.2 -0.4 seconds. The room is fairly small and (definitively not empty) filled, so that makes sense - I'll try to calculate it to check).

A few questions:
1- Using Pink noise VS frequency sweep as a test signal: Do your expect different response from the loudspeaker? Why?
2- How to interpret the (very nice) waterfall ? Is it only useful for RT-60? Speaker wall resonances?
3- Is it possible to use REW with Pink noise test signal ? Any advantages to do so?
4- Is it possible to analyse already recorded .wav files, as wity Audacity?
5- I did everything with the Edirol audio capture set at 44.1 kHz. Is that right?


Here again, I'm impressed. Look like a useful software that seems to work very well! Also, a very educative tool for audio enthusiasts, not only engineers...

Thank you
L P Simard
 

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A few questions:
1- Using Pink noise VS frequency sweep as a test signal: Do your expect different response from the loudspeaker? Why?
I wouldn't expect significant differences. They're both legitimate methods for looking at the response, so if interpreted correctly, the same conclusions should be reached.
2- How to interpret the (very nice) waterfall ?
Hard to say without seeing it. It helps you pick out peaks due to modes(extended decay times) from peaks due to other effects.
Is it only useful for RT-60?
I think the RT60 tab is more useful for that.
3- Is it possible to use REW with Pink noise test signal ? Any advantages to do so?
Sure. Go to spectrum or RTA mode. Best advantage is you can see changes in real time, rather than making time consuming sweeps in between.
4- Is it possible to analyse already recorded .wav files, as wity Audacity?
http://www.hometheatershack.com/roomeq/wizardhelp/help_en-GB/html/dataimport.html#top
5- I did everything with the Edirol audio capture set at 44.1 kHz. Is that right?
If that's what it can handle, that's what to set REW to.

Don't be shy about reading the help files :T
http://www.hometheatershack.com/roomeq/wizardhelp/help_en-GB/html/index.html
You can get answers much faster!:bigsmile:
 

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Discussion Starter #3
Thank you for the information. I guess, I should have started with those help files...
I will proceed with more tests...
 

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Hope your getting on well. Keep us posted!
 
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