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Moorer's reverb Combfilter gain coefficient calculation
December 17, 2017 - 10:40 pm
Member Since: December 25, 2014
Forum Posts: 8
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Hi Will i was going through the section of your book where you go over moorer's reverb. I was able to implement the moorer's reverb and used the settings in the table from pg 375. However I wanted to see if I can come up with the same comb filter gain coefficients myself, but I can't seem to wrap my head around the math behind it.

I took the equation from 11.9 where the gain = 10 ^ (-3 * D * Ts/RT60) where D is the delay length (which I believe is in samples) and Ts is the sampling period and RT60 is reverb time (which I believe is in seconds). So I plugged in the 1st comb filter values where gain coefficient is 0.46.

So taking my assumptions, I plugged in the variables like this: 10 ^ (-3 * 2400 * (1/48000)/2) where D is 2400 samples (50 ms at 48kHz) and Ts is 1/48000 and RT60 is 2 (i assumed leave this in seconds). However when I calculate this my coefficient for the first comb filter is 0.841395 not 0.46.

I also saw the note underneath the table where g is 0.83 and RT60 is 2 seconds and was wondering if equation 11.9 was used to calculate this as well.

I know I am definitely missing something here I was hoping you can point the flaw in my logic or any thing that I missed.

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