audio processing

[Sebastian]

Hm, I've tried to calculate the coefficients for a low pass filter with these formulas http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt

Im comparison to the excel sheet I had to set in the "center frequenzy" and not the -3db frequenzy. So when calculating with 2000Hz (2100 in the sheet) and Q=1, I got the following results (41000Hz sample rate) for a low pass filter:

formulas from the link:
b0 = 0.0256695991
b1 = 0.0513391983
b2 = 0.0256695991
a1 = -1.8973216034
a2 = 0.3674095060


Excel sheet:
b0 = 0,026936651
b1 = 0,053873303
b2 = 0,026936651
a1 = -1,343504439
a2 = 0,451251044

I think the values are quite similar, however, I don't know if it's correct..
The next step will be the pic calculation...

regards
Sebastian