IIRFilter Slope


#1

Just a quicky…

Does the IIRFilter operate like a brick wall, or slope, regarding frequencies? I’m trying to make a simple 3 band EQ and can’t quite figure it out. I’ve split the audio buffer into 3, (1x low pass, 1x high pass, and 1x High pass then low pass as middle pass band) but it seems to attenuate the crossover frequencies (or some frequencies anyway). I’ve set the cutoff for all the filters at 400hz and 12Khz. I didn’t use shelf or band pass filters as I presumed they had a slope. Should I be taking into account some form of slope?

Many Thanks,
Mibix


#2

http://www.musicdsp.org/archive.php?classid=3#236

and of course

http://code.google.com/p/dspfilterscpp/

You can see how the IIR filters operate.


#3

Cheers.