I can't get that damned filter to work. I've been trying to match the output of kingshriek's script to what (I think) I should be getting and it doesn't correspond.
Given f=1.0 and different q values I end up with cutoff F at 9-15kHz. You'd think with f that high it should easily go up to 22kHz (and above). On the other hand, if I'm reading the figure right, I should expect F as low as 4Hz for f=0.25 and about 50Hz for f=0.5
The Q has range of -3 to 20.25dB: Q [dB] = 0.75 * (reg_val - 3) where reg_val is 0 to 31.
Is there a clever way to figure out the filter equation given some points with f and resulting cutoff F known? Assuming Q is neutral, that is 0dB.