[PD] Csound opcode Moogladder to Pd

Frank Barknecht fbar at footils.org
Wed Aug 27 10:08:13 CEST 2008

Anton H?rnquist hat gesagt: // Anton H?rnquist wrote:

> > The filter response gets nasty and loud if the center frequency is near
> > or above the sampling rate. Maybe it should be restricted as well. But
> > then, resonance at 1 will make everyone jump, too...
> Yeah I noticed that aswell. I think the Csound-version has cutoff
> restricted to 0...1, which is 0...11050 in hertz.

Only resonance is restricted to 0 and 1. It is in the pd version as
well. I made some tests now and it seems it's not the cutoff frequency
alone that makes the filter run wild. With resonance set to 0 a cutoff
of 96kHz when running at SR = 48kHz doesn't go wild. But set resonance
to 0.1 and it runs away. 

So in the end I'd say, just be careful and if in doubt [clip~] your
input values. 

Another issue may be denormalization, so some PD_BIG_OR_SMALL checks
could be useful.

Frank Barknecht

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