[sdiy] PAIA 9730 Resonance Problems

[Chris Williams]

G'day diyers,

I've built the Paia 9700 series a while ago and I am generally pretty 
happy (I have modded it a bit - mostly physically). One thing that I 
have had gripes with is the Dual SVF module that suffers from 
uncontrollable squawking at high resonance (others have experienced it 
too - see http://www.unease.se/mp3/Unease_P9700s_Bass1.mp3 for an 
example of the problem). I'm still coming to grips with filter circuit 
theory, but I  want to have a crack at fixing it :). The resonance 
feedback path seems different to many other SVF's I've looked at. The 
schematic is at http://www.paia.com/9730sch.gif. Can anyone give me any 
advice as to what I should look at changing? Or has anyone had a similar 
problem?

Cheers,

Chris.