Re: [sdiy] state variable filter oscillating

[Roman]

See here:
http://sowa.synth.net/m_pics/m_vcf.gif
for SVF looking probably like yours. Notice 2 zeners in the feedback of last opamp. They remowe the "like crazy" part of filter oscillation. And don't forget to put those RC networks to ground at inputs of SSM2164.

Roman

---- Wiadomość Oryginalna ----
Od: mark s <djarum11 at mindspring.com>
Do: synth-diy at dropmix.xs4all.nl
Data: Sat, 19 Jun 2004 22:29:50 -0400
Temat: [sdiy] state variable filter oscillating

>hi, i've built a state variable filter with a TL074 and an SSM2164. it is 
>oscillating like crazy when i turn my frequency up above, oh i dunno 6000Hz 
>*and* when the resonance pot it turned way up. without getting deep into 
>the circuit itself, are there some basic principles i should look for in 
>order to troubleshoot ?
>
>thanks!
>mark
>
>