[sdiy] 3320 as SVF

Tony Allgood oakley at techrepairs.freeserve.co.uk
Sat May 19 10:53:24 CEST 2001


Hi all,

This is a topical thread for me right now too. I have a OB-Sx module
racked up and in use as a little mono. Very nice, I like its sound but
for one thing. The filter suffers from very bad CV bleedthrough. Now it
features a 3320 as two pole filter, similar to that in the OB-8, but
without the four pole or the switching found in later Oberheims. Has
anyone else noticed undesirable bleedthrough when Q is low?

The datasheet for the 3320 has a little trimmer added to one of the
supply rails to control CV rejection. I added this, but it made little
effect. Any ideas? Bad 3320, or just bad design in the first place?

Regards,

Tony Allgood  Penrith, Cumbria, England

Oakley Modular Synth and TB3030:
www.techrepairs.freeserve.co.uk/projects.htm
My music: www.mp3.com/taklamakan






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