[sdiy] Synthancon VC-Resonance

[jeff brown]

You could try Yves Usson's opamp variation so that you're dealing with a 22k variable resistor instead of 2k

http://yusynth.net/
http://yusynth.net/Modular/EN/STEINERVCF/index.html

Or try a VCA style approach like Charlie Lamm:

http://www2.charlielamm.com/synth/
http://www2.charlielamm.com/synth/steiner/cgs35wire.pdf

Or go the FET route. I was planning on trying the Vactrol approach with a VTL5C10 (some day). 
I think I heard somewhere that the Cyndustries filter uses something similar.

Jeff
  ----- Original Message ----- 
  From: nathan settembrini 
  To: send 
  Sent: Tuesday, May 02, 2006 7:26 PM
  Subject: [sdiy] Synthancon VC-Resonance


  Hi,
  I am doing a project for the Theory of Music Synthesizers class at Georgia Tech.  We have put together the Synthacon VCF filter (http://www.cgs.synth.net/modules/cgs35_syntha_vcf.html ) and are trying to add voltage controlled resonance to the circuit.  We have tried using a JFET as a voltage controlled resistor to replace the pot but think we were overdriving the amp and getting a lot of noise.  The other thing we tried was using a Vactrol to replace the pot, but can't figure out a way to get the resistance low enough (without supplying rediculous amounts of current) to replace the 1k pot.  Does anyone have any ideas?  Can the 2k2, 1k, and 1k pot all possibly be scaled to larger values and the circuit still function properly?  Thanks 

  Kyle
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