[sdiy] Ray Wilson's SV VCF with +-15V

[Ray Wilson]

It must be this one:

http://www.musicfromouterspace.com/analogsynth/STATEVARVCFFEB2006/STATEVARVCFFEB2006.html

Since its the only one that will oscillate.

It should not be acting the way you have described. You should only get oscillation near the end of the max resonance pot travel. Are you certain that all component values are correct especially those around the Res and COF pots. There are resistors in the circuit designed to limit the voltage range that the pots can deliver (COF R1, R5) and (RES R48, R52). If you need to adjust the range you can adjust them however when I tested this on +/-12V and +/-15V and I saw normal behavior. Also check the values around the VC resonance circuit. I'm not sure why you would be seeing what you've described under normal circumstances. Unsoldered component? Unsoldered off-board wire? Wrong value component?

Here are some troubleshooting suggestions:

http://www.musicfromouterspace.com/analogsynth/troubleshoot.html

Ray
  ----- Original Message ----- 
  From: Benjamín Velasco 
  To: Synth DIY List 
  Sent: Tuesday, March 21, 2006 4:12 PM
  Subject: [sdiy] Ray Wilson's SV VCF with +-15V


  Hi you all!!  I recently finished this module from Ray's site using my +-15V PSU. I seems to work but the ranges of the pots are too extreme. It starts to oscillate as soon as I start moving the resonance pot, and also i cover the entire CutOff freq range near the center position of the COff pot. Can anybody help me figuring out what values to change so the response is like the +-12V version?. Or maybe it's simpler to use a couple of voltage regulators to get +-12V??. Thanks!!! 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://synth-diy.org/pipermail/synth-diy/attachments/20060321/a771b4bd/attachment.htm>