[sdiy] Booster for Synthacon VCF

[Brett Maddaford]

Hi Michael

Is this an original steiner filter or a CGS one? Any schematics etc on
what you did?


Thank
Brett

-----Original Message-----
From: Michael Ruberto [mailto:frankentron at hotmail.com] 
Sent: Wednesday, 24 August 2005 11:44 AM
To: synth-diy at dropmix.xs4all.nl
Subject: [sdiy] Booster for Synthacon VCF


Hi

I was tinkering with the Synthacon VCF and added a simple FET amp to
boost 
it's output. To my suprise I got something quite more than I
anticipated. It 
does work properly - a 1Vpp signal in gives me a 2Vpp signal out with
the 
resonance cranked and a 1Vpp at min res. However, I also get the
sweetest, 
warmest, tube type sound I've heard lately. It's really quite delicious!

On the O-Scope I see a rounding off of the linear portions of the
waveform. 
With a sawtooth on the filter's input and cutoff completely open, the 
waveform is a quarter circle shape. It seems I am overdriving the FET.

Drawbacks, The VCF will not oscillate due to the loading down of it's
output 
tranny. Might be worth it to add an op-amp buffer between the stages.
This 
is basically a simple preamp and it can be used by itself or with any
other 
module too.

Give it a try, you won't believe your ears!

M. A. Ruberto