[sdiy] Env. Controlled 606 filter sweep methods?

[Plutonique9]

I'm interested in adding the ability to sweep the internal 606 Hi hat 
and Cymbal filters by their associated Envelopes. I'm looking for a 
way to implement this in its most basic form, only a toggle switch to 
turn On/Off this function.

Now with the BPF's, the cutoff is controlled by a resistor going to 
ground in a Op Amp configuration. 

I have been able to lower the cutoff of the HPF's by adding a 
resistor in parallel with a cap.

So I guess, I would be needing a very basic Voltage controlled 
resistor. I'm thinking this could be implemented using a FET or 
transistor.

All the same, I'm quite hazy in how you would implement this.
Thankyou

-- Plutonique9, Plutonique9 at symbiocom.com

http://www.mp3.com/Plutonique9