[sdiy] vactrol panning (across 4 outputs?)

[Tom Wiltshire]

Sorry Alfred, I'm not quite clear what you're trying to do.

Do you want the two extra channels to be copies of the existing two channels, or are you aiming to build a 'quadraphonic' version of the circuit?
Or do you have a 'four channel scanner' circuit in mind, where the output can be 'panned' from output 1 to output 2 to output 3 to output 4 under the control of a CV?

The circuit itself looks to be a pair of "optical" VCAs, as used in many famous compressor designs (very simple audio path, so low noise, and the slow LDR response gives a natural sound). The vactrol's LEDs are driven with a current mirror, which provides the panning action (one goes up whilst the other goes down).

Thanks,
Tom


On 16 Jan 2011, at 05:00, alfred.pear at gmail.com wrote:

> hi synthesists -
> 
> i'm sure many of you are familiar with this very elegant two-channel
> panning circuit, using two vactrols (based on a buchla design,
> apparently):
> http://www.simple-answer.com/vac-panner.jpg
> 
> i feel like there must be a way to nest and scale several transistors
> in there to make this circuit response across four channels of
> output....but i'm not a very skilled designer..
> 
> any suggestions?
> 
> sincerely,
> a. p.
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