[sdiy] Improved VC Pan circuit

[Scott Bernardi]

Yes, at the time I built it (1981) I used 3080's. If I was doing it
again now, I would use LM13600's or LM13700's and take advantage of the
input diode biasing. 
I whipped up an improved VC Pan circuit this morning, with exponential
control of the OTA currents (smoother transition in loudness). "Ask, and
ye shall receive...."
I haven't tried it yet, so it might need some tweaking.  See it at
http://members.home.net/sbernardi/elec/improved_vcpan.gif
One more thing I would do is create a dedicated LFO summed into the
first opamp. Use a rate pot with a switch so you can disconnect it.


You could easily do this circuit with a CEM3330 dual VCA (or
equivalent). You would use the similar configurations for the CV summing
opamps, but they would drive the CV inputs of the CEM3330 directly.

If you REALLY want to go fancy with a pan circuit, go for a quadraphonic
pan with a quadrature LFO to drive it. You could use a joystick for the
initial PAN position. You'd have to output it into a quad amplifier, but
you could do neat things like have the signal circle around the room
(ELP did that on that last sequenced part of Karn Evil 9 [part 3?]. I
saw them in concert in 1972. Very impressive).




Florian Anwander wrote:
> 
> Hi Scott
> 
> > As far as circuits that use CEM chips, see my website at
> > http://members.home.net/sbernardi/elec/ogee_home.html. My old synth OGEE
> > used a lot of CEM chips, and there are a number of schematics posted
> > there.
> Nice thing you did then.
> 
> I am interested in the VCPAN. Which VCA did you use. Is it a CA3080?
> 
> kind regards
> --
> Florian Anwander                  |ConSol*  HP-Support
> Tel.   +49.89.45841-133           |Consulting&Solutions Software GmbH
> Fax    +49.89.45841-139           |Franziskanerstr. 38, D-81669 München
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-- 
Scott Bernardi
sbernardi at home.net