[sdiy] Adding CV jacks to a synth...

[Tim Parkhurst]

> -----Original Message-----
> From: DTK [mailto:aurastar at cox.net]
> Subject: [sdiy] Adding CV jacks to a synth...
> 
> I've been spending some time with a schematic, and it got me wondering...
> 
> What parameters on a synth can be controlled via CV?  That may be a broad
> question... Maybe it should be what sort of things generally can *not* be
> controlled via CV.
> 
Well, it depends on the synth. Most analog synths out there will have
voltage control of VCO frequency, VCO pulse width, VCF Frequency, and VCA
amplitude. I mean, even if you look at something reasonably versatile like
an Odyssey or a Mini Moog, those are the only voltage-controlled parameters.


Adding voltage control to other parameters usually means modifying or
replacing some of the existing circuitry. Things like envelope times and LFO
rates are usually not voltage controlled in older analogs.

If you have a programmable analog synth, something like a Source or an OB-X
or Prophet 5, then you are dealing with circuitry that has been designed
from the ground up (no pun intended) for voltage control. On the OB-X for
example, the voice cards have voltage control of every "knob" parameter
(these are things controlled by turning a knob, rather than just on or off
with a switch), so this includes things like VCF resonance, modulation
amounts, envelope times and LFO rates. 

You can add a lot of versatility to a synth by adding other jacks too.
Things like outputs from the VCOs, envelope generators and LFOs, and
external inputs to the VCF and VCA. 

Just some thoughts. Remember that 1) you may lower the value of some
'collectible' synths by extensively modifying them (this is usually not a
big deal, especially if you don't intend to sell it) and 2) have fun with
it!


Tim (lower value, not collectible) Servo



> Sorry if my question is unclear... it's been a long time since I've had to
> really study a schematic, and frankly, it's kicking my ass...
> 
> Thanks
> 
> D
> 
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