[sdiy] analog synths with digital controls? how does that work?

[Neil Johnson]

neil harper wrote:
> so i'm wondering, how are these analog synths able to save/recall
> settings and be modified through a computer?
>
> there's gotta be a digital layer between the knobs and the analog parts
> of the circuit right? so does that mean that it's sampling the position
> of every knob (which i guess it can multiplex) and then using DAC's to
> output the required control voltages for all of the knobs (a dac channel
> for each knob)?

Yes.

> what about things that aren't typically voltage controllable, like the
> resonance control of a filter..

Why do you think resonance is not CV-able?  Quite a lot of filter 
designs these days have CV-controlled resonance, as its mostly just 
adding another VCA in the feedback path.  And if you're using something 
like the SSM2164 then you've got lots of gain cells to use for the 
filter, and likely have one left over for resonance.

So, yes, make everything CV-able, and use a DAC and a bank of S/Hs to 
generate lots of CVs.

Neil
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