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

[Hugh Blemings]

Hiya Neil, All

In delurking I'll preface the following by observing that I'm firmly in 
the camp of "knowing enough to be dangerous"... :)

> [...]
 >
> 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, as I understand it, that's the way a lot of the analog path is 
controlled - by DAC's for each parameter that needs to be controlled.

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

I gather the common approach here is to use a digital potentiometer, but 
I daresay others on the list could answer with more authority on this one :)

This is I think the approach that's been used in various forms for 
pretty much every digitally controlled analogue synth from the 80's on.

Happy Hacking,
Hugh