Is it really controlled by only one pot, or does the knob do something out of the ordinary? My first thought is that maybe we're looking at three pots controlled by one knob, and each act in their own third of the range. Or it's just a rotary encoder that controls some DACs.
We don't know. I think it is "mostly" analog, probably some analog switch is playing a role (Moog does use 4066s, for example the "open" Werkstatt).
I think it is an interesting exercise to think it analog.
i actually have some kind of idea on how to do it in analog but it's complicated enough to be difficult to draw it as a block diagram
could you describe the idea in text?
I was thinking that starting with squarewave followed by integrator, changing the DC offset of the squarewave yo get sawtooth. And increasing even more you begin to "squarize". But then pushing even more we need to change the pulse width... I don't see how it can be done in a continuous way...
The MCU solution today would be the cheapest and most repeatably stable and reliable, around 2 dollars, all on 1 chip, only need 5v supply, with your choice of any waveform output, but, you will need to do some programming.
Thank you for your links Brian, yeah if it were me I would software synth everything, as I'm a full time software dev.
In fact another project I'm planning is a fully digital FPGA based theremin (based on some really serious works someone is doing at thereminworld).
This synth, however, is kind of a request from a keyboard player I know. The thing is that musicians appreciate "analog". I was thinking that some of the imperfections of analog "might" be desirable for them, including slightly imperfect tuning, imperfect waveforms, etc.