VCO Synthesizer?

Question on Big Briar Series 91.
I have not seen the thing.
I think that it is a very beautiful tone.
Is for this Theremin, is not the heterodyne method voice but VCO installed?

Good question. The series 91 technical bulletin says:

"The tone generating circuitry uses contemporary analog synthesizer technology to emulate the waveforms of Professor Theremin's instruments."

Unfortunately, that doesn't give us enough detail to answer your question.

You might try contacting Moog Music via e-mail to see if you can find out more information. If you do, please let us know what you find out.