[sdiy] Digital accumulator VCO core?

Aaron B. aaron at zadzmo.org
Wed Feb 10 17:24:19 CET 2021

On Wed, 10 Feb 2021 08:34:11 +0000
Guy McCusker <guy.mccusker at gmail.com> wrote:

> > But you did give me an unrelated idea, analog tricore VCO + a series of
> > multiplying waveshapers + tri to sine converters... a lot of parts, but
> > a potentially interesting form of additive synthesis.
> That's essentially what happens inside the Buchla 148 Harmonic
> Oscillator, although I think that might be a saw core with a triangle
> shaper first of all. I'm pretty sure Mark Verbos's take on the same
> idea uses a tri-core.
> Guy.

Had to look this up - I'm admittably not as familiar with Buchla gear
as I should be - this is a fascinating module.

This also makes me think of the Poly 800 tone generator - four square
waves at different octaves, each switchable on/off, and a square/saw
switch that simply adjusted their relative amplitudes. I've often
thought of cloning it with a 4 bit digital divider and a standard VCO
clocked 16x higher than normal. Going "backwards" with a triangle
frequency doublers might work as well and be easier to tune, at the
cost of more parts.

Aaron B. <aaron at zadzmo.org>

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