[sdiy] Digital accumulator VCO core?

Aaron B. aaron at zadzmo.org
Fri Feb 12 16:30:22 CET 2021

On Thu, 11 Feb 2021 21:18:22 -0800
Brian Willoughby <brianw at audiobanshee.com> wrote:

> Isn't the Poly 800 circuit just a cheap 4-bit DAC?

I guess when the waveform is set to 'Sawtooth', it acts that way. Set
to 'Square' all four bits on the DAC's digital inputs have identical
amplitude, instead of being scaled.

Here's a relevant snippet of the owner's manual:

Will all four octaves enabled, the sawtooth wave isn't pure but it
worked well enough. All four with waveform set to square sounds like a
pipe organ.

The real magic, IMHO, is disabling some of the octaves/bits. Having
only 8' and 4' turned on could make some nice LoFi woodwind-like tones
after passing through the filter.

Aaron B. <aaron at zadzmo.org>

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