[sdiy] GRP Genesi

[Mike Bryant]

Actually one of the cleverest bits is probably converting the down-scaled squarewaves to sawtooths whilst keeping the levels consistent across the whole frequency range.  No mention of how they did they - presumably by programming a constant current source with the key and octave number ?
________________________________
From: Synth-diy <synth-diy-bounces at synth-diy.org> on behalf of Roman Sowa via Synth-diy <synth-diy at synth-diy.org>
Sent: 06 July 2026 12:06
To: synth-diy at synth-diy.org <synth-diy at synth-diy.org>
Subject: Re: [sdiy] GRP Genesi

At first glimpse, just looking at block diagram, it looks like typical
PLL, but instead of phase comparator it uses F-to-V conversion and
voltage comparator. Same divider ratio is used in the feedback as in the
vaweform output, so the VCO works only within 1 octave while overall
output spans over many octaves.

Roman

W dniu 2026-07-05 o 11:26, Neil Johnson via Synth-diy pisze:
> Michael E Caloroso wrote:
>
>     US 3,930,429
>
>
> Don did a write-up of it here:
> https://till.com/articles/arp/patents.html#US03930429
> <https://till.com/articles/arp/patents.html#US03930429>
> Very weird architecture indeed!
>
> Neil
>
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