[sdiy] GRP Genesi

[Donald Tillman]

Yeah, building a sawtooth wave by summing the square waves from the higher divide-down octaves was standard practice for many electronic organs back in the day.  The Schober organs for sure.  

There are fewer octaves to sum on the higher notes, sure, but that's okay.

  -- Don
--
Donald Tillman, Palo Alto, California
https://till.com

> On Jul 6, 2026, at 3:25 PM, Tom Wiltshire <tom at electricdruid.net> wrote:
> 
> Isn't it just the typical adding-up-a-load-of-octave-squarewaves to make a staircase "ramp" waveform? 6 bits in this case, iirc.
> 
> Ah, yes, here it is, from the service manual:
> 
> 
>> On 6 Jul 2026, at 13:01, Mike Bryant <mbryant at futurehorizons.com> wrote:
>> 
>> 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.