[sdiy] Transistor questions

[Roman Sowa]

That's interesting twist.
OTOH I never heard anyone complain about messy triangle in their PS3xxx 
or 700, or 800DV or I don't know where else triangle sctacking was used.
Maybe that's the part of their unique sound?

I'm not a big fan of making 100% replica of old synths, so if you're 
making quite a few changes to take advantage of today's possibilities, 
you get my vote for DIY project of the year.

Roman

W dniu 2025-03-03 o 21:07, David G Dixon pisze:
>   
> Yes, Roman, but I'm doing my version a little bit differently.  My octave
> selector will add 1V increments to the VCO CV circuits, so they will need to
> track more or less perfectly over four octaves up to about 6kHz.
> 
>>From what I can gather from the original schematic, and from Jurgen Haible's
> PS-3200 build, the original octave selector routes the signal from divided
> down versions, but I must confess that I didn't really understand how this
> was achieved in the original (as it would require that each saw generates 7
> octaves, and the slowest ones will look very messy, with all of those steps
> and shifts).  Hence, I opted only to generate 4 octaves from each saw, and
> use CV to shift octaves on the front panel.
> 
> In fact, there are a lot of things in the original circuit that I didn't
> understand, and couldn't get to make any meaningful results in simulation.
> If I can't simulate it, then I don't build it -- it's just that simple.  So
> I'm relying on my own circuits for many of the bits and pieces, and opting
> to use ICs for the bigger chunks (AS3310 for envelopes -- there will be two
> complete ADSRs per key -- and AS3350 for filters -- unlike the original,
> these will have fadeable multimode outputs) to save PCB space -- I got the
> chips at a significant discount.
> 
> 
> -----Original Message-----
> From: Roman Sowa [mailto:modular at go2.pl]
> 
> But anyway, here's a thought - arent PS3100 VCOs tuned at basicaly
> constant frequency, varied only in small amount by LFOs and pitchbend?
> Even if it's +/-2 octaves, I don't see any need for super precise tuning
> scale to start with.
> 
> Roman
>