[sdiy] Quantizer DAC or PWM?

[Tom Wiltshire]

Scott Rider's example shows how the same idea can be used with a uP and a Dual DAC.

For V/Oct, you'd have separate DAC channels for the 1V octaves and the 83mV notes, and then add them together. The PWM DAC I mentioned earlier in the thread is an example of this approach.

For V/Hz, you'd use one DAC to produce the reference voltage for the other (as in Scott R's CS15 example). In both cases, you're using two lower resolution DACs to avoid the need for one high resolution DAC. Of course, it's always possible to do whatever we like if we've got 16-bit DACs for everything, but the fun part is doing the same job with a cheap 8-bit DAC and *still* getting it to work!


> On 20 Dec 2022, at 12:42, Mattias Rickardsson <mr at analogue.org> wrote:
> 
> But isn't this structure more of an old "mechanical" solution, rather than a microcontroller solution of today? :-)
> 
> /mr
> 
> 
> Den tis 20 dec. 2022 13:15Tom Wiltshire <tom at electricdruid.net <mailto:tom at electricdruid.net>> skrev:
> The Moog Taurus is another example of this structure.
> 
> Tom
> 
> > On 20 Dec 2022, at 11:50, Roman Sowa <modular at go2.pl <mailto:modular at go2.pl>> wrote:
> > 
> > Separate Octave and semitone resistor ladders with muxes selecting them was the heart of (all?) Yamaha CS-series keyboard controllers.
> > 
> > Roman
> > 
> > W dniu 2022-12-20 o 12:41, Florian Anwander pisze:
> >> Hi
> >> Am 19.12.22 um 22:54 schrieb Didier Leplae via Synth-diy:
> >>> Ah yes, a separate output for octaves is brilliant!
> >> btw Scott rider aka Old Crow used a similar trick to achieve Hz/V characteristics with an 8Bit:
> >> https://github.com/cs80/CS15_SSK/ <https://github.com/cs80/CS15_SSK/>
> >> He uses a dual channel DAC MCP4922. DAC #1 is providing different reference voltages for each octave, which then are used by the DAC #2 which converts the same twelve note data to a spreading CV the higher the octave / refence voltage from DAC#1 respectively is.
> >> Florian
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