[sdiy] Quantizer DAC or PWM?

Tom Wiltshire tom at electricdruid.net
Mon Dec 19 18:20:47 CET 2022

If you're quantising, you actually *want* a stepped voltage output, so the required resolution can be very low.

I designed a Eurorack quantizer module for Frequency Central that used two PWM channels for the output. IIRC, both channels were set up as 4-bit PWM, so the output frequency was very high and the smoothing could be very good, but still have a quick response to CV changes.
One channel was scaled to produce 1V steps, and we used only 9 or 10 of the available levels. The other produced Note CVs across a single octave, so we used only 12 of the 16 available steps. Adding the two together, we could rapidly produce Pitch CV's across wide range with good linearity and very low cost.

So my view is that the DAC is a luxury, if all you need is notes.


> On 19 Dec 2022, at 16:10, Didier Leplae via Synth-diy <synth-diy at synth-diy.org> wrote:
> I’m working on developing a quantizer module for eurorack. I made a previous version using a PIC chip with a DAC which I abandoned during the chip shortage.
> Now I’m looking at taking up the project again but possibly with an esp32-s3 chip instead. This chip only has PWM, though.
> Question is whether PWM with smoothing circuit is it accurate enough for a quantizer? Does anyone have smoothing circuit to recommend?
> Or is a DAC the better option?
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