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Author Simple chromatic quantizer code
sbmani
 Anyone have experience with code for quantizers? Pardon if this is stupid - but is there any pure analog way to do it? There was a thread on the Euro forum about a guy asking for a simple quad chromatic quantizer and Id like to try my hand at building one
MapacheRaper
 In this case digital is your friend. You can do it in analog too but is a bitch to do it right, while in digital (arduino, for example) is pretty much straightforward. Just look for arduino quantizer, theres a lot of implementations out there
jorg
 I applaud your effort; I have dabbled some with that notion. I think there should be an analog way to do it. Actually, if it's only chromatic, it's fairly straightforward. First, a string of comparators fed by a string of resistors for the thresholds; space them by 1V. Take the resulting octave value, and subtract it from the input voltage. Then you have a 2nd string of resistors and comparators, spaced by 1/12 of a volt. To get the ocatave voltage from the first string, or note voltage from the 2nd string, sum all the comparator outputs with an op amp and an equal-valued resistor from each comparator to the summing node of the op amp. Final output is the sum of the octave voltage and the note voltage. Obviously, you want to use precision op amps and resistors here. Comparators should be a rail-to-rail output device, powered by accurately regulated supply. The next thing I'd like to figure is how to do this for an arbitrary scale, yet have equal-spaced voltages on the input, corresponding to the irregular spaced quantized values on the output. I've figured it out in a digital simulation; I think it should be doable in analog. That would be KILLER.
sbmani
 Thanks for the suggestions! Nice explanation jorg, I am gonna poke around for some analog schematics too. But that actually seems doable with precision trimmers
guest
 ultimately, you will be making an ADDAC system either way, and the ADCs and DACs out there are pretty cheap and very good. if you dont want to program, you can use a parallel 8b ADC with an R/2R DAC at the output. there are also variants on this: this was for a VCO, but it is similar. at the core is a comparator that looks at the DAC value and incoming value, and increments a counter if it is above or below. you would need some hysteresis in that comparator, and use up/down counters with pulse generators (so it automatically increments, in the above schematic it relies on the sawtooth way to increment).
 jorg wrote: I applaud your effort; I have dabbled some with that notion. I think there should be an analog way to do it. Actually, if it's only chromatic, it's fairly straightforward. First, a string of comparators fed by a string of resistors for the thresholds; space them by 1V. Take the resulting octave value, and subtract it from the input voltage. Then you have a 2nd string of resistors and comparators, spaced by 1/12 of a volt. To get the ocatave voltage from the first string, or note voltage from the 2nd string, sum all the comparator outputs with an op amp and an equal-valued resistor from each comparator to the summing node of the op amp. Final output is the sum of the octave voltage and the note voltage. Obviously, you want to use precision op amps and resistors here. Comparators should be a rail-to-rail output device, powered by accurately regulated supply. The next thing I'd like to figure is how to do this for an arbitrary scale, yet have equal-spaced voltages on the input, corresponding to the irregular spaced quantized values on the output. I've figured it out in a digital simulation; I think it should be doable in analog. That would be KILLER.

That's a very cool solution, but it sounds like you'd be stuck in 12et. I'd rather go digital and be able to tune the thing however I choose.
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