[sdiy] Quantizer project.. final choices with all that..

Jean-Pierre Desrochers jpdesroc at oricom.ca
Wed Jul 7 16:30:34 CEST 2021

After all these very technical talks & exchanges about scales and intervals
I think I’ll build my next quantizer in my ‘make it simple’ way.


*Using about the same hardware I used for my M114
>  CV/GATE delay 
   which has SPI 16 bits ADC/DAC’s but this time without SPI RAM. 
    It can support 0 to +8vdc IN/OUT CV’s.


*Using preformatted scale lookup tables (up to 100 of these)
  (rotary encoder/display  selectable)


*As David proposed, using “equal voltage intervals between each notes”
   (more musical and predictable CV output results)


*A separate 12 positions rotary switch for semitones transposing the CV
output results


*And finally a MIDI output that tracks with the selected CV scale outputs


This pleases me..


Thanks to all of you for sharing your precious knowledge !




De : David G Dixon [mailto:dixon at mail.ubc.ca] 
Envoyé : 5 juillet 2021 19:43
À : 'Jean-Pierre Desrochers'; 'SDIY'
Objet : RE: [sdiy] Quantizer project.. incoming CV's switching point to
change to quantized output CV's ...


I don't know diddly-squat about code, but I've been working on an analog
quantizer with logic for generating various scales, and I must say that I'm
a strong advocate of the "equal voltage invervals between each note"


Of course, for the chromatic scale, this is a no-brainer: 83.33 mV per note.
However, if you want to quantize a major triad, I would use 333.33 mV per
note.  For a major scale, 142.86 mV per note.  Et cetera.


Why?  Because if you are running the scales or arpeggios by playing the
quantizer with a triangle wave LFO, you will want each note to last for the
same amount of time.  Any other approach will impose a rhythm that will
favour notes that are farther away in pitch from the others.


As usual, the right answer is the musical one, not the technical one.



From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of
Jean-Pierre Desrochers
Sent: Sunday, July 04, 2021 10:35 AM
To: 'SDIY'
Subject: [sdiy] Quantizer project.. incoming CV's switching point to change
to quantized output CV's ...

[CAUTION: Non-UBC Email]

I'm starting a CV quantizer design and am wondering

about the following things:


Let's assume a normal quantized semi-tone scale:

All the incoming CV's are quantized to semi-tones like this:

incoming CV 'around' C, output quantized CV -> C

incoming CV 'around' C#, output quantized CV -> C#

incoming CV 'around' D, output quantized CV -> D

and so on..

12 equally spaced output quantized intervals. OK.


But if the quantized scale output is a TRIAD like

C-E-G-C-E-G-C, etc... ( 3 quantized intervals)


where are the switching bounderies of each incoming note CV's 

to change to the next outputed quantized note ?

This question is for ascending and/or descending notes..


Same question for a quantized PENTATONIC major scale output like

C-D#-F-G-A#-C-D#-F-G-A#-C, etc.. ( 5 quantized intervals)


I would think of dividing the octave range with 

equal intervals with the number of intervals

inside the actual quantized scale..

For example: 


That's 3 intervals

1 octave = 1 volt

so 1volt/3 intervals = 0.333v between each quantized notes (??)




PENTATONIC major scale C-D#-F-G-A#-C

That's 5 intervals

1 octave = 1 volt

so 1volt/5 intervals = 0.20v between each quantized notes (??)


But... I don't think that is working this way..

I think I must keep the incoming CV interval sizes

and use them for the quantized switch points.. (???)


Your opinion on that ??

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