----- Original Message -----From: John LoffinkSent: Tuesday, February 19, 2002 9:12 PMSubject: RE: [motm] QuantizingShort answer, no.
Long answer:
The miniwave uses a DAC0800LCN. Full scale error is +-1 Least Significant Bit and nonlinearity is 0.19%. Just looking at the nonlinearity, 0.19% of 10 volts, or the full scale Miniwave output, is 19 millivolts. 1 volt = 1 octave, 1 semitone = 1/12 = 83 millivolts, and 1 cent = 83mV/100 = .83 mV. ; 19mV/.83mV = 22.9 cents. So that\u2019s the accuracy you can expect from the Miniwave. You may get better results, but that\u2019s not guaranteed.
Pitch discrimination varies on the context. For monophonic lines you may only be able to discern 3-8 cents of pitch resolution. For chords, where you can hear the beating of the harmonies, pitch discrimination can be better than 1 cent, particularly if you\u2019re using a just tuning. For equal temperament, 1-2 cent accuracy is adequate.
As a comparison, the MOTM-300 VCO published specs correlate to a pitch accuracy of better than 1.4 cents from 50 Hz to 1600 Hz, and better than 4.4 cents from 25 Hz to 6400 Hz.
John Loffink
jloffink@austin.rr.com-----Original Message-----
From: sucrosemusic [mailto:sucrosemusic@...]
Sent: Monday, February 18, 2002 7:59 PM
To: motm@yahoogroups.com
Subject: [motm] Quantizing
Another thing I worry about (thought I don't have a miniwave) is the
relative low resolution of the 8-bit setup in the miniwave... is 255
levels enough to quanitize accurately, in a chromatic way? Or is it
just better for octave-octave-octave stuff? Just curious what your
experiences are, and, of course, if there are any "official" plans
for a quantizer. I agree that using a MV just for quantizing is
probably a waste.
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Message
Re: [motm] Quantizing
2002-02-20 by J. Larry Hendry
I have l long been thinking about a
quantizer. My thought process was that a very accurate circuit could be
built in the 8 bit format IF one used a ADC to get the digital quantities, but
avoided the 8 bit DAC by going completely analog on the output. Then each
of the 8 elements could be trimmed accuracy so when you added the elements each
together you would have much greater than the accuracy expected from a 8 bit
DAC. I can see Paul shaking his head and sighing at me right now.
But, I have been thinking seriously about a replacement for the 822 when
those PCBs are gone that uses pots instead of rotary switches. So, trimmer
count would be considerable less. Of course, then your basic circuit
is a quantizer. I have done no development yet because of other projects,
my need to learn more, and the (cough, cough) significant stock of 822 PCBs I
would like to make a dent in first. :) And, I fully admit to knowing
almost nothing about it and being significantly under-qualified for the
job. So, I'll probably play with it anyway.
On a related question, where would one normally
expect the analog out to track the input relative to step points. To
simplify the example, let's assume 1 volt steps. Would the output be
desired to change from 1 to 2 volts at 1.5 or 1.9999 on the input? I don't
see that is really matters. But, I am still pretty ignorant on the
subject.
Seems the 8 bit DAC might be fine for a mono synth
and single oscillator, but would never do where oscillators might beat
together. I have a couple of the PAiA 8 bit MIDI 2 CV 8s that I use
with stuff other than my MOTM modular. For my mono synths (like my
Micromoog) that 8 bit resolution seems to be OK.
Larry