[sdiy] YuSynth vco tracking

[blacet at blacet.com]

What might be handy is a "final correction" circuit that adds or subtracts
a tiny bit of CV depending on the octave you are playing in.

An inexpensive uC could read the main CV and/or check the frequency out,
appying a small correction voltage it has placed in it's memory. Since the
voltage would be very small, only a cheap DA would be necessary. Even
using on board AD to perform pluse width style DA might  be OK.


> I was just reading some web forum entries which led me to the YuSynth VCO
> page.  According to the instructions for tracking adjustment, one is to
> set
> the pitch at 55Hz at CV = 0V, then adjust T2 (the CV summer gain trim)
> until
> the pitch is 110Hz at CV = 1V.  OK.  Then, it says to repeat this
> procedure
> all the way up to CV = 6 or 7V (presumably from 0V every time).
>
> What does this achieve?  Why would one make six or seven adjustments to
> the
> same trimmer?  Unless the overall tracking is perfect, won't this only
> ensure optimum tracking at the last octave adjusted?  In other words, if
> one
> has to make changes to the trimmer after perfecting the first (one octave)
> adjustment, then won't that first octave be off?  Is this procedure
> designed
> to give the best "average" tracking?
>
> I don't get it.
>
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