[sdiy] 2164 gain response variability

[cheater cheater]

What about the SSM2164's, as opposed to the Cool Audio V2164? How do
they respond?

Cheers
D.

On Sun, Apr 18, 2010 at 23:27, David G. Dixon <dixon at interchange.ubc.ca> wrote:
> Well, I finally completed two identical 2164 Expo VCOs with all the little
> improvements, and I can now say that there is indeed a little bit of
> variability in the gain response of different V2164 chips.
>
> Also, the gain response is not perfectly linear, but typically dips a little
> bit at 0V.  In fact, the tracking response looks a bit like a seagull in
> flight.  Hence, setting 1000Hz as the reference frequency at 0V CV and
> adjusting to exactly 125Hz at -3V, then 250 and 500Hz are a little bit high
> (0.2 to 0.5Hz), and 62.5Hz is a tad low (0.2Hz).  Likewise, pulling up to
> exactly 4000Hz at 2V with HF trim, then 2000Hz may be 1 or 2Hz high, and
> 8000Hz may be a few Hz low.  Tuning tends to be a bit of a compromise
> between the low and high ranges.
>
> In any case, if two reasonably similar chips are selected, then the two VCOs
> can be tuned almost identically up to the top of the useful range, and they
> are pretty stable.  In fact, my two VCOs sound absolutely stunning together!
> If unmatched chips are selected, then the frequencies might differ by 2 or 3
> Hz in the 1000 to 4000Hz range when the lower frequencies are optimally
> tuned.
>
> Also, the occasional 2164 chip even has an "upside-down seagull" response.
> I'll try to reserve these for use in VCFs or VCAs.
>
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