[sdiy] VCO that goes SHARP in highest octaves??

Maarten Halmans diy at artefacts.nl
Thu Jun 16 08:48:01 CEST 2022


Hello Neil,

Are you sure the problem is in the higher octaves, didn't you compensate 
for a problem on the low end resulting in the oscillator going sharp in 
the higher octaves? I had this twice with a Jupiter-8 oscillator, once 
it was caused by flux and the other time by a leaky FET.

Best,

Maarten

Op 16-6-2022 om 03:37 schreef Neil Harper via Synth-diy:
>
>
> On 6/15/22 21:04, Mike Bryant wrote:
>> I can't remember the original details or the circuit, but have you 
>> tried replacing whatever creates the exponential conversion ?    It 
>> may be the gain of it changes at higher input voltages more than any 
>> correction circuitry allows for.
>
> hi Mike,
> pretty much the last thing I haven't swapped out are the opamps,
> LM137000 and the matched pair transistors. At this point I've just
> accepted that there's a +10-20cent error at C8, because the transistor
> pair SMT package I used is VERY small and I can't picture being able to
> remove it and tack on some regular handmatched TH transistors to see if
> that fixes the issue..
>
>
>
>
> -- 
> /// Neil Harper
> /// Every Wave is New Until it Breaks
>
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