Synth-diy-test

> On 5 Feb 2026, at 06:59, Richie Burnett <rburnett@richieburnett.co.uk> wrote:
> 
> TL071 op-amp dropped straight into the SH-09 and it works a treat.  One minute after releasing a note the pitch now only drops by about 15 cents. Not bad for an analogue sample & hold.
> 
> I also fixed the issue with the improvised sub-oscillator divider triggering on the wrong edge of the VCO waveform, (the PWM'ed edge,) which was imparting an annoying pitch warble on the sub-oscillator.  I made a little PCB with a 4013 dual D-type flip-flop chip on it to replace the original (missing and unobtainable) DN819 frequency dividers.  It sounds much better now.


Richie is this how all SH-09s behave, or was there a fault?
I can't recall mine warbling but because it's a sub, maybe I didn't notice...
A






> 
> Don Tillman you were right with your prediction of which edge that old I2L divider chip was clocked on! :-)  Many thanks.
> 
> -Richie,
> 
> 
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