In another topic we had @trumac22 chasing down the PWM/frequency interaction and reporting:
but I don’t think he was looking at the trailing edge glitches.
The Kassutronics 3340 design as of rev. 2.2 has this 10M resistor.:
On Rev 2.1 PCBs there may be some high-frequency oscillations around the pulse waveform transitions. While these oscillations are not directly audible, they can have an effect when using the pulse output as sync or clock source for other modules. To fix this issue, it is recommended to solder a 10M resistor directly between pins 4 and 5 of U2…
The T. Henry VCO Maximus has a resistor there but it’s 1M.