Nope, this is a mistake by PPCB. It seems to be the result of misreading the schematic of the original trace. If you look at the SFT V2 thread, the schematic shows R4, the voltage-divider resistor from Q2's gate, crossing this path but not intersecting it. The PCB photos in that same post don't show a resistor at Q1's gate.icziko wrote: ↑18 Nov 2020, 17:33 Add 1M resistor between Q1 gate and GND. This is missing component on schematics.
This is on pedalpcb schematics https://www.pedalpcb.com/docs/SOFTii.pdf
With this pedal works consistently, there is no need to "reset" it after each 10 seconds, tone is not dark anymore and different transistors can be used. I tried 2SK170, BF256B, J201 and 2N5457 and they were all consistent.
It'll still work with the resistor at the Q1 gate, but of all the other Catalinbread pedals that use the cascaded mu-amp topology, only the Formula #5 (V1 and V2) have a gate resistor on the JFET.
I've got an SFT V2 on the way so I can verify it myself, as I'm experiencing the same oscillation that's been described elsewhere. I think there's an error elsewhere in the schematic from that thread, likely around Q5. But based on the photos that have been shared, Q1 does not have a gate-to-ground resistor.
