9V BBD Flanger Layout problem/question with video of issue

[DrAlx]

Just searched through your thread on the strip down. The schematic you posted there has direct BBD connection:
https://postimg.cc/yJp7Xwmr

So you made an error combining the three board schematics into a single schematic and that error is also in your layouts.

Since your BBD input now picks up stuff on the circuit output, any switching noise at the output (e.g. from plugging you pedal into a device that switches) will get fed to the BBD input and give heterodyning. Before you try any other soldering, stick a buffer between the pedal and your class D amp and see if that reduces the level of the whistle.

[bushidov]

CRAP!!!! You found it! I cut the trace on my layout that directly connected the BBD pin 3 to between R10 and C6 and then ran a new trace wire from BBD pin 3 to the U1B op amp pin 7 and now it's perfect!

Apparently, I fat fingered that while making the new layout.

Thanks again!

[DrAlx]

Good.

... and one other thing.  My suggested mod of adding 1k2 and 3n3 LPF after the 2N3904 needs to be done in addition to leaving the 680pF where it is on the left of the 2N3904.  It should not be a replacement for it.  My mistake.

[bushidov]

Cool beans. I sent you a PM, if you get a chance to reply.

[j_flanders]

There is one thing I just noticed about your schematic vs the EM3207. Your BBD input in the schematic is not connected directly to U1B pin 7. It is on the wrong side of R10.  So your BBD input is only separated from the circuit output by a cap rather than by R10 and the cap.

Pretty incredible! Well spotted.