Threshold Pot doesn't work

[h9361]

Show me your schematic.

[Carl-NC]

I don't know exactly how the GPX sounds, but if you want to slow down Q17 try increasing R75 to maybe 100k. You can also add a parallel cap to ground, try different values. A big problem with this is that Q17 is NPN and will tend to turn off quickly due to the high gm-RL gain. An NMOS might behave better.

Also, you are missing the load resistors; R27 and R31 in post 585. Those are critical.

[h9361]

I don't know exactly how the GPX sounds, but if you want to slow down Q17 try increasing R75 to maybe 100k. You can also add a parallel cap to ground, try different values. A big problem with this is that Q17 is NPN and will tend to turn off quickly due to the high gm-RL gain. An NMOS might behave better.

Also, you are missing the load resistors; R27 and R31 in post 585. Those are critical.

Thanks.
Please watch the gpx iron rejection,

https://youtu.be/WlMXWP_TVN4?is=nCdxAJsJhs8t2bKO

I added the parallel capacitor and nmos. Please check nmos pins S and D is true?
Do you have any value suggestion for the parallel capacitor?

[Carl-NC]

D & S are backward. Sorry, I don't know how to make it sound like a GPX.

[h9361]

D & S are backward. Sorry, I don't know how to make it sound like a GPX.

Thanks.
Do you have any suggestion value for the parallel capacitor (red circle)?

[Carl-NC]

No, you'll have to experiment with it.