Grounding the presence pot

[dude]

Does it make any difference if the presence pot in an amp is grounded to the preamp side or the HV side? I usually add the ground to the buss bar that is grounded at the preamp ground only. Never had an issue.
On the PCB in the Blues Junior, no presence pot but the negative feedback is grounded directly to the filters on the HV side. I added a presence pot to the BJ, wiring exactly as a 6v6 Plexi, l’m having an issue with sizzle (like bacon frying) and after playing the amp (hot), then comes terrible distortion noises, that aren’ there at first.
I have the PCB board hanging while l play trying to find the cause. I just want to “rule out anything in the added presence circuit” l added before l look else where. I recheck my wiring to the presence pot and 99% it’s correct, except the ground is going direct to the HV caps, where the Plexi goes to preamp side.
Also, if l pull the PI tube the sizzle is gone. So, l’m thinking it’s something connected to that tube, like the presence pot l added.

[sluckey]

Does it make any difference if the presence pot in an amp is grounded to the preamp side or the HV side? I usually add the ground to the buss bar that is grounded at the preamp ground only.

Since the pot connects to the cathode of the PI and the PI is usually considered part of the power amp, the grounds keeper would probably say ground it with the power grounds. However, I've seen it successfully done both ways.

[dude]

Ok, that’s the way it is in the BJ, l did it the other way in my 6v6 Plexi, same as you on the buss grounded at the preamp side, only.
Now on to fix my issue, quite an experience working on a difficult PCB board but definitely a learning experience in reading schematics, a good thing. I’ll figure out the issue and it’s ten times as hard as diagnosing PTP board.
Good possibility it’s a cold joint, as the amp plays till it gets hot, the bacon frying may be the same issue as the bad noises or two issues. But pulling the PI tube, the sizzle stops. I’m look for cold joints at that tube pins, tried different tubes, all of them, and points on the board. I can play the amp during each fix. Noises may be the plate R’s too but did they just decide to go after the presence change, did l do something wrong in the change..? Possibly, l will disconnect the presence, try.  Makes sense about the presence ground as it’s in the PI, thanks 

[dude]

Sizzle gone, bad distortion gone. Presence pot works well but with the vintage presence wiring there’s low voltage on the pot but who cares, who’s turning the pot when playing. Not sure what the issue was but l washed the board, tiny solder flicks around were l did BillM mods and re-flowed anything that had a hint of being weak. I did find a lifted pad halfway but was making continuity first time, his time l fixed, maybe was the issue..?
I’m kind of glad his happened as having only to go by the schematic, forced me to sharpen my schematic reading ability.

[sluckey]

Presence pot works well but with the vintage presence wiring there’s low voltage on the pot but who cares, who’s turning the pot when playing.

Just the way it is. That's normal.

forced me to sharpen my schematic reading ability.

And that's a good thing. Keep it up.