Bias changing with PPIMV settings

[Cless357]

Hi, I have a Ceriatone plexi clone, with a Lar-Mar PPIMV. It's a 220k double pot (theorically, in reality one pot is 200k and the other one 240k, so in the -10%/+10% tolerance).
I checked the bias at bedroom volume, it was around 30-33 mA for al power tubes (Ceriatone advises 35mA for 65% dissipation). So I cranked the PPIMV (I think the bias should be adjusted with the PPIMV maxed ?) and I see that it is now 35-36mA for 2 power tubes and 45-47mA for the 2 other ones !!!
Is it because of the tolerances of the two pots of the PPIMV ? So what bias should I aim ?

 

[311splawndude]

I'm not the right guy for this but since I took the time to read this and try to understand I will only make a few comments:

1. Generally, a plexi type amp on EL34s will hit the sweet spot around 35% mA.
2. That however depends on the plate voltage. What is your plate voltage?
3. Every amp tech I've spoke to says do NOT play through your amp to read and adjust bias.
4. I put the volume on zero and unplug the guitar when I bias my plexi style amp.
5. Can't speak to Ceriatone as I've never owned one, but if you pull two power tubes then you are running at half power and should therefore drop your output ohms in half and I would not expect the MV pots to affect the bias, but since you are cranking to volume - I have no clue.

tl;dr - sorry you are having trouble, hope you get it resolved, and bias with no signal going through amp