If you change to a different brand of el34 in a Marshall jmp, do you need to rebias

[martyhk0]

I know, its a noob question.

[Blue Fin]

I think that the answer is yes.

[Groovey Records]

You must at least check the bias, if you have a well matched pair you may be good to go. Still even then adjustment may be required!

Groovey Records
enjoy the music

[stuagu]

definately needs checking.

[Blue Strat]

Yes, even a pair of the same brand of tubes requires checking/adjusting.