I need some of your expert advice people.

Amp started motoboating/ sputtering, replaced power tubes, no issues for approx 1 hour, has lost power, it gives me a very weak signal-sound,(volume)  not even close to what it was b4.

I have numerous matched sets of tubes, pre and power tubes. Good connections, good power good speaker cab, all verified with other guitars-cables-cabinets-etc..

Same problem

What thinks u people? Thanks for any help

Peace
Steve

Hey thanks for the reply M

I am an expierenced player, but have not done too much techy stuff.

It was my understanding that if I used a matched set, with the same values as the original tubes from Nik, that re-biasing was not needed, since there is no bias pot on this model.

If it's not too much trouble could you please enlighten me, I don't know if I will do the work, I am just trying to get my head around this issue!

The circuit seems simple enough for me to at least narrow down the problem.

Anyway no worries Nik is on the job just wanted some opinons from expierenced builders.

Thanks
Steve