Dual 3ch Rectifier sound problem

[Raggi73]

My mesa dual rectifier 3ch (model: 2007) is making a disturbing noise after playing for a while.
Difficult to describe the sound, but it sound distorted/electrical and it disappear after I turn off the stand-by.
I could maybe describe the sound as a really small-cheap amp that you crank all the dials to 120% and ad a little overdrive/distortion. Really bad distortion!!

I often use my 3. channel on modern settings as we play Metal-type music and this is where I encounter this sound/failure
I did change all of the tubes a few months back to JJ electronics (6L6) (also the small ones) and Mesa for the two on the far right side.
To me this probably could be the tubes, right? I have the originals as spare and have put them back into the amp, but haven’t tried it long enough yet. ALSO, the originals sound much better as well. Much tighter sound.

I believe I bought these JJ tubes one by one and not as paired. As the Mesa don't have Bias, could this degrade the sound of the JJ or even damage them?

 

[kruzty]

You definitely need matched power tubes. You can probably get by with matched pairs for the two inner and two outer power tubes, but as you noted there is no bias, so you should probably stick with the mesa tubes.

I can't say if that is causing all of the problems you are noticing, but the lack of tightness you mentioned is a sure sign of it.

Since the "bad sound" problem occurs only on the modern voicing, that may be a bad pre-amp tube. You should check the manual, but I think V2 or V3 would be the place to start. Just swap them (one at a time so you can pinpoint the bad tube) with an extra 12ax7 and see if the problem goes away.

 

[Raggi73]

Yessss. Went back to my original Mesa tubes (all of them) and played a great gigg this friday with a kick-*** sound. My clean and distotion sound waaayyyy better. Next time: Buying all Mesa tubes.