Trouble in paradise - great sound lost - HELP

[gsx777]

Just recently I noticed a major change in tone happening with the Mark V. It started out a an inconsistent tone and now it just sux. I had a great sound 2 weeks ago when I recorded a demo http://soundcloud.com/greg-spack/mesa-demo, but then shortly after the problems began...
The sound I am getting now is most noticed on channels 2 & 3 with more gain. The sound is thin and swauky, almost like having a wah left half cocked, it lacks the fullness and bottom it once had, kinda like an 8 inch solid state combo...yuk! Any Suggestions? Please.
Also... I tried various guitars and cables

Thanx.... Greg

 

[satch4u3]

I haven't had this issue myself in the two years I have had this amp. But from what I have read on this forum it always seem to lead towards a tube issue. Mainly preamp tubes.

 

[gsx777]

Ok, So it was V2 and V3 that were bad.... Go figure! I figured no way it was that easy, but sure enough, I replaced them and the UMPH is back!

 

[search4tone]

Thanks for posting your problem and solution. Now if I can just remember to look here if it happens to me.

 

[screamingdaisy]

It's nice when a problem is easily solved.