Ampeg SVT VR tone has gone brighter - brittle treble

[EASonBass]

Yes, I'll take it to a tech . . . but curious if the collective wisdom might shed some light on why an '05 VR tone might have suddenly gone to a brittle, distorted treble that can't be tamed.

I'd normally run the treble up a little like at 1 o'clock, now I'm cutting to 9 and its still bright and distorted. Still has a strong low end you can feel but with a distorted treble over the top through a standard 'fridge. Could it be related to the speakers?

[JimmyM]

I was thinking a bad tube. Does it sound like that in channel 2 as well?

[Seans]

Maybe try swapping the like pre amp tubes around.

[KLEIN]

I agree with Jimmy. Might be a bad tube, orcould be a bad treble pot.

[EASonBass]

Originally Posted by JimmyM

I was thinking a bad tube. Does it sound like that in channel 2 as well?

Uh, didn't think of trying that . . .

Thanks for the suggestions guys.

[kranahan]

It's a preamp or driver tube most likely. Same thing happened to me and it ended up being a bad driver tube.

[EASonBass]

Ok, finally in one spot long enough to get the amp to a tech. Turned out to be a bad solder joint on the preamp board associated with the treble pot. It would manifest itself from the mechanical vibrations of the head on the cab.

Tech re-flowed all the pots and such on the PCB for me while he was in there.

Tubes all A-OK.

Props to Armen at Ampwerx for fast, clean work!

[JimmyM]

Well now you know why I'm not a tech

[Foz]

'cause you're too busy saving souls?

[JimmyM]

Ya, that's it, Foz.