Amp(s) losing power

[tommy p]

As I was playing at practice last week, my Mesa Nomad 55 seemed to be losing power after an hour or two of playing. I turned it off for a while and it worked OK for a few minutes when we started up again but then started cutting out, sounding weak again. I figured I would check the tubes but didn't get around to it before practice tonight.

I took my Peavey Classic 30 out tonight and the same exact thing happened. An hour or an hour and a half in, it starts sounding weak, like it's losing power.

The commonalities are the guitar I used, the cables, and the pedalboard. Is it possible that some pedal is dying? I use them very sparingly and didn't have any on either time when this started happening. I checked all my connections and they seemed good, but I haven't used a cable tester yet.

[HSB0531]

Try a different wall outlet.

Does it happen when everyone else is cranking loud?

If you're all on the same circuit this could be it.

But since you tried 2 different amps, it's probably a weak, near dead battery in a pedal.

Try playing directly into the amp for a while.

[tommy p]

Try a different wall outlet.

Does it happen when everyone else is cranking loud?

If you're all on the same circuit this could be it.

But since you tried 2 different amps, it's probably a weak, near dead battery in a pedal.

Try playing directly into the amp for a while.

Thanks for the suggestions.

It's the drummer's house, so I'm not sure if we're all on the same circuit. I know he had an electrician friend who's also a guitarist set up the room we play in, but that doesn't answer the question.

Some extra info: I'm not running wireless, and my pedals are all in a powered board so no batteries.

[HSB0531]

Could be one of the DC power chords from the board to an Efx pedal.

Was the electrician a journeyman or a gofer

[Brewmaster]

I need to address the obvious here. When was the last time you changed the tubes in both amps? Yeah, I know, when this happens in two amps in one night what are the odds it's a tube or two in each amp, so tubes are the last thing you would look at. You would be amazed.

I had one of my customers with a similar issue last year. Both his main amp and backup failed on the same night. He came to me in a panic. Turned out one amp had a bad preamp tube and the other needed power tubes.

[whiskeyzulu]

Can we assume that you have played the amp w/ same set up and same amount of time at your own house or other venue w/o the sag problem - correct?

If not, it strikes me as odd that after 1.5 hrs of play, the culprit would be the house circuitry - if there was something goofy w/ wiring it should effect amp right away. I would venture to guess that its either one of your pedals overheating (do you have any tube driven OD pedals) or, coincidentally, old tubes in both amps - which, although unlikely is a plausible explanation. I had an amp that seemed to get "tired" after 1.5 -2 hrs of playing swapped tubes and problem solved.

I'd play the amp straight w/o any pedals for the same amount of time and see if the problem re-occurs, if yes time for new tubes, if not its one of your pedals and then systematically add them back into the chain.