Volume Drop Problem

[Nathan]

Hey all,

I have a Mesa Blue Angel that is plaguing me with the most annoying problem: volume will drop out after about 15 minutes of playing. I can get it back to normal by flipping the standby switch off then on again, sometimes it take s a few tries but invariably it drops out later. Any clue what could be causing this?

Pretty sure I have tried changing every tube at one point or another and haven't been able to solve this. All my preamp tubes were tested by a buddy recently and they check out fine. Took the amp to a tech who could not reproduce the problem of course... There almost seems to be a phase issue when the volume drops too. FWIW I use the 6V6 side almost exclusively. Cheers if you can help!

Regards

[shooter]

Any clue what could be causing this?

run it with the 6V6 til it quits, power down then switch to the '84s till it quits, or not.  That should eliminate 1/2 the PA.

I'd monitor the "A" tap on the ps and see if it starts drifting down with volume (VDC)

[jjasilli]

Checklist:  geofex.com > tube amp debug page > Low Power or Loss of Volume


Also use tubenit's posted checklists & flowcharts.

[tonepumpamps]

I've seen filter caps do some pretty strange things.  It could possibly be that.