hey guys, my block letter 5150 will randomly decide to get really quiet. usually i'll be playing a show with the volume up to 3-4, then when it goes quiet, i can crank it and still cant be heard. some volume comes through, but it sounds like complete shit. when i bought it, the dude said it was just retubed not long ago. any help is appreciated.
how do i fix something like this? my band has a few shows coming up and i need this fixed asap.
this is my first tube head. i dont know much about them. is there a walk through online available?
Depends on how much you want to spend - on the cheap end, you're still looking at about $60-70 for a matched quad of 6L6 power tubes.

As for the latter part of your post... How long have you had the amp? If it was recently retubed and you haven't been playing it hard or playing for a long time, it's possible that something else is causing the tubes to fail.
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I dont know exactly how long since the head was retubed. He couldn't answer me with that. But I play it maybe 2 times a week for 3-4 hours. Could it be because they aren't a matched set?
I have a 5150 212 combo and I'm having the exact same problem. I had my tubes tested and they were all OK. Don't just go out and buy tubes without figuring out what the problem is. I still haven't figured it out.
Ibanez RGR421EXFM >> Maxon OD808 >> BOSS NS-2 >> Peavey 5150 212
i saw something on youtube about spraying connection cleaner into the inputs but im kinda sketchy on that.
Sounds like the effects loop to be honest.

It's a pretty common problem among 5150s, mine actually suffers from it.

Basically, the jacks in the effects loop get dirty causing a volume drop, and in my case, all the presence to disappear, so it looses all the crunch and sounds like mud.

It can sometimes be fixed just by shoving the jacks in and out which could clean them.

Mine's pretty advanced and I'm taking it into a tech to get cleaned properly cause I don't trust myself with electronics. When you consider that the newest a 5150 can be is 6-7 years old, it's not that surprising that some bits have gotten a bit dirty.

EDIT: Careful with the contact cleaner. The power amp board is directly below the FX loop jacks, so if you go a bit overboard you could be causing all sorts of much worse problems....
Guitars: PRS Custom 24, PRS EG3, PRS Santana SE, PRS Tremonti SE, ESP-LTD M-200FM

Acoustics: Maton EM225C, Washburn WD-42S, Ovation Tangent

Amps: Peavey 5150 Mk 1, Randall V2, Marshall JCM2000 DSL100

Cab: Framus FR212
thats what the youtube video was about. sounds pretty legitimate too. im gonna try that out to see how that works before i do anything.
I had a similar problem where the volume would drop to about half every once in a while. Turns out a tube in the power amp wasn't seated properly in the socket. I pulled it out then put it back in properly and I haven't had the problem since.
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