Tube Amp Pop and Squeal

D

dirtythermos

New member
Last night my Boogie started popping randomly, really loudly. I quit using it, thinking I would try and diagnose the problem today. Today I turned it on, and as soon as I took it off standby, it squealed really loudly. It's not guitar feedback, it was coming from the amp.

I was looking at the tubes at the time and did not see any arcing, but there is something very wrong.

What should I do? I have a new set of preamp tubes I could try, but unfortunately don't have any power amp tubes. Do I have to replace the whole set, or if there is just 1 bad tube can I replace it? How would I find the bad tube? There is one power tube that glows a little brighter than the others, but that's about all I can see.

BTW, amp and tubes are Mesa, so I don't need to worry about bias. I know, I know, Mesa amps are biased cold and Mesa tubes suck. However, I like the "factory" sound of my amp and don't really want to experiment with it.
 
Maybe not. Pull all the preamp tubes, see if it still happens. If it stops, put the old ones back in starting farthest away from the input jack, and this should tell you which one is bad.
 
Yeah, that's a bit of a strange problem to occur, especially if this is a newer amp. I assume you've already made sure all the tubes are in place properly and none have been jarred loose? My first suggestion would be to just remove them all and reinsert just to be sure that's not the issue. But yeah, using Boing's method should help you locate the problem tube if that's the case.
 
I fixed it. The 2nd tube from the input was bad. The amp is about 6 years old.

I went ahead and replaced all the preamp tubes, because I figure that if one failed the others are close. However, I saved the good ones in case I need them later.
 
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