#1
I've not had to retube an amp before, so I'm not totally sure the signs of tubes going bad. I've had my Peavey Classic 30 for probably a few years now, though. The other day I thought I heard it make a noise while playing, and today it's been breaking up heavily when I play the lower strings somewhat hard, or certain frets (12th fret of low E).

I put an mp3 on my profile called "Shot Tube?" just a quick recording of various notes and some of them breaking up as described. It's actually breaking up progressively more since recording that.

In the back of the amp, from left to right are 4 large tubes and 3 smaller tubes. The first smaller tube appears to be less illuminated, but the tube is also oriented the opposite direction (Electro-Harmonix side is to me, other 2 have it away). Using a mirror, it looks less illuminated on the other side as well.

I've tried 2 different cords (plugged directly into the amp), and both channels and it's doing the same thing, though I have no other guitar to try. Does this sound like a tube problem, or could it be a speaker problem? I want to avoid taking it to a tech if I can, simply because of the expense. Could I successfully change the tubes myself?

I appreciate any help!

Thanks
#2
You can change tubes by yourself, but if you don't know what you're doing, it really might be a good idea to take it to a tech. Otherwise you could end up messing things up further, and having to pay a tech even more to clean up your mess.
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#3
Ooh, sound clips! Very useful. People should do this more often, it's much easier to diagnose things this way.

That doesn't sound like a tube dying. It sounds like an intermittent connection or arcing somewhere. It might be a preamp tube, but I've not heard a dying one sound like that.

Take all the tubes out, clean the pins, and put them back where they were. If that's no good, it might need to go to a tech.
#4
I agree. That is not the sound of a dying tube. It sounds like a bad connection. Check your cable, guitar and amp connections.
#5
I opened the back of my guitar and checked the connections, they all seemed fine, tightened down the 5-way switch, and tried playing again. Still the same problem, then it got really loud and staticy or whatever, and I turned the volume knob down on the guitar and it didn't stop, changed the channel on the amp and it didn't sound any different. I should have unplugged the guitar to see if that made a difference, but I didn't think to, though everything on the guitar seems solid.

If I'm going to take out the tubes and clean the pins, do I need to avoid touching the tubes with my bare hands?
#6
Took the tubes out, checked the pins, they looked fine but I wiped them off, and where they are inserted looked fine too. The first 12AX7 from the left is an Electro-Harmonix, but all the other tubes in the amp are JJs - seems strange to me.

It's still doing the same. When it first comes on, it sounds fine and normal, then the breaking up starts happening, till it gets to be just breaking up noise, even with the guitar unplugged. I guess I'm going to have to take it to a tech tomorrow :/
#7
Quote by I Poke Badgers
Took the tubes out, checked the pins, they looked fine but I wiped them off, and where they are inserted looked fine too. The first 12AX7 from the left is an Electro-Harmonix, but all the other tubes in the amp are JJs - seems strange to me.

It's still doing the same. When it first comes on, it sounds fine and normal, then the breaking up starts happening, till it gets to be just breaking up noise, even with the guitar unplugged. I guess I'm going to have to take it to a tech tomorrow :/

Not at all, people mix and match preamp tubes all the time.
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#8
Quote by I Poke Badgers
Took the tubes out, checked the pins, they looked fine but I wiped them off, and where they are inserted looked fine too. The first 12AX7 from the left is an Electro-Harmonix, but all the other tubes in the amp are JJs - seems strange to me.

It's still doing the same. When it first comes on, it sounds fine and normal, then the breaking up starts happening, till it gets to be just breaking up noise, even with the guitar unplugged. I guess I'm going to have to take it to a tech tomorrow :/

That narrows it down a lot. You've got a part heating up and coming loose. You'll need to get a tech to track it down, but the good news is that it shouldn't be too expensive to fix and there's nothing further wrong with the amp.
#9
Had no internet for a while there thanks to lightning, but wanted to update this thread so if someone has a similar problem maybe they'll find it, or if you guys are curious the result.

Took the amp to my usual guitar store, and over the phone how I described it the guy thought it was just tubes going bad, but I made sure to show him the exact problem and once he heard it he said he'd never heard such a thing happen, so it went to their other location, they have an amp-tech that I guess does warranty work for Peavey, etc.

Anyway, what I was told is that some soldering inside the amp (not sure soldering of what) had come apart or something, so when it would heat up, it was coming loose and causing the sound to freak out, so the guy resoldered it all. (cost $35 (I'm sure soldering is not that difficult, but I'd rather not be opening up the amp myself and fooling around with that, with 0 soldering experience))

Played it a decent bit today and had no problems with the sound at all, so I believe all is well, tho I suppose I'll need to eventually replace my tubes as they're like 4 years old. But, that's for another day when I have money!

Thanks for all the help and advice guys! Glad it went to the shop instead of me replacing the tubes only to find out that wasn't the problem.