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amp buzzes (peavey classic 30)

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(@anonymous)
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Joined: 17 years ago
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when i play above a certain volume, i get this annoying high pitched ghostly buzz. i checked the screws, and they're all machine tight and i can't even loosen them, so that's not it. the tubes seem to be seated well, although they run too hot to touch for more than a millisecond when it's on. i'm guessing it's the reverb tank. i tried to remove it, but i think it's held down with a screw that i can't get to without dismantling the cab, and i don't want to do that unless i know what the problem is. also, it'll be a pita, since i can't hand unscrew the screws anyway.
anyone with any experience on these?


   
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(@ricochet)
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Joined: 21 years ago
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How old are the tubes? Unpleasant distortion can be a sign of dying tubes.

"A cheerful heart is good medicine."


   
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(@anonymous)
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i think they're less than a year old. i bought it used. i don't think it's them. it sounds like resonant rattling more than anything, and certain notes bring it out more. i really think it's the springs in the reverb tank, or something seated wrong.
i'd like to take out the reverb tank and see if it's that, but i don't know how to get at it. it's sealed from below, screwed in or something. any tips?

edit: got the tank out. see if it's that. i'll keep you updated.

it appears to be the cubical metal thing that's next to the tubes. i'm not sure exactly what it's called, but it's metal, boxy, and has a big old copper strip going through the middle of it. when i touch it, i hear the buzz sound.


   
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(@ricochet)
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That sounds like a transformer. Copper strips are put around them to shield electrical interference. If it's come loose, it could buzz.

"A cheerful heart is good medicine."


   
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(@anonymous)
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Topic starter  

i took it apart and tightened everything, but now it looks like it really is one of the tubes, or possibly the wire that clamps down over the tube to keep it in place. i don't think the problem is old tubes. i think it's that something's rattling, because when i touch it, it stops making the noise.


   
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(@ricochet)
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Joined: 21 years ago
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Finding and fixing vibrational buzzes can be a real headache.

"A cheerful heart is good medicine."


   
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(@ricochet)
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Joined: 21 years ago
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Oh, another thing: Tubes can develop loose parts inside that vibrate. And as they move in relation to one another, they act like a microphone and the sound is amplified. If you identify a tube that stops the buzz when you touch it, that may be the problem. Try tapping it with something like the eraser end of a pencil and see if it makes a loud noise. (Any tube will make some noise if you tap it while the amp's on.) You may need to replace that tube. Tubes are pretty fragile. this is a reason you have to be careful not to bump or drop a tube amp.

"A cheerful heart is good medicine."


   
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(@anonymous)
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it's the first power tube position. i switched the tube with the tube in the 4th position, and the 1st tube position still rattles, or the metal thing holding it in place, or its seat or something connected to it.
i give up. i've spent hours on it, and no improvement. my options now are to buy a tube damper off ebay, take it in to the shop, or go ahead and build a separate head compartment. the last option would be the most work and the most fun, and i'm seriously considering it, but it could also end up being a huge mess.


   
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(@anonymous)
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it's not annoying at lower volumes, and i can always play through my crate, so i'm just gonna let it be for today.


   
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