My amp is squealing and popping

NBW

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It’s occasional and annoying. The amp in question is a Gibson RV Super.
 

LSchefman

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Squealing and popping is usually a microphonic preamp tube. Not always, but often.

If you tap on the tubes with a chopstick or pencil, with everything unplugged from the amp, and you hear tapping loud and clear from the speaker when you tap one of the tubes, it's that tube. All you have to do is replace it.

Note, however, that sometimes you hear some tapping when you tap on the v1 preamp tube (the one closest to the input). That's normal, unless it's quite loud.
 

NBW

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Squealing and popping is usually a microphonic preamp tube. Not always, but often.

If you tap on the tubes with a chopstick or pencil, with everything unplugged from the amp, and you hear tapping loud and clear from the speaker when you tap one of the tubes, it's that tube. All you have to do is replace it.

Note, however, that sometimes you hear some tapping when you tap on the v1 preamp tube (the one closest to the input). That's normal, unless it's quite loud.
This is exactly the kind of advice I need. I think I put in a matched set of power tubes not that long ago and I was hoping that wouldn’t be the issue.
 

LSchefman

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This is exactly the kind of advice I need. I think I put in a matched set of power tubes not that long ago and I was hoping that wouldn’t be the issue.

I hope to heck I'm right! But you'll know once you do the tube tapping thing.
 

RickP

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SinSir

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This is exactly the kind of advice I need. I think I put in a matched set of power tubes not that long ago and I was hoping that wouldn’t be the issue.

I just had a similar issue from a set of power tubes I picked up. Rattle and popping, no squealing. Swapped back to old tubes and problem went away. Haven't diagnosed any further yet.
 

RickP

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I just had a similar issue from a set of power tubes I picked up. Rattle and popping, no squealing. Swapped back to old tubes and problem went away. Haven't diagnosed any further yet.
It might be in the power section, you never know, but it’s the squealing in particular the hints at a preamp tube. It’ll make that noise, often, with a guitar even plugged in. I’m curious to see!
 

SinSir

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It might be in the power section, you never know, but it’s the squealing in particular the hints at a preamp tube. It’ll make that noise, often, with a guitar even plugged in. I’m curious to see!

I agree. Initially it freaked me out a little bit, more so the girlfriend with the pop. Part of my troubleshooting 101, I trace back to the last thing done and go from there. I do think I have a preamp tube issue as well. In my case I'm wondering if the new tubes amplified the issue.

Thanks for the useful link!
 

Going Modal

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Les is correct about checking for microphonic preamp tubes with a wood pencil, chopstick, or wooden spoon, etc. However I've also recently had some power tubes going bad, which resulted in some crazy squealing & intermittent cutting-out. I peeked around back to see one of the two power tubes glowing purple-red in a way that didn't look good. Turned it off right away, then changed the power tubes... all better now.
 

DISTORT6

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Les is correct about checking for microphonic preamp tubes with a wood pencil, chopstick, or wooden spoon, etc. However I've also recently had some power tubes going bad, which resulted in some crazy squealing & intermittent cutting-out. I peeked around back to see one of the two power tubes glowing purple-red in a way that didn't look good. Turned it off right away, then changed the power tubes... all better now.
I can vouch for getting whacked with a wooden spoon. They were my mothers weapon of choice.
I’m a survivor.:D
 

NBW

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After tapping on stuff I think it’s the phase splitter. This amp has a ton of 12ax7s - 5 of them and two 12at7s. I just ordered a bunch of JJs as they are inexpensive and apparently came stock. It is an amazing and somewhat idiosyncratic amp.
 

NBW

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Well I was wrong. I replaced all the pre amp, effects loop and reverb tubes. It was still popping. Then I looked into the power section (the front panel was off) and I could see one of the el84s glow super brigh and the it would pop as it discharged.

that was one of a matched set of JJ el84s I installed not too long ago. I put the Mullards that came in the amp back, which cured the pop, but now it’s noisy (probably why I retubed it.
 

LSchefman

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Well I was wrong. I replaced all the pre amp, effects loop and reverb tubes. It was still popping. Then I looked into the power section (the front panel was off) and I could see one of the el84s glow super brigh and the it would pop as it discharged.

that was one of a matched set of JJ el84s I installed not too long ago. I put the Mullards that came in the amp back, which cured the pop, but now it’s noisy (probably why I retubed it.

New Mullards are just re-branded Sovteks. With an EL84 amp tube matching is less important. I'd just put the working JJs back in, and buy another JJ. For new tubes (as opposed to NOS), they're usually pretty good.
 

NBW

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I think the Mullards have lower output and somehow worse shielding. I just ordered another JJ el-84 so I’ll put those back shortly.
 

LSchefman

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I'm an NOS person, so, yes, kinda spoiled on very good, classic tubes. However, IMHO of the current tube offerings, JJ are perhaps the least problematic.
 
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