George Juggles
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Join date: Jan 2012
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#1
SO my amp has been making alot of crackling, and static noises. I figure it is just the tubes, but am not sure. But what I don't understand, is that when I play a B note, no matter where it is, it makes the crackling alot worse. What is causing the problems?

Thanks
George Juggles
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tubetime86
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#2
Microphonic preamp tube is my guess. With the amp on, tap each tube with the rubber end of a pencil and listen. Whichever tube amplifies the 'tap' sound through the speaker is the bad tube... Replace it. Done!
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tubetime86
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#4
^I could be wrong, but I believe the fact that it resonates with the 'B' note so distinctly means it is actually a mechanical noise... And the only mechanical noise that I know of that can be amplified through the speaker is microphonic tube noise.

Again I could be wrong... But I don't think I'm wrong in suggesting he rule that out before bothering with anything else.
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BURN THE WITCH!!!!!
George Juggles
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#5
I tried tapping them with a pencil, but they didn't amplify the sound at all. I could just here me.
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#6
Dan, my post does not reflect your post. I just typed up a response and now see that you did too.

I've had microphonic tubes before. As a matter of fact I made a video of it along with the pencil test.

I've also had a crackling preamp tube and that was due to a tube pin arc'ing with the board.

Can't speak to the B note situation.

What amp do you have TS?
Last edited by 311ZOSOVHJH at Oct 16, 2012,
tubetime86
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#8
Wow that's odd... Apparently I was wrong, and given that I have no clue.

The fact that it gets worse with a B note means that is the frequency it's resonating at... Which in my mind means mechanical issue... But who knows. I'm gonna wait until a tech, such as Cathbard, joins in.
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Unless its electronic drums.

BURN THE WITCH!!!!!
George Juggles
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#10
It's been starting to do make the sound worse with a C# note too. It doesn't make the sound when I play an open string
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Cathbard
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#11
Highly probable that it's a microphonic tube but it could also just as easily be a poorly seated tube or dirty tube socket. That is affected by resonance too.
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#12
Quote by George Juggles
I tried tapping them with a pencil, but they didn't amplify the sound at all. I could just here me.

The question is can you hear the tapping through the speaker.

Does that amp have an extension cab out? Try it with an extension cab.

Does your amp have an effects loop? Try plugging guitar into FX return.

Have you swapped any of the tubes around like I suggested?

You could have bought 1 preamp tube and had it in there by now. You could have a microphonic preamp tube like Dan was saying.
George Juggles
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#13
It has an extension cab out, but don't have an extension cab.
I will try the fx loop.
I will try swapping around tubes.

And no, I could not hear the tapping through the speaker.
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#14
Get some of this



and then hit the tube pins with it and work the tube in and out of the socket like it was having sex and then make sure all the tubes are seated down real good like Cath is saying.

Also - is the crackling more of an electronic crackle or more like a loose screw crackle?
George Juggles
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#15
I don't really know how to describe it.

I swapped around the tubes, but it still makes the sound. I tried plugging my guitar into the fx return, and it still crackled, but it is not quite as noticible as in the regular input.
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George Juggles
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#16
Is the deoxit stuff that you have in a tube or spray bottle?
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#17
spray bottle

it is contact cleaner

I'm starting to think that won't fix anything but in general - it is good to keep your pins and sockets clean

I've heard of 'ghost notes' before but I wouldn't know if that has anything to do with it or not without doing more research.

Separately-

Sometimes in combo's when the tubes are real close to the speaker like that you can get some weird stuff. A microphonic tube would not necessarily show itself on a pencil test. But with the speaker real close like that then it could highten a note I suppose. That was partly why I asked about an extension cab. Can you take your amp to a store and plug it into a cab and see what happens.

I personally would swap some tubes around for now.
Last edited by 311ZOSOVHJH at Oct 18, 2012,
Offworld92
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#18
Quote by 311ZOSOVHJH


and then hit the tube pins with it and work the tube in and out of the socket like it was having sex



That was really funny to me for some reason.

Carry on.
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George Juggles
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#20
What do you mean by a retainer? The little metal things that go down and around the tip of the tube?
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#22
Does it have built in reverb? If so disconnect it and see. (it's worth a shot, but as he stated it did with fx loop it's very unlikely to be from reverb)

TS have opened your amp up yet?

Have you wiggled the speaker cable?

It sounds like a connection issue with a power tube socket due to concern still present with guitar into FX loop. Could also be fried internal/poor solder connection.

Everyone has posted great suggestions. Obviously do the easiest first then move on to the next step.
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#23
If you don't have contact cleaner you can clean the sockets after a fashion without it. Pull out the tube, clean any crap off the pins. Then stick it in and out of the socket about 3 times. Look at the pins on the tube - are they clean? If so, stick it in and make sure it's seated properly. If not, repeat.

But buy some contact cleaner, it isn't expensive. It will clean everything far, far better. You do what I described above but you spray the contact cleaner onto the pins between cleaning the pins and working it in and out of the socket.
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George Juggles
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Join date: Jan 2012
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#24
Quote by R45VT
Does it have built in reverb? If so disconnect it and see. (it's worth a shot, but as he stated it did with fx loop it's very unlikely to be from reverb)

TS have opened your amp up yet?

Have you wiggled the speaker cable?

It sounds like a connection issue with a power tube socket due to concern still present with guitar into FX loop. Could also be fried internal/poor solder connection.

Everyone has posted great suggestions. Obviously do the easiest first then move on to the next step.


It does have built in reverb, so I will try that.
No, I have not opened up my amp yet.
I will try to wiggle the speaker cable.

Quote by Cathbard
If you don't have contact cleaner you can clean the sockets after a fashion without it. Pull out the tube, clean any crap off the pins. Then stick it in and out of the socket about 3 times. Look at the pins on the tube - are they clean? If so, stick it in and make sure it's seated properly. If not, repeat.

But buy some contact cleaner, it isn't expensive. It will clean everything far, far better. You do what I described above but you spray the contact cleaner onto the pins between cleaning the pins and working it in and out of the socket.


Thanks, I won't be able to get contact cleaner right away, but I will clean the tube pins.
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George Juggles
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#25
I cleaned off the tubes, power and pre amp, and it didn't do anything. I'm probably just going to replace all the preamp tubes, since it is them that seems to be the problem
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