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-   -   My amp's shrieking (http://www.ultimate-guitar.com/forum/showthread.php?t=1574508)

CheesyMozarella 11-24-2012 11:24 AM

My amp's shrieking
 
I've had this problem before, and then I got it fixed. I don't really remember what he did, but I think he changed one or more tubes. Anyway, now, 8 months later the noise is back.

The amp is a Peavey ValveKing 212. I'm guessing it has something to do with the tubes, but I don't even remotely know my way around amps, so I hoped that this problem would sound familiar to you guys.



It gets pretty loud, so you might want to check your volume.

Blktiger0 11-24-2012 01:08 PM

I'll be honest, I didn't hear any shrieking. Some weird percussive noise, but not what I was expecting.

I can't be sure because of what I heard versus what you're describing, but I would suspect a Microphonic Tube. I think 311 has a video on how to test for this, but basically, you turn your amp on and tap the preamp (smaller) tubes with the eraser of a pencil. If one of them makes noise through the speaker, it's microphonic. It's a more common issue with combo amps. What tubes are you using in that?

CheesyMozarella 11-24-2012 01:12 PM

Hey, thanks for your reply.

I guess shrieking isn't really the right word, but it buzzes and clicks for a while until it starts rumbling (like at 0:34). And it doesn't stop until you turn it off (I had to turn it off here, or my neighbours probably would have killed me).

I'll try to find out what kind of tubes I have.

Robbgnarly 11-24-2012 01:35 PM

the VK uses 12ax7 (ecc83) pre-amp tubes and 6l6 power tubes.

Blktiger0 11-24-2012 01:45 PM

I meant what brand and model. If his tech is putting in JJ ECC803's, that could be the issue. Those are known for going microphonic in combos because of the excess vibration they're subjected to.

Cathbard 11-24-2012 02:19 PM

Pull the tubes out and plug them back in again. If you have some contact cleaner spray it on the pins. That popping sounds like a dodgey connection.

CheesyMozarella 11-24-2012 03:50 PM

The smaller ones were ECC83 and the bigger ones were Ruby 6L6GCMSTR

Unfortunately, I don't have any contact cleaner. I'll try to pull 'em out and put them back again.

By the way, does their positioning matter?

Cathbard 11-24-2012 10:57 PM

By positioning you mean in place properly? If they aren't seated properly you can get a little gap which causes der spitzen sparkenz. Filth will do the same thing. Pulling them out and plugging them back in again will clean them after a fashion as well as ensuring that they are plugged in properly.

CheesyMozarella 11-25-2012 12:15 AM

I meant like, the one to the far right must be in the far right socket etc. Either way, I put them in the exact same spots as they were in before. To no avail though, still alot of noise.

Cathbard 11-25-2012 12:31 AM

Buy some contact cleaner (not WD40, proper contact cleaner like Deoxit) and give everything a good clean. To do the tube sockets spray some on the pins and work it in and out of the sockets a few times. ie the tube is your applicator.
Do the same with all the other sockets - input, speaker, fx loop, etc using a plug as your applicator.

It could be lots of things really but try a good cleaning first. It could be a broken solder joint, dodgey pot, faulty tube socket, faulty cable., dicky switch. Try the easy things first.

R45VT 11-25-2012 12:39 AM

Check the tubes first.

There was another guy on here with the same amp that just had bad pot solder joints. You can get a bunch of different noises from that.

Cathbard 11-25-2012 12:42 AM

Yeah, I was thinking that. What a pita. Have I mentioned how much I hate PCB mounted pots? :haha:

R45VT 11-25-2012 01:01 AM

Quote:
Originally Posted by Cathbard
Yeah, I was thinking that. What a pita. Have I mentioned how much I hate PCB mounted pots? :haha:


Never. :haha:

Blktiger0 11-25-2012 05:50 AM

Quote:
Originally Posted by Cathbard
Yeah, I was thinking that. What a pita. Have I mentioned how much I hate PCB mounted pots? :haha:


In fact, I thought you preferred them :haha:

Btw, glad you could help him. I was confused by his description being a shrieking sound, when all I heard was popping, but I know some cameras don't pick up the sound correctly and then Youtube compresses the video.


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