problem with amp

D

donkeystyle

New member
i'm having a problem with my amp. i think it's most likely a pre amp tube, but i want your opinions. i was going to test it tonight, but i forgot it at the other guitar player in my bands house, so i wont be able to test it until next tuesday.

ok. so this is what it's doing. it's popping. when i turn the amp on, the for the first couple minutes, it doesn't do it, but once the tubes warm up, it starts and it'd not random. I mean I could probably keep time with it. i've eliminated guitar cables, speaker cables, and effects pedals as the problem. i can turn the standby switch on and leave it like that for a couple minutes and when i turn it back off, it doesn't do it for about 30 seconds, maybe a minute.

some history on the amp: a few months ago, i had a problem with it.....it's a rivera knucklehead and there's a known problem where one of the resistors on the v3 part of the board goes out. I replaced the resistor with the one rivera suggested, it fixed the problem i was having, but then the channel was really quiet. i didn't have the time or experience to trace the problem, so i took it to a tech. i had him clean my solder job up and check it out. he said he found 2 other resistors that were bad and replaced them. I had just bought new pre amp tubes from another store and he told me that one of them was messed up.......he didn't explain what exactly was wrong with it. he didn't tell me I shouldn't use it, so i just used it. I'm thinking maybe that's the tube that's causing the problem.

what do you guys think? tube problem, or problem with some of the work that has been done?

i guess this is kind of a waste of your time,since i'm going to replace the tubes on tuesday and i'll find out for sure then, but i can't stop thinking about it.
 
i just realised something. it's got to be a tube. the problem with the resistor only effected one channel. i can hear the popping on both channels of the amp.

i was freaking out for no reason. well unless it has nothing to do with the pre amp tubes or the the work i had done on it.
 
Actually, It sounds like a power tube problem. Popping noises are usually "arcing" in the power tubes. Pre amp tubes usually are more of a hum or buzzing issue. Especially since you mentioned that it stops for a while when you put it in stand by. Try looking at the power tubes in a dark room while it's popping.You may see flickering in the tube.

Of course this is just speculation. It could be a number of things. One things for sure...whatever it is , it's not good for the amp. Don't let it run too much with this problem or something more serious could develope.
 
Popping in tube amps could be corrosion in any tube socket. I would take the tubes out and clean the sockets with electrical contact cleaner (the type with out lubrication) If you see anything that looks out of the ordinary use a toothbrush. If it is still popping afterwards don't use the amp until you get it looked at by a pro.
 
goldtopchas said:
Actually, It sounds like a power tube problem. Popping noises are usually "arcing" in the power tubes. Pre amp tubes usually are more of a hum or buzzing issue. Especially since you mentioned that it stops for a while when you put it in stand by. Try looking at the power tubes in a dark room while it's popping.You may see flickering in the tube.

Of course this is just speculation. It could be a number of things. One things for sure...whatever it is , it's not good for the amp. Don't let it run too much with this problem or something more serious could develope.
Click to expand...

Second that. Arcing in power tubes can cause that popping sound, and continuing to run the amp when it is doing that can be very bad for the high voltage DC power supply, which is a major component of the amplifier. This can cause the power tranformer to catastrophically fail (read: smoke), which makes for a very pricey repair job.

Look at the power tubes when the popping is happening. If it looks like lightning in a bottle, turn off the amp immediately and have the amp serviced. It may not be as simple as just replacing the power tubes, and you'll want to have the bias set anyway if you do replace them, so unless you've got some experience at this stuff and a pretty well equipped electrical workbench, this is a job for a pro.
 
i posted this same question on the rivera board. 2 guys have had the same problem. it turned out that it was a preamp tube. the strange thing is that they both had the problem with the groove tube mullards. i'm pretty sure that's what i used last time i changed tubes.

i forgot to tell you guys that you cant hear it unless you turn the preamp gain up a lot. i turned the pre amp gain almost all the way down and the master all the way up and you couldn't hear it. that's why i didn't think it was power tube related.

on a side note, at work i got about a 1 inch long by half inch deep cut on my hand today. my left hand. i wont be playing guitar for a while.
 
MadAudio said:
Ouch! Bummer. I hope it heals well.
Click to expand...
i hope it does also. the pain killer is wearing off and i'm starting to get some feeling back in it, i'm not sure i want that yet.

thanks for caring
 
I'm recovering from an injury myself. I tried playing my guitar the other night and I could barely bend any notes, and holding chords for too long was hurting. It was really frustrating.
 
You must log in or register to reply here.
Back
Top