Buzzing all-tube amp... How to make it stop?

varador · #1 01-20-2008, 12:52 PM

I damaged my Peavey Valveking 112 this morning when I plugged my Boss RC-20XL into the effects loop while the amp was turned fully on (not on standby). I plugged the last cable of the loop into the "Return" plug of the amp's effects loop, and as I did so, there was a LOUD gunshot-like crack/pop. The amp was set at a bedroom volume, but this crack/pop sound was much louder than the volume the amp was set to. I'm sure this was not good for the amp, and I already knew that I should always insert/remove patch cords (from inputs / effects loops) when the amp turned off or at least on standby, but I guess I was in an impatient mood (been a bit grumpy about my RG350's relatively thin sound lately). Shortly thereafter, there was a constant passive buzzing noise from the amp. Plugging in / removing the guitar and the effects loop doesn't help, the amp is buzzing even if nothing is plugged in.

Later, I was dumb enough to repeat the mistake - I flicked the amp on standby but didn't wait long enough for the tubes to fully go out, and I yanked the cable from the "Return" plug in the effects loop, yielding another loud gunshot/crack/pop sound. Worried that I may have further damaged the amp, I removed every cable from every jack in the amp, flicked the standby switch back on, and, yep, the buzzing was there, stronger than before.

Now, question is - what kind of damage have I wreaked upon my amp to cause the buzzing? I'd expect it's a circuitry / tube issue, maybe a ground wire gone loose? Advice please. I know it's an amp issue, not a guitar or stomp box problem...

shotgunlew · #2 01-20-2008, 01:51 PM

I have this issue with my jcm 800 combo so id like to also hear about this. My buddy said it was bad tubes or they need to be re biased. Id like to hear a more knowledgeable response from someone one here.

Whey · #3 01-20-2008, 05:45 PM

Answer: Class AB amp, over used/"bad" tubes magnify the problem. Biasing is not a problem seems its Peavey (self biasing). Could be a lot of things depending on the quality of parts but most AB amps buzz quite a lot, chances its messed up is quite slim.

Solution: a real Class A amp

dahjem · #4 01-20-2008, 11:48 PM

Mike Soldano suggestion...turn your gain/preamp volume way up, and slowly turn your master/poweramp volume down. If the noise stops when master is turned down, your in luck, preamp(s). If the noise persists, output tubes or worse. Hope that helps. BTW...a soldano will cure ALL thin sounding problems...I promise!!

varador · #5 01-21-2008, 08:34 AM

The buzzing sound isn't too bad, I mean I'm not exactly a studio artist or anything and I've gotten used to it, doesn't seem to be too bad. At least it keeps me aware when the amp is on

If it's a tubes / speaker issue then that's good news, as I'm intending to replace both of those in the Valveking eventually.

Whey: the Valveking can switch to Class A only using the Class A/B vs. Class A selection knob, I'll give Class A a try and see if it still buzzes...

dahjem · #6 01-21-2008, 11:36 AM

Just a long shot...but if the noise isn't too bad, are you sure there's no lighting/dimmers interfering or a ground loop type of issue?

bammbamm · #7 01-21-2008, 01:25 PM

Check cabling, grounding, both- on your guitar and amp, as was said, light fixtures, CRT monitors all lend a hand in making noise in a tube amp.

Good luck.

toma · #8 01-22-2008, 07:05 PM

class A?
class A/B?
wtf?

whats my hotrod deluxe?

x

millzy · #9 01-24-2008, 03:16 PM

yep this happened to me also
ive come to the conclusion that the valveking is possibly the worst sounding amp thats valve wired avadiable. I even bought new speakers (v30's) and its still sound like somebody's kicked it alot..

varador · #10 01-27-2008, 01:33 PM

valveking only sounds as good as what its amplifying

i like it. is a v30 swap honestly worthless?

microdmitry · #11 01-27-2008, 09:17 PM

Quote:

Originally Posted by dahjem

Mike Soldano suggestion...turn your gain/preamp volume way up, and slowly turn your master/poweramp volume down. If the noise stops when master is turned down, your in luck, preamp(s). If the noise persists, output tubes or worse.

+1 on this one. This is how you check any master volume amp to identify the problem segment. Buzz is unlikely to originate in the power amp, though. Power amp can hum quite a bit when one of the power tubes (or a pair, if you have four) is bad or heavily mismatched.

Have a tech take a look at it. It should take about five minutes to identify the issue.

Repner · #12 01-28-2008, 04:31 PM

I just received my G-Major in the mail today, and now whenever its plugged into the effects loop of my Marshall DSL 50, I have the same problem. I turned both gain and master down and it was still there. No hissing when I take the G-Major out though. I think I'll take it to a tech and see if they can help me with it

chris101 · #13 01-28-2008, 06:27 PM

Quote:

Originally Posted by varador

I damaged my Peavey Valveking 112 this morning when I plugged my Boss RC-20XL into the effects loop while the amp was turned fully on (not on standby). I plugged the last cable of the loop into the "Return" plug of the amp's effects loop, and as I did so, there was a LOUD gunshot-like crack/pop. The amp was set at a bedroom volume, but this crack/pop sound was much louder than the volume the amp was set to. I'm sure this was not good for the amp, and I already knew that I should always insert/remove patch cords (from inputs / effects loops) when the amp turned off or at least on standby, but I guess I was in an impatient mood (been a bit grumpy about my RG350's relatively thin sound lately). Shortly thereafter, there was a constant passive buzzing noise from the amp. Plugging in / removing the guitar and the effects loop doesn't help, the amp is buzzing even if nothing is plugged in.

Later, I was dumb enough to repeat the mistake - I flicked the amp on standby but didn't wait long enough for the tubes to fully go out, and I yanked the cable from the "Return" plug in the effects loop, yielding another loud gunshot/crack/pop sound. Worried that I may have further damaged the amp, I removed every cable from every jack in the amp, flicked the standby switch back on, and, yep, the buzzing was there, stronger than before.

Now, question is - what kind of damage have I wreaked upon my amp to cause the buzzing? I'd expect it's a circuitry / tube issue, maybe a ground wire gone loose? Advice please. I know it's an amp issue, not a guitar or stomp box problem...

You might have blown a ceramic coupling cap, open her up, (mind you dont kill yourself), look for any burnt up (blackened) or dry joint ceramic caps, especailly near the power amp tubes.