what makes a tube amp go "crackle", i ask?

[abodean]

i know it's not a recording question, but when recording at low volumes, it is nearly impossible. . .

it's a very low crackle, but evident. when the amp is cranked, it sounds fine, as the guitar going through it is much louder than the crackle. so, you can no longer hear the crackle.

but at lower volumes as would be desired with recording in my home (so as not to wake the sleeping beauty), the crackle destroys the take. it's only started recently, for no apparent reason. just crackle, crackle, crackle. when the guitar's volume is turned completely to the off position, the amp just crackles.

i've never really experienced this problem with my own amps (just heard other amps that were obviously in junk shape that made crackle noises). any simple answers?

thanks so much for your time,
andy

[leigh]

I was just wondering this the other day, as I have an all-tube compressor that started doing the same thing.

I suppose it could be many things, but was hoping that someone might point a finger at a common cause of "tube amp crackle".

Leigh

[sonicmook56]

yea, I know that crackle. My 68' bassman 50 has the same problem at low volume......weird

[drumsound]

what makes a tube amp go "crackle", i ask?

Sumthin's broke.

[inverseroom]

My local amp tech sez: old bad resistors. At least that's what the problem was with my Gibson Skylark. It's quiet now.

[glimmertwins]

I have the same problem in my BF Pro reverb and my Gretsch 6162 Dual Twin. Mine isn't constant though - just a slight crackle every now and again. It almost sounds like the crack of lighting off in the distance - only in my freakin amp!

[sad iron]

I've had the same thing w/ my Vibroverb and found that once it gets warmed up there's no trouble. It just has to get the juices flowiing

[Zeppelin4Life]

oxygen in the tubes can cause it I hear...if you lok at the tubes and see a blue glow instead of orange that could be o2 also

Dave

[@?,*???&?]

oxygen in the tubes can cause it I hear...if you lok at the tubes and see a blue glow instead of orange that could be o2 also

Dave

Here's a vast level of experience speaking...

[sad iron]

oxygen in the tubes can cause it I hear...if you lok at the tubes and see a blue glow instead of orange that could be o2 also

Dave

Here's a vast level of experience speaking...

The guy's 16 and he's contributing and psyched about rock. Why spit your jaded venom at him?

[aurelialuz]

the blue glow thing isn't correct, that's an old wives tale. tubes can glow blue and be fine.

the crackle is most likely a cold solder joint somewhere. if you open it up and power it on, then poke around the components with a wooden chopstick, you might find one that makes that crackle happen. fire up your iron and rehit the solder points around that component, and any other ones that look dull. last two amps i've seen with this problem took five minutes. STAY THE FUCK AWAY FROM THE POWER CAPS.

this doesn't rule out a bad component, as IR pointed out with his bad resistors.

alex

[Dan Phelps]

Sometimes when an amps begins to do this (it sounds like a storm coming in) a gentle thump with the fist will clear it up for long enough to do the take. I don't know why, but that always made me think it was a tube thing.

Dan

[aurelialuz]

Sometimes when an amps begins to do this (it sounds like a storm coming in) a gentle thump with the fist will clear it up for long enough to do the take. I don't know why, but that always made me think it was a tube thing.

but if you think about it, that means it could be anything physically intermittent in the amp.

alex

[Scodiddly]

Could be old power capacitors letting an occasional leak through, or old noisy resistors. Or the tubes, or... etc.

Hard to be certain without having the thing on the bench.

[Zeppelin4Life]

Oxygen will not ruin the tubes. And I am talking from experience. My EL34s used to burn blue in my amp and it crackled. I put JJ EL34s and they now burn orange, and do not crackle