Crackling after the amp has been switched on

[Leevi]

What could be the reason for crackling after the amps has been switched on?
It disappears after some ten seconds when the amp has warmed up.
/Leevi

[aro]

I had (and I guess I still have) intermittent crackling when switching on the amp, for more than 10 seconds. Sometimes it would come and go as I was slamming my fist on top of it. Eventually it would go away. I opened it up, checked all the connections, wiggled all the wires etc etc.

Eventually I realized it happens only after the amp was out in the cold for a longer time (like in the trunk). Don't know if it helps...

[Ritchie200]

Do a quick clean on your sockets/tube pins - usually preamp, they are usually the main culprit.

Jim

[Leevi]

Eventually I realized it happens only after the amp was out in the cold for a longer time

Yes, I noticed the same.

Do a quick clean on your sockets/tube pins - usually preamp, they are usually the main culprit.

I try to localize it by disconnecting part of circuit/removing tubes.

/Leevi

[plexi50]

Do a quick clean on your sockets/tube pins - usually preamp, they are usually the main culprit.

Jim

I second that: I have had to toss some beautiful old excellent testing NOS preamp tubes because of hiss and crackling
That hurts worse than the $100.00 cash i left lying on the Bank teller window 3 months ago

[samato]

How about if the crackling also happens when turning the bass control pot?  Could that also be tube related?  I ask because I have what the original post describes and this other symptom and it doesn't really sound like what I know as a dirty or worn out pot.  I could be wrong though.

[jeff]

 Usally if a pot makes noise as you turn it there is DC on it. As you turn it back and forth, back and forth does it sound scratchy? Check for DC, may be a leaky cap.
Crackling as it's running may be a symptom of bad resistors. Is it an old amp?

[Tone Junkie]

My first Plexi I built I had cracking that drove me crazy checked all the wires resoldered the points on top of the board finally got pissed and yanked the board out seems I hadnt soldered one wire perfect underneath the board on my B+.
I put it back together all is well, unfortunatly as the wise man said the problem is always in front of the amp. In my case anyway  . Bill

[samato]

Usally if a pot makes noise as you turn it there is DC on it. As you turn it back and forth, back and forth does it sound scratchy? Check for DC, may be a leaky cap.
Crackling as it's running may be a symptom of bad resistors. Is it an old amp?

Not scratchy as I turn it, just crackles (or maybe it's a pop) sometimes.  I'll check for DC though, haven't done that yet.

It's a new amp, though some parts are recycled but I don't think that applies to the resistors.  I could be mistaken.  I probably should check as much as I can just to see what's going on.  Not sure how to go about all that.  I kind of thought if the voltages are okay on all the tubes that means all the parts are good.  Is that wrong?  Anyway, it's been a while since I checked my voltages so I'll go through it again.

[jeff]

Not scratchy as I turn it, just crackles (or maybe it's a pop) sometimes.  I'll check for DC though, haven't done that yet.

OK probally not DC then.

[RicharD]

What kind of amp is it?  I know a Super Reverb who crackles for a solid 5 minutes and then she's fine.  I believe it to be a conductive board that once warmed up stops conducting.  It could be a plate resistor, it could be a lot of thangs.  10 seconds isn't much time to troubleshoot for a bad part.

[sluckey]

You may be able to locate it with a can of freeze spray.

[Leevi]

What kind of amp is it?

It's an SE bass amp to which I have opened another thread here:

http://www.el34world.com/Forum/index.php?topic=11127.0

The problem is now solved: The root cause was the power tube (brand new 6L6 from JJ).

/Leevi