Crackling Amp

RRClassic

Member
Messages
438
Ok, I have a new amp that after about 3 weeks started crackling and Pfffting. I tried the obvious and replaced all tubes with no luck. We thought it might be the input jack which is a switching jack so we cleaned that....no luck. The only thing left I am guessing would be a cap issue.

Anyone know if there would be a typical culprit in the caps that could be the cause? none of the filter caps are malformed or heating up or at least melting anything. The amp sounds great but the crackling is annoying.

Thanks
 

8len8

Silver Supporting Member
Messages
13,591
I had a similar problem and it ended up being a bad/cold solder joint at one of the tube sockets.
 

eupbin

Gold Supporting Member
Messages
315
I had that problem with a HRDLX and replaed all the tubes. Brought into a tech and found out I had replaced with a bad tube! It happens...
 

Lance

Gold Supporting Member
Messages
10,746
Hmm, I have a Tweaker head that's been doing this lately. I just really hate to send it back, because I'm like still using it, and stuff.
 

Aesg81

Member
Messages
25
Cold solder joints at the tube sockets have been the culprit on two of my amps now. Both were older. 76 Princeton Reverb, and 82 JCM 800. If its more than 20 years old, this is very likely it. This problem is so annoying, I did all the things you did too before I figured it out.

In both instances I installed ceramic tube sockets and was done with it.
 

pfflam

Member
Messages
7,119
If it has RCA inputs for Reverb/Vib footswitches, make sure they are well connected

- don't scoff - a simple tightening of one of those connectors saved my Super Reverb when I was beginning to think a transformer was going since I couldn't find the problem.

Also, tightening and cleaning the tube sockets if its kinda old
 

RRClassic

Member
Messages
438
This is a true PTP amp like a matchless etc. I think it may be a cap on the lugs of the volume pot but I am still searching. It could be a cold solder joint but I would be surprised given the nature of the build....it could happen though.

I poked around with a pencil on all of the solder joints while it was on to see if any movement created the crackling which it did not.

It could still be a tube, I suspect a 12AU7 but I have no more to replace it with.

The volume cap did crackle a bit so that is my next experiment.

No fun when you are talking about a $4,000 amp
 




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