A tube amp ought not to do this.

[Darg1911]

Re: A tube amp ought not to do this.

Funny, in my experience the poping noises described have always been power tube issues along with volume fluctuations.

Funny as in I'm full of s**t or funny as in interesting? J/K.

The OP mentioned both "popping" and "rustling". Could be either pre or power tube, if it's a tube. Personally, I'd start with the preamp tubes.

 

[Gtrjunior]

A tube amp ought not to do this.

Lol!! I wasn’t busting your balls!! I meant interesting.
Yes, Preamp would definitely be cheaper especially is the op has a few on hand.
I have found in my amps that the preamp tubes can and often do last years...and I mean decades. I have some NOS in my JCM 800 from the 60’s and they are still going strong. I run new production tubes in my Quickrod. I just feel they sound better in that amp then the NOS I’ve rolled through it.
https://youtu.be/IWINtUCshxY

 

[FuseG4]

Re: A tube amp ought not to do this.

Had this problem the other week, had popping noises intermittently, sometimes volume drops, and a weak mushy bass, after two weeks of that kinda thing it just quit. It was probably a year old and was a groove tubes sovtek.

And yeah failure rates on brand new tubes can be bad and sometimes even tubes that tested good on some guys tester may show problems after several hours of real world use.

 

[Little Pigbacon]

Re: A tube amp ought not to do this.

You know, I have a backup set of JJ EL34’s, Apex matched, and I have a bunch of 12AX7’s, but I don’t think I have any more Chinese preamp tubes for the cathode follower positions. There is always something to buy.

 

[Gtrjunior]

A tube amp ought not to do this.

You know, I have a backup set of JJ EL34’s, Apex matched, and I have a bunch of 12AX7’s, but I don’t think I have any more Chinese preamp tubes for the cathode follower positions. There is always something to buy.

I had good luck with the TAD brand Chinese tube for the cathode follower.

Here’s what I’d do:
Turn the amp on and let it warm up (make sure the speaker cab is connected)

Remove the back panel and do the chopstick test. Remove and replace any preamp tube that is excessively noisy or make a ping type noise (except V3, the cathode follower...just leave that one alone for now). But make sure you change the tubes one at a time or you’ll never narrow down the culprit with 100% certainty. Also keep in mind the V1/2 are the gain stages. It’s not uncommon to hear more noise from those slots.

Lastly do the same with the power tubes.

Question-
Are you 100% certain that your amp is properly biased?
Bias can and often does drift.
You may just need to bias up and take it from there.

If you are certain that you are biased properly and still are getting the symptoms you described I suspect you need to change and bias in a new set.
Like I said in a earlier post, ime the symptoms you describe sound like power tubes.
I own 3 tube amps and NEVER had a preamp tube go on me yet.

 

[dystrust]

Re: A tube amp ought not to do this.

You know, I have a backup set of JJ EL34’s, Apex matched, and I have a bunch of 12AX7’s, but I don’t think I have any more Chinese preamp tubes for the cathode follower positions. There is always something to buy.

Do you have any JJ 12AX7s?

You really only need to avoid the following New Sensor 12AX7s: EHX, Genelex, Mullard, Svetlana, Tung Sol, and Sovtek LPS. The older Sovtek 12AX7WA, WB, & WC are fine.

I had good luck with the TAD brand Chinese tube for the cathode follower.

I also use Shuguang 12AX7s for cathode followers, but that's mostly because amp manufacturers keep giving them to me, and because I don't like how they sound as a gain stage or PI.

Like I said in a earlier post, ime the symptoms you describe sound like power tubes.
I own 3 tube amps and NEVER had a preamp tube go on me yet.

I've had a few preamp tubes fail. They can cause crackling and microphonics as well as decreased gain and changed frequency response. I once had a weak V1 tube lose most of its bass response; made the amp painfully bright until I figured out the cause.

 

[ehdwuld]

Re: A tube amp ought not to do this.

*sighs*
Does it have an effects loop?
Speaker cable jack?
Input jack?

Check those the popping sounds like a loose connection