must you play music to break in tubes

I have some GE 12ax7 longplate tubes that make some loud crackling noises.  The Seller claimed that this is common with nos tubes and that it will go away after they are broken in, but it is too alarming to hear and sounds risky to the speakers.  Might leaving the amp powered up for a while, but with no signal passing, break them in adequately?  Kind of hate wasting the power tubes lifetimes, but I don't have any old tubes to use in that amp.


If your amps are on just play music and on the subject of crackling it can sometimes subside but not always. The crackling will not hurt your speakers in any way.

I use all GE 12 type tubes in my amps and that loud cracking sound is a tube failure. The seller is giving you a line of BS!

New tubes occasionally crackle a little for a couple hours… but at very very low volumes. I have never heard any tubes make sounds loud enough to think of calling or writing about it.

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@yogiboy +1 !!

Bad Preamp Tube Symptoms

There are a few things that are more common when preamp tubes begins to fail. You might experience things like:

  • Crackling
  • Popping sounds
  • Volume loss
  • Squealing
  • Hum or feedback
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I attribute blowing out a tweeter to a bad tube.  The tube was making more of a popping sound than a crackling sound, but none the less.

I have had a number of NOS tubes of different brands, a fair amount were GE 12ax7s and 5751s, but never had a new tube make crackling noises.

As the posters above recommend, send them back.  

Tubes need a break in period? 

Crackling is normal??!

Heed everyone's advice, return them and get your money back from this no integrity shyster.

only time I've seen a crackling sound being normal was when small bits of particles get trapped in the tubes plates during construction/shipping, a hard tap with the back end (handle end) of a screwdriver can dislodge the particles and return to normal operation. If its not that its a a bad tube from my experience. 

+ return 

You can turn the volume down while waiting for the noise to clear.  If it is what glennewdick described, it doesn't take that long to clear up.  The particles will burn up and the problems stop.  I hear that crackling rustling noise very rarely, and it is this issue of flakes falling on the cathode.  In my case, it is an amplifier tube, so I just have to endure the noise until it stops.  That usually takes a few minutes.  This happens with my very old set of tubes once in a great while (in the past 10 years or so, it has happened maybe four times).

I've owned tube amps since the mid 60s, and I will never stand for even a moment of any crackling sound. Others may tolerate that sort of thing, or think up silly explanations based on nonsense to explain it (flakes falling on the cathode? really?), but tubes should sound fresh and noiseless or they will not be used in any of my hifi or guitar amps. I've had preamp tubes (new or vintage NOS) last far longer than predicted by so called "experts" and have had others basically explode immediately...ya never know, but the damn things are generally trouble free for their life span, and any noise gets 'em tossed.

My tubes are dead quiet except for those rare instances I mentioned above.  Get rid of them just for these minor sins--they have worked well for me for a very long time even though they were old and used tubes (tested strong) when I got the amp.  They are also nearly impossible to replace.  The last time I saw these tubes offered for sale, they were of unknown condition AND they cost $2,000 each.  

those sellers really rely on audiophile deity about break-in process. I'm glad that such deity had been debunked and seller is at least getting confronted with return of "NOS tubes that need break-in to stop crackles"

The crackling and sputtering sounds I've heard that went away with time took about a minute or two to go away.  I've heard similar sounds where the tube pins made poor contact with the socket.  You could try cleaning the pins and re-inserting the tubes.  Any really long "burn in" to cure any problem--with noise or poor sound is dubious.  It should not take so many hours that you are concerned with wasting the life of the other tubes.  

+1 @glennewdick & @larryi

If they are true NOS tubes, crackling is not uncommon. Take each tube out. Give it a decent tap. I give noisy NOS tubes a few hard flicks with my fingernail. Re-install. If the crackling persists after 20 minutes or so, it’s probably a microphonic tube. Return if possible. Yet, some microphonic tubes might be unlistenable in the buffer stage but could be totally quiet in the output stage. Or visa versa. It depends on the circuit design.

Just to confirm what others have written, crackling and noise from tubes is not a "break-in" issue.  Return them immediately.

@steakster, @glennewdick & @larryi-


     Had the conversation with Brent Jessee, years back, about a 40's,Tung-Sol Round Plate.

      He had me GENTLY tap the the base, tube held vertically, on a table.   It worked!

                                Never had the issue again.

                 If it doesn't work, in your case: send them back.

        btw: He also includes a letter with tube purchases, that discusses tube break/burn in.      YES: it's real, but I wouldn't waste the tube hours, by not listening to music.      

                          The differences won't hurt your ears.

                                        Happy listening!



I've tapped the tube of tubes with a pencil eraser before with excellent results. Now I'm not telling you to do this, but I'd do it again if I had a little static or popping before giving up on them.

That said, the seller might be full of it as suggested above, very possible, especially with AI, everyones a genius nowadays.

Good luck!