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.
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.
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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. |
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