When to power off a tube amp?

I had a NOS JAN Philips 12AT7 flame out in my Jolida last year...harmed nothing, replaced both 12AT7s under warranty (thank you thetubestore) with nice matched CV4024 Blackburn Mullards, and have been living happily ever after. I don't leave the amp on when I'm out, and turn my entire system off at the end of the day or if I'm gone for more than a few hours. The NOS Mullards do provide an entertaining flash on startup, and I don't think new (current repros from New Sensor) ones do that...at least the 12ax7s I have in a guitar amp.

@almarg on the issue of leaving or not leaving equipment powered up, are you suggesting that there is no sonic advantage to be gained from leaving any equipment on except those containg a DAC?  While I have not empirically tested the assumption, I have a sense from experience that leaving gear continuously turned on or at least on standby (all SS until very recently) yields more satisfying listening than shutting all down and starting cold.  This of course comes at some expense both in electric bills and presumably life of equipment.

Also, relevent to this thread, I recently purchased a little hybrid tube phono pre and have been wondering about the logic of warm up as it applies to both tubes and solid state circuits in the device.  My experience is that longer warm up for solid state devices and cable looms yields more better listening to a point, but advice here says for pure tube devices 10-15 minutes should be wholly adequate.

Any insights appreciated.

kn

... on the issue of leaving or not leaving equipment powered up, are you suggesting that there is no sonic advantage to be gained from leaving any equipment on except those containg a DAC?

Hi KN,

No, nothing in my earlier posts was intended to suggest that. As I said in one of those posts:

... the basic point behind my earlier post is that when a tube component, especially an amp, is left on unattended for significant periods of time, in addition to the very small (but non-zero) possibility of fire (which always seems to get mentioned in this kind of discussion), there is also the presumably much greater (but less often mentioned) possibility that a minor failure of a tube or other part will result in major damage to the equipment, if not discovered promptly.

As the experience I cited illustrates, that can even happen as a result of a problem with a small signal tube, especially if the small signal tube is in a power amp or integrated amp.

It seems clear that a case that is at least somewhat reasonable can be made on all sides of these questions, but FWIW my own practice is that the only equipment I leave on unattended are solid state components having no power switch (which are therefore presumably designed with the expectation that they will be left on all the time), and my solid state CDP.

BTW, regarding my reference to "solid state components having no power switch," one such component I have used was a Mark Levinson ML-1 preamplifier. I had it powered up essentially without interruption for about 25 years, and previously it was probably powered up continuously for another 8 or so years while it was owned by someone else. It finally developed a problem after those 33 years of essentially continuous operation, and I replaced it.

Best regards,
-- Al