When to power off a tube amp?

... 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

FWIW, a few years ago I installed a brand new quartet of Chinese-made 6SN7 small signal tubes in my VAC amp, that had been provided and tested by a good supplier. After listening to beautifully reproduced music for about 2 hours, all of a sudden there was an eruption of horrific static-like noise from one speaker. I believe it was loud enough, and that it had sufficient high frequency content, to destroy the tweeters in many speakers if allowed to continue for a prolonged period. In this case I had the amp shut down within about 4 seconds, with no damage. I subsequently found that one of the 6SN7's had abruptly developed a short.

I of course have never used any of those four tubes since.

FWIW. Regards,
-- Al

12-26-13: Bifwynne
Al, can I assume, therefore, if one leaves their amp on unattended for even a short period of time, they could learn upon resuming their listening session that not only does their amp not work, they may be minus one or two speakers as well?? Al, there is obviously no written rule out there that I am aware of, ... but at the risk of too quick a turn-off/turn-on, what's your rule of thumb about leaving a tube amp on unattended?

Hi Bruce,

As you realize, 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.

Regarding your mention of the possible risks of turning on too soon after turning off, I second Larry's comment. I can't base that on personal experience, though, as I've always allowed at least a couple of minutes, and usually more, between those actions. Intuitively it just seems to me to not be good practice to do otherwise.

Best,
-- Al