When to power off a tube amp?

FWIW for those unaware, the Lyr is a dedicated hybrid headphone amp, the tubes in it do not provide power per se. Most all of the 'dire' consequences of leaving tube power units on unattended just don't exist for this kind of unit, any more than they would for a full sized hybrid power amp, integrated or otherwise.

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

Well apparently turning on the amp is what decreases the life of the tubes? Does it decrease the life more than just leaving it on for that hour of absence? I really want to know as I am buying some Amperex pinched waists 6922 with D-getters which are considered the rarest tube in the 6dj8 family and they are not cheap... So I need to prolong their life as long as possible.

Also, if I don't let the tubes warm up before use, what happens? Decrease in tube life or does it just sound bad?

I own a Lyr and love it although it's had about 8 hours of use since it was new. I let it warm up for about 3-5 minutes. You can't hurt the tubes by listening immediately. If I'm getting up to prepare dinner and plan to continue listening later it stays on. If I'm not going to listen for another hour and a half I shut it off.

I personally would not run this headphone amp with extremely expensive and rare tubes. I'd do that with say a high end all tube unit, but not the Lyr. No reason other than why spend half of what the unit costs on tubes? I'm sure there's plenty of great sounding tubes that aren't as rare or expensive. I still run stock only because I barely use the Lyr to justify owning it.

Highroller, whenever this topic comes up there is disagreement. I haven't seen one of these discussions come to an agreement anyway.

Personally, I think the preponderance of the evidence indicates that you should turn your tube preamp off if you are not going to be listening to it within the next two hours.

You want to avoid turning it on and off several times a day also, but to let the tubes burn for hours while not listening is just using them up with no benefit. Turning them on for 10 or 15 minutes of listening doesn't make sense either. If you want to listen for a few minutes use your computer.

If you are using inexpensive current production tubes, leave them on all day and have a spare set handy. Put the new ones in every once in a while and when the new ones sound better than the old ones, leave them in and order another pair.

That's my opinion. I would call the people at Schiit and ask them what they recommend.