12-hour tube warm up?

I've usually read that tubes have a warm up time of about 30 minutes, but I'm suspicious that my system doesn't reach it's peak until maybe 8, 10, or 12 hours. This is with preamp tubes. Has anyone else noticed that sort of thing?

 

I am envious your stereo is able to be enjoyed for that long in a setting!

 

With the price of tubes, I wouldn't want to throw those 12 hours down the drain.

 

What do you base your suspicions on?

 

My Atma-Sphere OTLs take about a half hour to warm up, so I play a CD and usually handle lose ends around the house before settling in with vinyl and a enjoyably good listen. At the roughly two hour mark, they really come into their own and the increased bloom is obvious in the midrange. But I don't find this suspiciously a tube (amp) thing, as it happened with my solid state gear as well, but the changes were more gradual and not as obvious, all-be-it the end result was rather dramatic. Then again, these tube power amps and the tubed pre-amp smoke my old SS stuff musically in every way. So one could conclude that a more transparent rig, also reveals its warm up characteristics move obviously too.

 

Most tube gear I have had in my system sounded just fine after about 15 minutes of warmup. On the other hand, solid state gear seems to take MUCH longer, which is why some people leave the gear on all the time (my music server is on all the time per the manufacturer's recommendation).

 

No.

1/2 hr or less...

 

That does not make sense to me. That's a long time.

 

Overkill

 

Thanks for the responses guys. This is based on listening throughout the day and noticing the sound is at its best at the end of the day. My system is completely off the grid so it is not an EMI issue.

 

With regard to solid state you make a good point but it doesn't apply to a music server. There's no harm in leaving it on all the time but no sonic benefit either. That is unless your music server is actually a "player", i.e. its circuitry includes a transistorized DAC the analog output of which is sent to your receiver/amp. If your server simply sends data around your house -- like mine does -- the only reason to leave it on is convenience.

 

In China when I first got into tubes and had my first amp with cheap Chinese tubes I left it on 24/7 sitting on a hard ceramic tile floor. The only time it went off is if the power in my apartment went off. To be honest those cheap Chinese tubes lasted a long time with continual power, I'd swear it was on for 3 or 4 months at a time with no shut down. Then after 6 months or so the sound would become distorted and I knew it was time to go buy a new quad of 6L6's for about $18-$20.

 

The designers of Naim solid state electronics insist that it takes at least a day for their gear to be fully "warmed up;" by that they are primarily talking about the various power supply capacitors being fully formed and stable. The same probably applies to tube gear as well. I tend to think that tube gear warms up faster than solid state, but, it may well be the case that the improvement in sound over a short warm up is much more dramatic with tube gear making me think that the full warm up is faster.

As to your noticeable improvement in sound at the end of the day, perhaps it can be explained, at least in part, by a difference in mental state at that time moreso than a change in the system itself.

 

Suspicions confirmed. So the question becomes, why not leave my gear on all the time? Right now I leave it on all day but not all night.

I've read of power tubes starting a fire, but is that a real risk with 6922s and 12AX7s?

How quickly will I go through tubes leaving them on 24/7?

 

I appreciate it when manufacturers weigh in on if they feel gear should be left on or not. I have some gear that I feel might sound better when its been on for a while, but is inconvenient to do so (my battery-only phono stage, for instance), and its good to know what the designer has to say.

 

I read that people are hearing audible benefits after leaving tube gear on for hours and hours, and I don't doubt their experience. For my part, I don't think I could A/B a difference between any of the tube gear I've heard or owned that was left on for, say 40 minutes, or even 20 minutes, and gear left on for two hours, or three hours or more. Dead cold vs. 20-minute or half hour warm up, sure. And unlike say digital clocks, which may take a while to reach thermal stability and may change performance with relatively small changes in temperature, I'm not sure the tubes are behaving all that differently after 8 hrs vs. one hour.

But I definitely agree with people who say it's a bad idea from a safety POV to leave tube gear on unattended. After 30 years of playing around with tube hifi and tube guitar amps and the like, I've seen too many tubes inexplicably start drawing too much current, or things like bias resistors just fail suddenly, or rectifiers arc, to think its a good idea to leave the gear running unattended. It's also a horrible waste of energy, if anyone cares about their carbon footprint or electric bill or whatever. Yeah, I've never seen a preamp running only small twin triodes fail spectacularly in the same way I've seen power amps fail, but why risk it?

 

Well, in my case these are battery-powered devices so their current draw is extremely low.

Has anyone ever heard of preamp tubes failing spectacularly?

 

There are WAY too many factors weighing in favor of turning off tube gear when not in use: preserving the useful remaining life of the tubes; safety; energy conservation; and preserving the life of the non-tube components in the tube gear (heat will shorten the lifetime of other components, particularly capacitors and resistors. I have not seen a spectacular failure of a tube unit that would raise safety concerns, but, why take unnecessary risks? Also, if the tube preamp is connected to an amp that is also kept in operating condition, a failing tube could send some nasty noise down the line that could damage other gear (or annoy the neighbors if left unattended).

The upside of leaving gear on all the time--perhaps better sound--is subject to the laws of diminishing returns: beyond a certain point, say 20 minutes of warmup, there is a small increment of improvement at the high cost of loss of remaining tube life, etc. After not that many months, the loss of performance from the tubes becoming weaker will FAR outstrip the benefits of the gear being fully warmed up. This is the case even with the small signal tubes in a preamp that typically have a longer life than output tubes. I would not waste tube life even if I only ran lower cost tubes (like the $4.50 12B4s in my Emotive Audio Epifania linestage), and I am particularly concerned with wasting tube life with my other gear that runs pretty exotic stuff (like the four 348s and four 349s in my amp).

 

I do think it depends on the device. I used to use a Lamm L2 Reference line stage, which is a bit of an odd duck- solid state audio path, tube power supply. That thing really liked to be on all the time, and Vlad recommended doing so; you'd replace the PS tubes once a year; no big deal. (Though I was always concerned about lightening zaps, and did unplug during heavy electrical storms- took days for that thing to come back 'on song').
My amps, Lamm ML2's (the older iteration of his SET amp) takes at least 45+ minutes to start to open up, and it keeps getting better for hours. A half hour isn't enough- it sounds a little flat, less dimensional, less "full bodied"- then it gradually starts to do its magic. I don't leave 'em on all the time.
I think I posted a link (somewhere here on the site) to an interview with Sears, the guy who owned that studio in Manhattan famous for a lot of tube gear. (He died a few years ago, but as far as I know, the studio is still going gang-busters). He said he never left the stuff on all the time, for a variety of reasons. (I can try and find the link if no one else has it).

 

I agree. My cd player sounds great after being left on overnight. I usually turn my tube stuff for about an hour before I listen to it.

 

Of all my amps my Almarro 6c33c sounds much better after being on for over an hour.

 

The only place I'd leave tubes on 24/7 is in a brick house. Otherwise one spark and the wood house goes down the tubes.