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Valve amps: when and when not to leave on.

You should leave on any amp that takes (say) a week before it reaches its optimum sound. You will be able to hear this for yourself. The opinions of others are not relevant.
 
Turned my Rogue Audio monoblocs on, went to pick out a record out and smelt something burning......one mono with flames coming out of v3 & v4. Coupling cap failed! Had I been out of the room.....!!!!
 
Brian S said:
Certainly pleased to hear a concensus on this. It has been my practice to turn off for any silent period of more than an hour and a half. What prompted my question was a claim that Audionote advised leaving amps on, and that turning valves on and off, due to expasion and contraction, reduced longevity. The writer's own practice was not to turn off between sessions.
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That may well be true, but I would err on the side of safety. The energy saved will go some way to off-setting the cost of more frequent valve replacement.
 
Brian S said:
Certainly pleased to hear a concensus on this. It has been my practice to turn off for any silent period of more than an hour and a half. What prompted my question was a claim that Audionote advised leaving amps on, and that turning valves on and off, due to expasion and contraction, reduced longevity. The writer's own practice was not to turn off between sessions.
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Valves are most likely to fail at switch on/off which is why It was common practice back in the day
to leave industrial valve equipment powered up for lengthy periods. Having said that, I don't leave my kit on unattended.
 
Anyway I’d expect anything decent and fairly recent (Audio Research, McIntosh, Conrad Johnson, Audio Note, Luxman, Leben etc etc) to be perfectly safe if in good condition and stuffed with decent valves.
There's the problem, what is decent? I wouldn't go out to make a cup of tea and leave on CJ or AR. I've had loads of these heaps in with burnt out circuit boards and nasty overheating faults. On the other hand I'd no worry too much if I went on holiday and forgot to switch off the Leben. It all comes down to the design and how stressed the parts are.
 
Tony L said:
One would sincerely hope good condition modern valve amps would be perfectly safe, i.e. have full and well-designed fuse protection. I’m sure most are, though I’m very wary of some Chinese models that are obviously only designed for 220V and run dangerously hot (e.g. grey-import Ming Da which very regularly blew up). (...)
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My valve power amp was modern and had received a rave review in HFW; it was running on 230V in France when it caught fire - no protection at all for power valve failure.

And power valves will fail! This is why there is nothing bigger than an 6SN7 in my system.
 
Should we distinguish here between pre and power amps?

In the manual for my solid state power amp it states that it can be left on without detriment (except to my electricity bill and capacitor life).

My valve pre is CE certified and presumably doesn't make huge demands on the valves. It's been serviced by a reputable EE in the last 24 months.

I quite often leave them both on for an evening because I want a one-hour listen after a night shift and want to hear them at their best. The power amp is definitely at its most transparent / liquid after an hours warm up.

Not sure I'd do that if the power amp was stuffed with glass...
 
The only difference I hear on leaving the amps on for a certain time is that the power amp transformer hums a little less when warm.
 
Mike Reed said:
No idea, but it sure as Hell stresses things by repeated switch on/offs (see post 27).
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Depends on the design. Some valve designs have slow start circuits to prevent any stressing. The valves in my designs (both pre and power) last for at least 10 years. I've had a couple back for servicing recently that were 20 years old and still with the original valves fitted. The valves still tested OK but I fitted new ones, so its good for another 20 years...
 
Had a PrimaLuna that went seriously pyrotechnic at the base of one of the power valves. Once fixed I couldn't have it on and not attended - too aware of how quickly it all happens. Croft (hybrid) now and happy leaving the little input valves alone for a bit.
 
I expected more from an audio forum, seriously. It's the cables, not the amp, that require warming up. Quality cables take a minimum of 12 hours current flow to reach peak delivery capability.

However, a little trick I learned helps speed that up. Since any decent cable is directional, if you orient them backwards they'll warm up in 6 hours rather than 12. It's from all the confusion inside the cable due to the asswards current bouncing around inside the cladding causing increased friction and sonic malfeasance.

But don't forget to turn them around the right way before cueing up the tunes. Which, of course, means turning the amp off and going through the entire process all over again. The upside is the money this saves from not buying music!
 
When I owned Naim kit I turned it off after use. I still liked the sound. Now I do the same with my valve-based EAR kit. Tim said not to keep the EAR 516 on all the time. My pre - an EAR 802 - gets hotter than any preamp I have owned so I turn that off too.
 
Anyone ever own a component without a power switch? And I don't mean it being mounted on the back with evil intent. No, I mean no power switch. I wrote a small manufacturer about this and he stated that the current drawn while not in use was negligible. I countered by saying that, yes, perhaps that's so, but the glow from the ridiculously bright power LED turned the box into an expensive night light. He then suggested a power strip, and jokingly said that the light being on should remind me to switch off the strip in event of a storm. I stared at that line in the email for a good half a minute before proclaiming it ludicrous. Interestingly, and I'm certain nothing to do with that exchange, all of his components were later adorned with a power switch. First on the back, then the front.
 
Just because a power switch is on the back does not mean anything should be read into that. It's best to switch off all kit when not in use and especially valve power amps, which with 400V or more (1000V in some extreme cases(, and quite a bit of current behind it, can really go ballistic if they go tits up.
Naim gear is an exception of course and should be left switched off 24/7 :D
 
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