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Valve amps: when and when not to leave on.

Brian S

pfm Member
There seems to be no general agreement on this. I play music for a few hours morning and a few hours evening and never can decide should I, or should I not, turn off the amp.,. Is there any expert advice on this?
 
This question has been asked on several occasions.

I wouldn't leave any amp on and unattended. If it's a valve amp you are wasting energy and using up the life of the caps and valves. They generally get up to speed within 20 minutes anyway.
 
This question has been asked on several occasions.

I wouldn't leave any amp on and unattended. If it's a valve amp you are wasting energy and using up the life of the caps and valves. They generally get up to speed within 20 minutes anyway.

This, there is no point in leaving valve amps on if not in use, it`s just a waste of energy and and valves.
 
As someone who once kept his upper Naim kit on 24/7, I certainly wouldn't leave my power mono's, pre. or CDP on for longer than necessary.
 
As above, never. I find both my Stereo 20 and Verdier valve preamp both sound great from cold. I don’t leave the solid state stuff on either. To be honest if something sounds obviously wrong from cold it is either broken or a very poor design IMHO.
 
The fussiest valve amps I ever owned (SET monoblocks), did like to get warm first (just like brenda clamps, of 3, the larches (apparently)) but even they only took 10 mins. Valves have a finite life...could be as little as 1000 hours, probably a tad more more, but why chuck away 5 of those a day for nothing, not to mention the large energy wastage. Waste 5 hours a day and you'll need new valves within the year...madness.
 
To be honest if something sounds obviously wrong from cold it is either broken or a very poor design IMHO.

The Aleph 2's do take about 30-60 mins to come on song and sound bloody awful for the first 15 minutes, I generally get home, switch on the amps, get changed etc and then come back to listen.

I left the Alephs on overnight by mistake and came downstairs in the morning to find they'd melted the brickwork.
 
I would not leave a valve power amp on and unattended even to go the toilet...

When they catch fire it is a very stressful experience - I know it happened to me and I was in the room at the time.
 
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.
 
I would not leave a valve power amp on and unattended even to go the toilet...

When they catch fire it is a very stressful experience - I know it happened to me and I was in the room ate time.

The wife of a friend of mine turned on his Quad IIs and opened the patio doors so she could listen to some music while she did some gardening. After a while she realised the music had stopped and went to investigate. She discovered a dead amp with a seriously burned out mains xfo and a rather dramatic Rorschach test design on the wall made from squirted-out liquefied potting pitch.
 
The wife of a friend of mine turned on his Quad IIs and opened the patio doors so she could listen to some music while she did some gardening. After a while she realised the music had stopped and went to investigate. She discovered a dead amp with a seriously burned out mains xfo and a rather dramatic Rorschach test design on the wall made from squirted-out liquefied potting pitch.
Bloody hell! I 've just left the grill unattended whilest keeping an eye on my amp.
 
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).

Vintage amps are as good as the specific servicing and condition. They wouldn’t have lasted 50-60 years and still be highly prized if the designs weren’t sound, but manky old caps, resistors etc can be dangerously off spec if original. Even though rebuilt to an OCD/perfectionist level I’d not leave my Leak Stereo 20 unattended for longer than a quick toilet break (where I can still hear it) as the fuse protection on these is pretty rudimentary and whilst they are reliable if they do go wrong they tend to go wrong pretty fast! By saying that they were designed to be stuck out of sight in a wooden ‘radiogram’ type cabinet and countless numbers seem to have survived to this day. Anyway I’m rather paranoid about making sure the Leak is off after I’ve stopped listening.

Back when I had a little Decware Zen SET in my TV rig I did twice forget to turn it off, once I left it on over night, the other time I actually went out shopping! No issues and it was well fuse protected so I assume it would just have popped one if a tube failed. Its one reason I got rid if it, I want something far simpler on TV duty so I’m currently using a little Amptastic T-Amp which I often leave on for most of the day.

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.
 
I would not leave a valve power amp on and unattended even to go the toilet...

I have to poo poo that one ! My amp's are designed to be left on for long periods (as originally designed for studio use), and certainly should not be turned off and on in short durations
 


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