If tube amp is left on, but not playing........

"A tube burns out quicker with no signal. Tubes work in the opposite of transistors - a transistor will pass maximum current at the highest signal voltage and the least current at no signal. A tube will pass maximum current at no signal voltage and the lowest current at the highest voltage signal. And, BTW, this is why tube amps should never ever be powered on unless the speakers are connected."

I don't know what you mean by that...but

Negative bias voltage is applied to the grid of the tube. As you reduce this voltage, the plate current goes up. And the tube runs hotter.

So you can run a tube near cut-off by raising the amount of negative bias. This tube will certainly last longer than one that is

(a) Biased hotter

(b) Run at consistent high levels

So for new guys, when you read the bias meter and you go from 50mA up to 60mA, the "idle" goes up.

You are reducing the bias voltage which keeps the tube "in check" and running the tube hotter and by some (small) degree shortening life.

Getting back to the original question.

Don't leave your all tube power amps on all the time. But don't cycle them on/off several tmes a day either.

check this page for stuff that may be helpful

http://www.upscaleaudio.com/rare/basics.htm

To Herman:

I hold an Amateur Radio license (though inactive now), and back in the late 60's early 70's just about all amateur gear was tube. The bigest cause of tube failure was considered to be thermal cycling caused by turn on/turn off cycles. Many hams kept filament voltage on to keep the temparature stabilized and just turned on B+ for operation. It seemed to work.

Dear Mr. Ghost Rider,

I cannot disagree. Your point about thermal shock is very real. That is why light bulbs almost always burn out when first turned on.

I think it all depends on how much the equipment is used. If you play your amps only on the weekends, then it probably makes no sense to leave them on all the time. If you listen all day long every day then maybe you should leave them on all the time. I have never heard a definitive answer, but perhaps someone here can site a study that will tell us for sure.

I turn my amps off when I am not at home or I am sleeping. I am more worried about fire than consumption of electricity or tubes though.