A question I suspect reveals a lot of ignorance...

Power tubes run in class A are maximally stressed at idle, so they will age pretty much equally if playing or not. Most preamp tubes are also run this way, so this holds true for them as well. Most tube amps outputs are class A/B and these are stressed least at idle, so the output tubes will age more quickly when playing music. If overdriven, as tube amps frequently are, they will age more quickly yet.

Could anyone comment on the sound effects you hear as your power tube amp warms up?

Also, what may happen if you start playing music loud with a tube power amp that has only been on for about 5 minutes (you know the impatient start to a listening session)

I recently got an ARC Vt100mkii and personally I have not noticed a difference after its been on for about 45 minutes. Up to that point, the sound seems compressed and the bass is not as developed (as it can be). But, this result still is not objectionable in any way, its just not optimal...

I think it is the low voltage filament that dictates the life time of a given tube. The filaments don't like the turn on stress: thermal/mechanical.

It would be nice if, like most tube guitar amps I have come across, high end home audio amps would have seperate switches for the filament (standby) and b+/plate (operate)

I wonder how much longer a tube in the same circuit would last if it was brought up to operating temp before the high voltage was applied. maybe none??

Great thread

There are 2 parts of the equation. The amount of power dissipated by the plate is determined by the class of operation as stated above. Class A amps like SETs consume maximum at idle and push pull amps minimum at idle.

However, in all case the filament and cathode is sitting there cooking away so even a push pull amp tube will eventually burn out even if you never pass a signal through it.

yioryos, your exclamation point made me wonder if you find some lack of credibility to beavis' assertion that he listens at @85db. i do not know why beavis mentioned this but many of us do own meters for kicks and also to conduct objective tests on overpowering amps as well as a myriad of other useful comparative tests. personally i think anyone involved in 'hi end' stereo sound would find it VERY informative to have a SPL meter laying around. they can answer a lot of sonic questions accurately and save a lot of time. just my 2 cents. i keep it next to my remote(s) and refer to it for kicks eg. if i decide to measure a loud passage to find out how loud it 'really' was.

A meter is critical for getting correct placement in your room for the smoothest spectral balance - especially important for get the bass right - but this is off thread. I think that tubes in Class A is not affected by loudness, other than clipping, and A/B is. Probably a good question to ask at Audio Asylum in the "Tubes" scetion.