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

Don't tubes draw the same amount of current at all times when they are biased correctly?

No

whether or not it is ok to immediately play the amp after switching it on

It won't hurt it. It just won't sound right.

My experience with tube amps is that they tend to sound better after some warm up...same with ss amps. One of the things that I always wandered about when I was using tube amps was where in the life of the tube ( power tube) was I listening. I had an ARC and then a Melos and with the Melos, the power tubes would fail often; Sometimes in spectacular fashion. The quality of the tube was a major factor as far as the life and sound of the tube was concerned. With some of the Chinese tubes, the lifespan was maybe a few days or less! One of the issues I still have with tube amps is the heat they tend to throw off, however, after having lived with ss now for more than ten years, I personally am willing to add a tube amp for the difference in performance they provide. But, I still will use ss for my peace of mind.

Don't tubes draw the same amount of current at all times when they are biased correctly? Otherwise biasing would only matter when the amp is not playing.

Thanks to all.
Viridian, Herman & Atmasphere - seems like you all agree tube life in Class AB amp service is affected by volume level. Guess I'll look into buying some spare tubes!!

Dpac 996 - Don't know what ill effects cranking things up prior to full warm up might have. BUT I too hear an improvement after things have been running a while. Seems a common experience with tubes - but I also thought that with a solid state receiver I ran in the past - the sound opens up. After 1 hr for sure...but I think after a few hours, there is another step change. No quantitative data to back this up - just an overall impression.

Good listening to all.

Don't know the answer either, but would like to ask whether anyone knows whether or not it is ok to immediately play the amp after switching it on? I seem to recall reading somewhere that a tube amp should be allowed to warm up a few minutes before receiving a signal...

If your amplifier is class A, the volume setting will have little effect on tube life.

With any other class of operation, the higher the volume setting, the shorter the life of the tubes, although other factors such as the actual bias level of the tubes, how optimally they are loaded to the speaker and how well ventilated they are can play a bigger role. It all makes a difference.

Generally speaking, the warmup you hear in a tube amp has more to do with the tubes and the filter caps in the amp than anything else. Most tube amps are doing fairly well after 45 minutes and most have gotten to where they are going by about 3 hours.

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.

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.

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.

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

Thanks all.
Kehut - yes, I agree on the dangers posed by over-driving and clipping. That hasn't been an issue so far even though I'm driving Totem Forests (not very efficient) with a Jolida 502B. Good news there from what I've read is that the Forest's impedance curve doesn't drop all that low. (as a side note the only CD where I thought I was starting to get some distortion is the Stones, "A Bigger Bang"...that is a loud recording and I usually have to back off the volume on that compared to some older CDs.)

My practice too is to turn on the amp 30-60 min before I sit down to listen. Sometimes I'll play a CD on repeat while off doing other things. Seems like the amp warm up result is different after a period of simply being on vs having "worked" during that time. FWIW I also unplug my equipment when not in use.

I don't know what class of amp my Jolida 502B is or what the various classes mean...I can certainly research that but if anyone feels inclined to summarize - that would be appreciated.

I'm not sure there's a concensus here about the original question. Intuitively, it seems like playing louder would work the tubes harder but I'm not a an electronics engineer. I suspect its true as several have noted, differences in hi-fi/home listening volume levels won't have a significant impact on tube life.

Thanks again.

Kehut

The amp would only draw full rated current from the power supply if operates in Class A. All single ended amps are class A but few others are. Most operate in Class AB and draw much less current at idle than when driven.

I know from experience that power tubes in guitar amps have shorter life when routinely driven hard. I think the same will be true for high fi tube power amps, though the conditions in most hi fi amps are much less severe than in the average guitar amp.

Beavis
Question.How do you know you are at 85db when listening?Do you use a meter?If so why?I suspect for safe hearing levels but I like to hear your reasons!
Regards
George

After further thought on this, I recall an article that said the power output devices in an amp are running full tilt all the time and the source/preamp is what controls input. Or something like that.
Which at one time some cd players with volume control didn't have enough output voltage to drive an amp to full power.

I believe that when a tube amp is at idle, it draws full rated power/current. Increasing volume doesn't draw more than its rated power...however, it can drive the amp to clipping, which can be detrimental to the life of the tubes..especially tubes that are worn down, and don't hold their bias.

I see ads for equipment here all the time saying that the equipment "wasn't driven hard". Well does playing and amp and preamp very loud cause it to age prematurely? Is is better off than an amp or preamp that wasn't played loudly?

I'm not posting this to start an argument. I equate this from a mechanical view.Consider the life of a gas powered motor vs. a diesel motor.Higher rpm's equals shorter life span.Simple idea.
A good question. If we could get someone that absolutely knows the answer,it would be great.

I've heard whenever a tube is on the clock is ticking. That's why I've heard that if you know you're not going to be listening for the next couple of days to power down tubes. I take it one step further with the modern tube gear I own & power down tubed equipment after each usage & allow to warm up for one-half to one hour before listening. I have not noticed excessive tube wear.

But I must be honest, I don't know if listening volumes affects tube life. I suspect it doesn't, practically speaking. I usually listen at 85dB.

Sounds like a good question to me. And while I've used tube equipment for over 35 years, I admit to not knowing either. What I am reasonably sure of is that for a typical Class A/B circuit, how loud you play will not have any practical impact on the life of the tubes. The impacts of proper biasing and the designer's decision on how hard to drive the tube within the circuit will overwhelm any impact we can have as users in just playing music through them.
.