When to power off a tube amp?


So I just got new tubes for my Lyr and really don't want to damage these tubes and want them to last for as long as possible. So I had a few questions and was hoping you guys could help me, thanks.

1) Should I turn off the amp if I am going to away for like an hour or so? Would that decrease the life of my tubes more than leaving it on that whole time I am not using them?

2) Should I let my tubes warm up before using them? If so, how long should I wait?

3) Is unplugging my headphones before turning off my amp necessary?

And just a random question out of curiosity, what if you use two different tubes in a tube amp? lol.

Thank you guys, any help would be much appreciated.
highrolller
Hi High roller
Really depends on the types of tubes you have.
I run 300bs, and if I am leaving the house for what I think will be an hour(which is always more) I turn it off.
In contrast, my phono pre has 6dj8s which don't like being turned on and off, so when I flick this unit on, it stays on till I go to bed. I think tubes like 6sn7s could likely be left on 24hrs a day for 5 years before they needed replaced, so again it depends on the tube and its relative characteristics, cost etc.
I think question two is debateable re tube health. I would let the system stabilize(a couple to a few minutes. There is debate re sonic improvements and temperature of components. I don't want to go there since your question was for tube life. Power tubes heat up pretty quick. I also don't think tube amps are generally that fragile. Ie they are designed to be used, not only looked at.
Question 3: I would leave them plugged in and save wear and tear on the plug.

Cheers
Rob
Hopefully Ralph (Atmasphere) or Gary (Hifigeek) will weigh in. My practice, FWIW, is that I will leave my amp on unattended for up to 4 or 5 hours -- never if I am out-of-town.

Seem to recall that it's a bad practice to shut a tube amp off and then restart it unless waiting for at least 5 or 10 minutes. The "wear and tear" of a tube as I understand it is the tube's innards responding to hot and cold, which in turn, causes the innards to expand and contract.

Tube failure also occurs because of arcing. I do not know what user-related factors (if any) cause arcing. I for one would love to hear back from Ralph or Gary.

Bruce
1) Turn it off
2) Don't need to warm up before playing
3) don't need to unplug headphones
4) You can use different brands of the same type tube without harm
Alan
I would agree with Elizabeth. I was listening to music late one night and had fallen asleep in my listening chair. I was using VTL MB250 monobloc amps powering Maggie 1.6's. Something stirred me and when I opened my eyes I saw a shower of sparks coming from behind my right channel amp. It looked like a 4th of July display with all the sparks shooting in the air. I plucked the cord out of the wall and once I regained my senses saw the fuse holder for the B+ was charred.

I sent the amps back to VTL and was told the voltage rating of the fuse holder was too low and had caused the arcing. They replaced both fuse holders with ones that were physically larger at no charge.
Bifwynne:
Tube failure or arcing (flare up) happens in nearly all cases when the amp is first turned on from cold. This is because the HT comes onto a cold tube.

One way to rectify it is to get a 30sec delay circuit for the HT, so the heaters have a chance to heat the anodes and cathodes first. If you cannot build one yourself then there are many pre-made ones to insert on the HT rail.

Just Google or look in ebay for "Relay Delay Circuit" Do the math as you have high volts small current to give the relay contact amp rating you need. They can be bought for around $10 ready made. In the case of mono blocks you need two.

Or if this is too much bother, then just have another manual switch which breaks the HT so you can bring it on 30sec later, after the tubes have warmed up.

Cheers George