Leave on or turn off?

Which is better for tube/component life? Turning the amps on and off with each listening session , or leaving them on all day? I typically switch them on when I'm having my two morning coffees, very relaxing start to the day. Usually in the evening I indulge in a longer session. Honey do chores etc in between. I'm assuming cold/hot cycling is harder, so I just leave them on all day. Yea or

LeGrace wrote:Which is better for tube/component life? Turning the amps on and off with each listening session , or leaving them on all day? I typically switch them on when I'm having my two morning coffees, very relaxing start to the day.  Usually in the evening I indulge in a longer session. Honey do chores etc in between. I'm assuming cold/hot cycling is harder, so I just leave them on all day. Yea or

WOW!

The short answer is: It depends.

a) As with any filament based equipment, keeping the filament hot reduces cycling stress. And, as with standard incandescent lamps, such (filaments) will last very nearly indefinitely if not cycled.

b) But a vacuum tube filament is not a standard incandescent filament. Most (but not all) are thoriated tungsten. This helps increase emissions, makes the filament more rugged, and adds to overall filament life. If not treated with Thorium, the filament will be treated by something else.

c) Those of us in the radio hobby are well-acquainted with something called "lazy cathode syndrome". This applies most specifically to early tube FM radios, and even more specifically to those using the 19T8. Back in the day, when FM was a novelty most users did not use the FM function all that much. Meaning the section of this tube dedicated to FM would be hot, but not being used. And that would contaminate the cathode such that it would no longer receive on FM, even though the tube would (usually) test well on a simple tester. And, those musicians that use tube amplifiers left on on "standby" mode for long periods would find deterioration in performance as a result of lazy cathode. Filaments are hot, tube is not in use.

So, the much longer answer than "it depends" is based on your particular situation. Short-cycling does kill incandescent lamps. BUT, an incandescent lamp filament is under far more stress than an audio tube filament, at least one of modern (post 1940) manufacture to the present day. So, very-short-cycling (<5 minutes) is probably not a good idea on a regular basis. But, it would be my advice to shut down any piece of tube equipment that will be idle for more than an hour absolutely, half-an-hour very probably. And, of course ABSOLUTELY ANY piece of tube equipment that will be left unattended *must* be shut down.

Well designed components with properly specified parts will not suffer, either by being left on, or turned off. So, your focus should be on tube life. And, keep in mind that an open filament is very, very seldom a failure mode for a modern audio tube. Back in the '01A/2A3 days, perhaps. But not so much now.

Seeing the other answer, here is an "add": Given the functions of an audio output tube, typically a pentode, pick any one, I would expect to see functional deterioration at-or-less than 12 hours of quiescent operation, probably considerably less. However, that deterioration *should* be easily overcome by a few hours of hard use - there are techniques for 'rejuvenating' tubes with lazy cathode, and heavy use is one of them. But this applies only after relatively short periods. I would expect that, say.... 24 hours of quiescent operation would create some permanent loss of output, and that this loss would increase logarithmically as quiescent operation continued. So, tube life under these conditions is an equation with three variables: Time of use, Time of quiescent operation, and output. Not a linear relationship between hours of Hot Filament and output only.

Nay!  On 24 hours per day a power tube with 2000 hrs life expectancy is just a mere 83 days.  Spending $200 for power tubes 4x per year does not sound like a good plan to me. 

I listen about 20 hours per week and that is only 1000 hours in a year's time.  There are other things to consider like electricity cost and unattended operation.  If I make short trips or very brief errands though I sometimes leave the amp on to save warm up when I return.  But unattended operation is never encouraged.

So I think you would end up spending more money trying to avoid power cycle mortality.

Rule of thumb for me?

Never turn your back on the bastids ...

Seriously, I never ever leave tube equipment unattended. I'll give mine a five minute warmup at most, and shut down after listening. Just too many things that can go horribly wrong.

Oh. Keep a fire extinguisher handy too.

sKiZo wrote:Rule of thumb for me?

Never turn your back on the bastids ...

Seriously, I never ever leave tube equipment unattended. I'll give mine a five minute warmup at most, and shut down after listening. Just too many things that can go horribly wrong.

Oh. Keep a fire extinguisher handy too.  

Never realized tube gear was so dangerous!!

I've left mine on all day. Fired them up in the morning, run to the grocery store, play video games on my other system, maybe watch some shows. Hours later I'll come back to my main rig and chill out or jam out depending on my mood. Some might say I'm asking for it but for the most part it's pretty safe. I built my ST120 a little differently with fused cathodes so if a tube blows it only takes out a fuse and not a resistor. Probably should fuse the B+ too but haven't gotten around to it.

I've got a fuse on my variac as well as a circuit breaker in another fancy power strip in the power strip line up. Lots of protection.

I do cut everything off before going to bed. I'm not completely insane.

corndog71 wrote:I've left mine on all day.  Fired them up in the morning, run to the grocery store, play video games on my other system, maybe watch some shows.  Hours later I'll come back to my main rig and chill out or jam out depending on my mood.  Some might say I'm asking for it but for the most part it's pretty safe.  I built my ST120 a little differently with fused cathodes so if a tube blows it only takes out a fuse and not a resistor.  Probably should fuse the B+ too but haven't gotten around to it.

I've got a fuse on my variac as well as a circuit breaker in another fancy power strip in the power strip line up.  Lots of protection.

I do cut everything off before going to bed.  I'm not completely insane.

I always turn mine off before sleepy time as well. Since I installed the GZ37's they just seem to be coasting along now and I just don't worry as much.

Always off. I also turn off the engine in my car when I run into Radio Shack to get my lifetime tube replacements. I turn off lights when I leave a room. I unplug my soldering iron when I leave my bench. I shut down my router and modem between internet sessions (that's not true).

I always turn out the light inside the refrigerator when I'm not using it.

(At least I think I do) ;-}

LeGrace wrote:

sKiZo wrote:Rule of thumb for me?

Never turn your back on the bastids ...

Seriously, I never ever leave tube equipment unattended. I'll give mine a five minute warmup at most, and shut down after listening. Just too many things that can go horribly wrong.

Oh. Keep a fire extinguisher handy too.  

Never realized tube gear was so dangerous!!

They aren't.  These guys are exaggerating a bit.  Otherwise you would have heard of countless stories of houses burning down during the tube era when people fell asleep with their TVs on, etc.

I agree that you shouldn't leave them on all day when not listening because you are just wasting power and tube life.  If you are not going to listen for an hour or more then turn it off.

.

corndog71 wrote:I've left mine on all day.  Fired them up in the morning, run to the grocery store, play video games on my other system, maybe watch some shows.  Hours later I'll come back to my main rig and chill out or jam out depending on my mood.  Some might say I'm asking for it but for the most part it's pretty safe.  I built my ST120 a little differently with fused cathodes so if a tube blows it only takes out a fuse and not a resistor.  Probably should fuse the B+ too but haven't gotten around to it.

I've got a fuse on my variac as well as a circuit breaker in another fancy power strip in the power strip line up.  Lots of protection.

I do cut everything off before going to bed.  I'm not completely insane.

I will take a chance, and be genuinely snarky in my reply:

I have been in this hobby since 1978 in a more-or-less serious way.
I have seen (at least) thousands of devices cross my bench then-to-now.
I would bet a significant number in any currency one might choose that few here actually understand entirely how to both pick and 'size' a fuse.
I have run out of fingers, toes, beard hairs and more counting those times when a significant part (usually a transformer) has released its magic smoke in order to protect that $0.30 fuse. Aside: I am having a transformer wound as we sit due to a poor choice of fuse. $192. I would have preferred to replace the 'correct' fuse and found the down-line problem first.

Turn off _ANY_ unattended tube-based equipment - this is partially a human life-safety issue, but mostly an equipment life-safety issue.
Exceptions would be if one is an Otis Elevator service person working with vintage collective-selective controllers. Those tubes (12AX7s, & 5U4s mostly) do get left on all the time.

Back when tubes were king in the television industry, I had a GE color television that had a feature called "instant on". When this was activated the heaters were on all the time whether the set was in use or not.  I tried it once or twice and when activated the picture and sound came up almost instantly when the set was turned on.  I never used it because I have to much Scotch blood and viewed it as a ploy by the manufactures to sell more tubes.  I make this point because there was a time when manufacturers were selling products with this very feature and never a word about caution that there may be a fire due to faulty circuits if left unattended and which never occurred to me that this could happen (I was much younger then and much more trusting).  I am now much older and wiser and one of those in the "Turn it all off when not in use corner".

Thank you, I'm convinced. No more leaving the amps on all day!

To quote tube aficionado Andy Bowman: "Don't turn your back on the bastards." Especially power amps. I'll leave the pre-amp(s) on all day if I'm in and out of listening sessions, but if I leave the house everything's off. You're just wasting electrons and putting wear and tear on the tubes.

Many times have left equipment running for days at a time. Why not? That's what it's for.

But I'd never leave the house without shutting things down. If only gone for a short errand I might leave the tuner on. I actually trust the older, restored gear more than a lot of the modern el-cheapo crap foisted on us these days - "power strips" anyone? CFLs? Automatic coffee makers? I'm pretty paranoid, if planning on being gone several days I shut off the water main, unplug just about everything not essential and so on. Ya pays yer money and take yer chances.

I admitted, some time last year, to leaving my st70 running for, iirc, weeks at a time. To the horror of forum members. Something eventually gave way, taking one of my beloved Gold Lion KT88s with it.

It was a foolish and reckless practice to leave that amp running. Good thing I was there to hear the hummmmmmm when things went awry. I might have been at work, just as easily, and who knows what might have happened if left unchecked.

I was duly lectured, and have not left the amp "burning" in my absence since.

Timely advice re "wearing out" LOL > just had my first KT88 power tube go south on me. Major scorch marks evident on the glass. Estimate after 1000 - 1200 hours. Had hoped to get at least a year. Lesson learned!!!

LeGrace wrote:Timely advice re "wearing out" LOL > just had my first KT88 power tube go south on me.  Major scorch marks evident on the glass. Estimate after 1000 - 1200 hours. Had hoped to get at least a year. Lesson learned!!!

LeGrace, what type KT-88 was it?

ArlanB wrote:Back when tubes were king in the television industry, I had a GE color television that had a feature called "instant on". When this was activated the heaters were on all the time whether the set was in use or not.  I tried it once or twice and when activated the picture and sound came up almost instantly when the set was turned on.  I never used it because I have to much Scotch blood and viewed it as a ploy by the manufactures to sell more tubes.  I make this point because there was a time when manufacturers were selling products with this very feature and never a word about caution that there may be a fire due to faulty circuits if left unattended and which never occurred to me that this could happen (I was much younger then and much more trusting).  I am now much older and wiser and one of those in the "Turn it all off when not in use corner".

A lot of TV makers had that "feature," including Sony, which burned a few houses down.

deepee99 wrote:

LeGrace wrote:Timely advice re "wearing out" LOL > just had my first KT88 power tube go south on me.  Major scorch marks evident on the glass. Estimate after 1000 - 1200 hours. Had hoped to get at least a year. Lesson learned!!!

LeGrace, what type KT-88 was it?

Genalex Gold Lion. May he RIP:



Changing tubes out every 5-6 months, if that's the norm, is going to hurt   ! Hopefully this was just a dud.

Looks like gas pains to me. Remind me to check my getter flashing to-day.

Not to be the least bit political - but do the most recent kerfluffles relating to Russia give one pause when considering tubes from that source?

I wonder what the throughput is - how long from factory-to-consumer?

I had a matched quad. Can I just order a replacement for Mr Burn Out? Or do I need to send one of the other ones back for matching? Or is not that critical?