I’m relatively new to tubes in my hifi setup. Recently went from SS pre to tube ARC pre-amp and a Croft phono stage.
I have always kept all of my SS gear powered up 24/7(and still do), but I shut down my pre-amp and phono stage now after I am done listening for the day. I power them up at least a half of an hour before I put anything into play.
I would prefer to leave my tube gear on all the time, but am concerned about premature tube wear.
I have a Croft Micro 25R pre with phono stage and have used tubes for years. You do not have to leave them on. While they do sound a little better once warm, it it not a major improvement. If you did, and assume 5000 hours on the preamp tubes, you would get 7 months. Power amps somewhat less.
I guess I'm the dissenter here. My modified CJ PV-12L is on 24/7 and my two 12AU7s have been in circuit for 18 months now and remain quiet and dynamic. YMMV.
My friend, an audio manufacturer, keeps his tubed DAC and tubed pre-amp on 24/7 during non-summer months, unless he knows he will be away from his house for a stretch. He is a proponent of 24/7, and says the power surge upon turn-on is harder on the tubes than 24/7 usage.
Assuming one listens to his or her stereo predominately on weekends, an alternative is to power up the non-power amp components on a Friday evening, and shut them down on Sunday night after all listening is completed.
My friend, an audio manufacturer, keeps his tubed DAC and tubed pre-amp on 24/7 during non-summer months, unless he knows he will be away from his house for a stretch. He is a proponent of 24/7, and says the power surge upon turn-on is harder on the tubes than 24/7 usage.
The above pretty much states the two ways of looking at the issue. I have read good arguments both ways.
My tube preamp designer said to keep it on all the time for best sound and tube life. He said turning it on and off is more stressful for the tubes in his design.
I don't think there's any one right answer to this question. It depends on how hard the component is on tubes, how long the component takes to "gel" from a cold start, time between listening sessions, how unpalatable (or conversely, inconsequential) re-tubing is to the owner, etc.
For example, my tube preamp (with internal phono stage) sounds great after a couple hours of warm-up. My tubed DAC, on the other hand, doesn't start to sing until it's been on at least 24 hours. As I'm primarily a weekend listener, I power things up on Friday morning before I go to work, ready for listening Saturday morning, and then turn things off Sunday evening. The DAC doesn't sound terrible after it's been on for an hour or so, but doesn't get the goosebumps going at that point.
Neither piece is hard on tubes (a long time ago I had an Audible Illusions
preamp that ate tubes for breakfast), and if either of these components were tube eaters my approach would change as I'm using some pricey NOS tubes. Finding out how long the tubes last in your pieces will take....well, will take until you need to buy new ones. :)
From a safety/power consumption standpoint there's nothing to worry about with a preamp or phono stage if left on 24/7. If I could listen every day as you do, I'd just leave mine on.
Short answer is NO with any model. Not only it's unsafe, but it's useless waste of tubes and other circuit components as well. It's a huge tax on component longevity.
1. tubes dissipate heat that dries out electrolytic caps. 2. occasionally blown tube can blow other circuit components or even set circuit board on fire. _______________________
tubes worm up a lot faster than transistors and caps 'fill up' with charge nearly instant. so what's the point running it on even throughout the night? turn on for 10...20min before playing music and enjoy.
In my experience, and apart from components that use Black Gate power supply capacitors, well designed tube gear will be "on song" anywhere from 1/2 an hour to one hour after powering on.
In contrast (in the dark days when I ran solid state amplification), I
heard subtle warm-up differences up to 96 hours after powering up my
amplifiers. Needless to say, I left them on 24 x 7 except during the two month thunderstorm season here in Colorado.
As far as component damage from running 24x7, I agree with the poster who referenced heat damage to electrolytic power supply capacitors. If you reference typical power supply capacitor specifications, you will find lifecycle ratings in the thousands of hours (5-12,000) at a temperature like 105 degrees Celsius.
As far as turn-on surge for tubes, this hotly contested, and most of the mythology stems from applying the good practices that relate to high power transmitting tubes (tubes that operate in the thousands of volts range) to consumer audio devices and guitar amps.
With tube rectification (typical indirectly heated rectifiers like the 5AR4), there's an inherrent delay in the B+ so the tubes come up to operating points gracefully.
Now if the designer uses either a directly heated tube rectifier or a solid state rectifier, all bets are off, and they should have a soft-start/muting circuit to delay the application of B+. If they don't, then they'll stress the tubes each time they power them on.
1. tubes dissipate heat that dries out electrolytic caps. 2. occasionally blown tube can blow other circuit components or even set circuit board on fire.
1. So do transistors 2. I've owned tube equipment for 25 years and have never had a tube "blow." I've never even seen one on TV. And should a tube go into thermal or current runaway, there are fuses or sacrificial resistors to shut off the juice, at least in modern and properly designed units (in which category both of the OP's components fall).
Any component can fail, and I'm sure there are cases of spectacular failure. But that goes for both tube and solid state and is the exception. Cars can catch on fire too. Most don't.
The tubed ARC pre should be fine left on while you are out of the house, but ARC power amps definitely and absolutely not. Their power tubes aren't fused, and when one pops the amps have been known to burst into flames. As I am most likely about to be ;-).
1. transistors in most class A/B and class D amps don't and there are many class A/B amps that don't run hot. 2. I've repaired tube equipment with burned circuit board around blown tube more than once and for me one is too many anyways.
Old saying says -- No problem till the SHTF. Right?
and says the power surge upon turn-on is harder on the tubes than 24/7 usage.
This really has to do with the design! The phenomena known as 'cathode stripping' really affects power tubes a whole lot more than small signal tubes!
I find that I get much longer life out of the tubes if they are only on when I'm using them. After 20-30 minutes they sound great and after about 2 hours they've gotten as far as they are going to go. Running a tube preamp 24/7 is going to shorten the effective tube life unless you work at home and have the stereo playing all the time.
It depends on preamp design as stated above but Audible Illusion tube preamps have their tubes lit even after the power button is off. According to Audible Illusions this lenghthens the life of the tubes.
if you are breaking in equipment also do not leave it on 24/7
patience is a virtue and you will be rewarded soon enough
I have a friend who will not sell any of his NOS tubes to a guy who will leave them on 24/7 just to see those famous blue lights shining behind the face plate glass
@audiotomb, I understand a concern of vintage NOS tube dealer, but at the same time you never know if one will be running them 24/7 non-stop, but according to most of contributor's here with "deep experience and knowledge", some, as turn out, definitely will...
I've yet to see a signal tube explode! For that matter its really really rare even for a power tube.
I've been servicing consumer electronics since 1974. I've yet to see a fire in **any** preamp, tube or solid state that was not caused by a lightning strike. Not saying it can't happen; I **am** saying that it likely will not be caused by a tube.
A tube power amplifier is a different matter. Power tubes can arc and cause associated resistors to heat up and fail (these days, responsible manufacturers use 'flame proof' resistor types in those locations).
But we're not talking about tube amps, we *are* talking about tube preamps.
Well, some ARC tube preamps can power up a pair of small speakers if connected to the output to significant SPL levels. That is to say that signal tubes there are driven rough almost just like power tubes. PCB might not catch fire, but it might burn 'foil side' that in places will need to be either rebuilt or point-to-point wired. Once again, the possibility of failed signal tube to affect other circuit components as well as PCB is there.
Thanks for all the comments from both sides of the question.
I have left them on for the past few days, but I think I will revert to the way I was doing things before. Power up 30 minutes before listening.
Since I have been leaving them on, and away at work during the day, I have a constant nagging feeling about them being "live" while there is nobody at home. Piece of mind is going to out weigh any sonic advantages.
I have seen a few tubes go out with a bang but never explode. My TVA-1 used to destroy Mullard Osram KT88s - plate red hot and some sparks then a fizzle and a pop from the speakers!
It's not even about tubes, It's about TEMPERATURE and the length of exposure to such temperatures. Speaking of ARC tube preamps YES they run hot! A faulty DC capacitor can cause excessive bias current and destructive heat that can cause PCB go to flames.
As I've mentioned prior, one is too many, but repaired more than one. Running units 24/7 in simple term mean you don't give your circuit elements a 'recoil' time to recover after applied heat. Shortening life and paying extra for the idle time. That's where simple math shoves all the science behind.
Well, some ARC tube preamps can power up a pair of small speakers if connected to the output to significant SPL levels. That is to say that signal tubes there are driven rough almost just like power tubes.
I have a set of adapters to use my preamp with my speakers in case I don't have a power amp to use at the time. The preamp (MP-1) will play my speakers with about the same volume a type 45 SET. But the tubes aren't run that hard and last for years without any degradation of the circuit boards even after decades of use.
What you are saying here suggests that such is a different matter with ARC preamps. But I think if that were really a serious problem we would have heard about it by now! Preamps bursting into flame is a pretty unusual thing and the age of the Internet has been with us for 24 years!! And no such reports. So I think we can regard this as a 'theoretical' (or perhaps more accurately as a Red Herring) rather than an 'actual' and only applying to certain ARCs, which, if true says more about them than tube preamps in general.
But I do find myself doubtful about this idea- I have friends that work at or have worked at ARC for many years (I live in the same town and knew them before they went to work at ARC) and none of them have reported anything like this (and they would have if they'd heard about it) so I just don't think this is a concern.
There are only so many electrons in a vacuum tube. The longer you burn the tubes, the shorter their lives are going to be. You can expect to wring about 10k hours from pre-amp and driver tubes, and about 3k hours from power tubes. An important issue is how you bias your power tubes. That will have a major effect on their longevity. Yes, a lower bias in a class A/B will create a lower transition to Class B, but you probably won't hear it at lower volumes. This is not an issue with signal tubes used as drivers and in pre-amps: they are running full-tilt all the time regardless of volume and tone settings. The volts applied to them will affect their lifespan, but that's not something you can control from the front panel.
Well Atma is spot on as usual. It depends on design. The tube preamp I have owned for years, TRL, ran barely warm and was a better climate for the parts inside. The designer always told me to keep it on unless traveling for days etc...
This actually led to better sound, happy internal parts, and longer tube life according to the designer.
I have never heard of a tube preamp catching fire and Atma's comments cannot be improved on.
I run a couple of hybrid amps and both have circuitry that allows the tubes to be turned off when you switch to stand-by mode. It means a delay when you fire it up again, but not as much as if you turned it off completely. One is an Audio Research and the other is a CJ Premier.
Keeping your tubes fired up all the time will drastically shorten useful life.
I have a Rouge integrated amp with stand-by soft start. Truthfully, after a half hour warm up it sounds great and additional hours of warm up seems to make no difference, so, except for periods when I plan to listen to music for a couple of days in a row (even then usually turn on in the am and off at night unless on an all night music binge) I see no point in leaving it on 24/7. I also have a Audible Illusions Modulas II preamp, also with a stand-by soft start and left it on continually only during periods of extended listening and off during periods of not listening. I had to change out the tubes only twice in 25 years. If your pre amp has a soft start and you listen to every day, I agree with paul79, on once off once each day.
I have a vintage CJ P-11 that's been modified. Since I'm retired, I listen most any time of the day. So, I leave it on all day and turn it off at night. I used to turn it on and off and had to wait annoyingly each time I wanted to listen to music. I'm much happier this way, but am I doing it any harm? i dearly love the unit.
There are only so many electrons in a vacuum tube.
There might be a limit to how many electrons can **flow** through a vacuum tube... I've seen some 6SN7s go over 50,000 hours in our gear. Admittedly, that's an outsider number but some tubes have very long lives!
I'm much happier this way, but am I doing it any harm?
Don’t have much to add here, as about everything has been said!
For me, I turn off all of my tube gear (4 power amps and 3 preamps) when I don’t plan to listen to it within the next 2 hours. To my ears, all of my tube gear sounds great within 10-15 minutes of powering on. Some say an hour, I just don’t hear any difference of 15 minutes of warm up vs 60 minutes. The temps inside the tubes are pretty warm within 15 minutes.
I do know a guy who runs his preamps 24x7 and has for about 10 years now. Over 150,000 hours on his tubes and they still test as very good. I also know people with tube preamps from the 60s which still have their original tube sets in them - not run night & day for 50 years, but used a lot along the way - and powered on and off thousands of times. Some tubes do have very long lives!
Personally, I've never had a preamp tube burn out so I don't know how long they last.
I've notice even if I leave my pre-amp on all day, it takes about 30 minutes of playing music (especially the phono side) before it really kicks in. I see no point in leaving it on all day now
After looking over this entire thread, it appears that the approach to this conundrum varies based on the preamp you have. Different circuit topologies must be kinder or less kind to the tubes when left on 24/7. Vive la difference!
According to the Department of Defense, a preamp tube meaning a small signal tube if played 24/7/365 will last about 22 years. At 8 hours a day, over 60 years.
It has been pointed out that temperature plays a roll here. It is not the tube that is in danger, but the other components. Heat kills capacitors (especially if your unit has 85c devices not 105c) film exception, and can weaken resistors even metal film ( wirewound the exception). The reason a 'designer' has suggested you leave something on is for thermal stability....everywhere has the same temperature, no cold/hot spots inside the device. Hot, cold, hot, cold also weakens or cracks solder joints.
All this applies to preamps. It still is a personal choice and how big your wallet is.
Power amps....no, no, no...period. Even 15 minutes is enough to get the temperature of the plates up to operational levels. Leaving a tube power amp on when you are not listening to music, is money in the bank for tube sellers. DOD rates power tubes at 3,000 to 5,000 depending how close to class A they are driven/biased from AB, and in class A the hours drop fast. This applies even in stand by.
Last, if you have a 'stand by' position for the amp, use it for the warm up as it keeps the B+ off the plates until temp is reached.
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