Tube amps - leave on or turn off???

[kentamcolin]

I have an ASL MG Head/OTL tube amp and am wondering if it is best to leave the amp on 24/7 or turn it on and off as it is used?

[mkmelt]

It depends on how often you use the amplifier. If you use it every day and want it to be fully warmed up and ready to go at any time, then leaving it on may make sense.

If you use it only a few times a week or less, it would appear to be a waste of electricity and the useful life of the tubes to leave the unit on all that time in between sessions. With a small amp such as the ASL, the heat output of the tubes is minimal, not so with the larger tube equipment. In the summer this could make the room appreciably warmer than it would be otherwise, but nice and cozy in winter.

Some tube designs include standby circuits that keep the tube heater elements powered at all times, as this is less stressful to the tube when powering up the amp.

Small triode tubes such as 12AX7 and 5751 can last as long as 10,000 hours. Power pentode tubes such as EL-34 and EL-84 can last 2,500 hours. Tube life can be extended by several times if you use a small auxilliary cooling fan. I do this with all of my tube power amplifiers and receivers to try and extend the life of my tubes as long as possible as some are expensive and not easily replaced.

I don't leave my tube gear on all of the time, but I also don't power them up for only a short listening session as constantly turning this equipment on and off is stressful to the components. I like to have at least 2 hours of listening time if I am going to power up my Fisher 400 receiver. For shorter listening sessions, I have my solid state gear for listening to music. I am sure it stresses the solid state gear too, but it is better than wearing out a vintage tube set.

Except for my computer, which has a UPS power source and a cooling fan, I don't leave any appliances on when I am not home during the day, and when I go away, I power off the computer and unplug all of my audio/video equipment in case of electrical outages and power surges.

[TravelLite]

The following snip from Cary Audio's FAQ strikes me as a good, but non-specific rule-of-thumb. Things like kids, kid's friends, and pets in the house might also factor in though.

When is it best to turn my equipment off?

This brings us to an ongoing debate. Which is better-leaving the product on 24 hours a day or turning it on and off? Both will shorten the life of your tubes. So what should you do? The answer lies somewhere between the two. If you listen faithfully for several hours a day then leave the unit on. You do not want to turn it on and off several times a day. This is worse than leaving it on 24 hours a day. If you listen two or three times a week or just on weekends, turn the unit off when not in use. In this case, allow one hour for warm up time. For the weekend listener, turn the unit on Friday and turn it off Sunday night. This will optimize tube life for your amplifier.

Source

Obviously, the use of a surge suppressor is good practice too.

TravelLite

[Magic77]

I've been debating this with my X-Can v2. Musical Fidelity says in the owner's manual that the X-Can is made to be left on "indefinitely". So, I don't think they would have put that in the manual if it were not safe to do so.

So, I'm assuming that the tubes in the X-Can draw very little power when idle.

[kentamcolin]

This has been really helpful. I don't often get the oportunity to listen for extended periods, maybe 1-2X per week. I do however take 15-30 min. once or twice a day, sometimes more, and for that short of time tended not to let the tubes warm up to much, and was concerned about all this switching on and off. I'll just leave everything on and forget about it, then my favorite system will always be ready when I am!

Thanks.

[ServinginEcuador]

Kentamcolin,

Do you have any replacement tubes on hand to replace in your amp?? I ask since you are deciding to leave it on and that means that your EL84 tubes are going to wear out in about 100 days of 24 hour usage!!! At that rate you're going to need about 3 sets of tubes a year to run the amp!! Not to mention the cost of a decent 12ax7 tube which will need replacement about once every 300-400 days of constant use!!!

The way I look at it, and this is only my perspective, I use my amp for about 4 hours a day, that means I leave it off for 20 hours, then turn it on and use it for those four hours once a day. It can not be too much harder on the tubes to turn them off and on once a day when compared to 24hr a day usage. Unless you can manage to install a switch that cuts off the high voltage to the tubes and just leave on the filament voltage??? I heard someone did that, and it would really extend the life of the tubes since they would only have the 6-12 volts applied to them and that would give you the best of both worlds!!

[Sovkiller]

Unless you don't have a heater home during the winter time, I would not leave it on all the time, what for? Do a simple math, if you sleep 8 hours and work or go to school for another 8, what is left about 6 or 5 hours, discounting the trasportation and lunch and dinner times, why are you going to leave it on more than 16 hours in vane, tubes are pretty expensive, so the electricity...

[tanfenton]

I warm my SHA-1 and Cornet (yay, it didn't take long to build!) up whenever I expect I'll have several hours to spend listening. I allow the Melos an hour to stew and the Cornet a half-hour more. Both are powered off before I turn in for the night.

Warm-up helps with most of my tube combinations in each of the amplifiers, moreso with the Cornet which is why I give it some additional time to sweeten.

NGF

[mkmelt]

Assuming the bias current is not set too high, I think that an idling tube will last many times longer than one in use. Yes, you are boiling off atoms from the cathode, but not at a high rate when the amplifier is only powered on.

Anyone?