Howdy, I often pickup the guitar for 3-4 songs, put it down, do stuff and come back to it an hour or later. Is it better for my tube amp to be left on all day if this is the case or only turned on (and warmed up for a bit before using) each time?

It's better for your bills to switch it off from time to time. No standby switch on the amp?

What amp do you have?

A single ended class A doesn't like to be idle - the power tubes will wear out much faster. For a push-pull type amp it's not such a big deal tho.

In the long run your tubes will age a little sooner when you keep the amp on (idling) for long periods of time. But for the big capacitors it's actually better to let the amp sit switched on.

Your tubes will wear out quicker like that.Not to mention if you forget to turn it off and leave it on for 2 days,you could come back and find them dead.I've seen it happen,guy brings in a dead amp says I left it on for 2-3 days and it was dead.Power tubes were cooked and fuse blown.While your caps do like to se current on a regular basis to stay in good health,I wouldnt go as far as to say "for the big capacitors it's actually better to let the amp sit switched on".There are too many other things that can "over cook" if left on continuously for no good reason.I have a dozen or so amps,they dont all get used for long periods,I do power them up once a month just to keep the caps from drying out from lack of current going thru them.While it is better to use a standby switch to keep the tubes warmed up over the course of a couple hour gig situation,to leave it on all day to come back every few hours is not good.

As a part time amp tech for over 30 yrs, i fully agree with Stokes. Leaving tube amps on, even just in standby, for extended periods is not a good thang! Not only does it wear out the tubes, but heat will eventually damage other components, at least causing them to change value over time. It doesn't hurt anything to turn an amp on & off occasionally, but if you have standby, it IS better to just switch it to standby for a few seconds first. If you are just going to be away for a few minutes, it would be good to leave it on, but hours idling would not be good. I too have forgotten & left mine on for a whole day, right after changing tubes! It did wear them a bit.... arrrrgh!

Sez JMB

And heres a bit of a contradiction,beleiversblues.Leaving an amp on for a day with NEW tubes isnt such a bad thing.Burning in new tubes will help them settle in and stabilize the bias.Beyond that it is a bad thing.

Thanks for chipping in guys, I stand corrected!

I wouldnt say "corrected" michiel,more like "emended".Leaving the caps powered up is good for them,but can be bad for other things.

Great thread! Thanks. +1

Right. I should have specified that it's a new gen AC30CCX2 (PCB not handwired). It does have a standby switch. So what I've been doing by turning it on and off is the best thing - NOT letting it stand idle. I do let it stand idle (on standby) between sets at a gig but I imagine that's ok, keeps everything warm etc. I was a bit worried about the on/off hot/cold effect but I can see that extended periods of idling would be harmful. Is extended periods of playing more harmful though??

Standby is a MUST for idle single ended / class A amps. They can create a nice fire if you leave them on whilst doing nothing. They can't get rid of their "power that's ready to go" so such an amp can only cook your room a bit until it burns.

I have 2 hard and fast rules: If guitar is not in my hands then it is 1) in its' case or stand and 2) amp is on standby. Always - is pure habit now.

Just to be sure you're clear,dont leave it in standby if you dont plan on using it for a couple of hours.Standby is for situations as in a gig or a rehearsal situation when you take a break,half hour or so.

Sweet - cheers

Standby will give the high voltage tube parts some well deserved rest. So, use "stand by" whenever you take a break.

The filament glow thingies will still keep on glowing (ready to jump into action) and that's okay for the evening, better than switching them on and off all the time, but it's not good for days in a row!

Interesting thought, Stokes, leaving new tubes on for a while to let 'em burn in.... in working on industrial dielectric ovens which use broadcast tubes, we DID do that; never thought of doing it on an amp... anyway, it wasn't good for mine since it is a class a, an Ampeg Jet reissue.

Sez JMB

Rob, i assume your AC30, even being a newer gen is still a class a, so it would produce plenty of heat, even idling, so standby is indeed good for short periods. To me, the sound of a class a is better, for the most part, one just has to replace tubes more often.

Sez JMB

So, my Peavey Delta Blues runs 4 EL84s in push/pull class A/B operation. It has no standby switch, just takes 10 seconds from switch on to get to operating temperature and make sound. I don't leave it running if I'm not playing. Some have modded these to have standby switches. Is that really necessary?

Believerblues,makes no difference class A or not,when "burning in tubes",doing it for one night isnt going to hurt.Another thing to consider,if it concerns you,most guitar amps manufacturers that claim class A arent really a "true" class A.There is a lot of discrepency as to what constitutes class A among techs and amp builders these days and most amp builders claim class A even if all they do is cathode bias their amp,not 100% sure on the Jet,I have to look at a schem,but most amps arent true class A.Most amps you see that claim to be class A is just a marketing ploy by the maker.Mesa is one example I can give you off the top of my head,every model that has a "class A" switch is not even close.One that I can tell you is class A off the top of my head is the Champ.But even in a Champ,if you put a tube in there that happens to have a colder bias point,its no longer "true" class A.Dont want to get into the whole what constitutes class A argument here,but most arent actually class A.

I think one should say single ended?

But Push-pull (A/B) amps won't feel much pain being idle. I'm sure the single ended shouldn't have the high voltage on when idle.

I don't know if four tubes are used, the rules change and standby is advised. No clue yet.

Some scavenged internet gossips (could be true or false):

What is "Standby" for?

It was originally a way to cut down some of the wear and tear on the tubes that would otherwise be wearing out while they stood idle. Frequently you'll want to leave an amplifier on but not making any noise, like during a break between sets. The standby switch ensured that the amp would be quiet, and at the same time that the main power supply was disengaged from at least the power output section of the amplifier. This makes tubes last longer.

From the Mesa Boogie Express manual:

STANDBY: Perfect for set breaks...this toggle switch also serves an even more important purpose. In the STANDBY position (switchup), the tubes are at idle so that during power up they may warm up before being put to use.

Before the power is switched on, make sure the STANDBY switch is in the STANDBY position. Wait at least 30 seconds and then flip the STANDBY switch to its ON position. Following this simple warm up procedure helps in preventing tube problems and increase their toneful life substantially.

From the Genz Benz Black Pearl Manual:

STANDBY SWITCH: The Standby switch removes the high voltage power supply from the plate circuit of the output tubes to protect the tubes from “cathode stripping” when first powering up the amplifier. The recommended start-up procedure is to place the standby switch to the standby position, turn on the power switch and allow the amplifier to warm up for at least 30 seconds before switching the standby switch to the operate position. This will help to prolong the life of your output tubes.

Torres:

What's a "standby switch?" Fenders, Marshalls, Traynors, Boogie's all have one. Its purpose is to put the amp on idle while you take a break. The tubes have a filament that has to be heated up in order for the tube to work. Heating the filament is why the amp has to "warm up."

The standby switch leaves the filament heated up, and turns off the power and preamp stages. You can flip the standby switch off after a break and play right away. This extends tube life, as the filament doesn't have to be reheated every 45 minutes.

For a short break in the bar or club, put it on standby. But, if you and the other guys in the band are going away - turn all the amps completely off. A tube can go bad at any time. If the amp is on standby when the tube shorts out, you may have some damage. Only use the Standby switch when you are still around the amp.

When you first turn the amp on, turn on the on-off switch, but leave it on standby for about 2 minutes. This allows the filaments to heat up and be working right before you start playing.

I have developed a habit of always turning my Master all the way to 0 before turning my Pignose on or off.

Seems like the issue is weighing the wear and tear of turning the tubes on and off against the wear and tear of idling. Both wear on tubes, but which one more? In other words, if I play for 45 minutes and then work for 2 hours and then play 45 min., should I shut down or idle (no stand by, just turning the volume all the way down)?

Strum, I'd be interested in what David says about his V47s.

I wouldnt leave the amp in standby for 2 hours on a regular basis.The main purpose of a standby is to let the heaters warm up before the plates see high voltage.If your amp has certain rectifier tubes,such as a 5V4 there is a delay in the rectifier that keeps the high voltage from passing for a few moments so the rest of the tubes heaters get a chance to warm up before the rectifier delivers the high voltage.No need for a standby switch in these amps.Using the standby in between sets as has been described here was not actually the original intent,it is merely a convenient "side effect" of the feature.

Very informative thread. I have another question. Should I switch the amp to "Stand By" before turning the amp off or the other way around?