Is leaving an amp on for a long time bad?

[Garrett151]

I'm playing a series of gigs at a local jazz club and I'm concerned about leaving my amp on.
Basically, the head of my amp sits under a grand piano and runs straight out to the board.
I get to the club around 2, turn the amp on around 3 and soundcheck for a couple hours (really poor sound equipment). By then, the opener, who sometimes uses my amp, soundchecks and goes on at 8. We start at 9 and play till 11. Basically, I don't turn the amp off for 9 hours. Is this damaging the amp? It's a Mesa Mpulse 600 so it has a couple preamp tubes.

[Pilgrim]

Solid state gear lasts longest when it's never turned off. Turning it on and off constantly causes power surges...doesn't hurt a thing to leave it on all night - or all week - or all month.

Tubes have a service life, so it's best not to leave them on for days, but they work best after they're thoroughly warmed up and stable, so leaving them on for many hours at a time is also fine.

[paradigm_shift]

It is connected to a speaker right?

[Garrett151]

Originally Posted by paradigm_shift

It is connected to a speaker right?

Yeah I left that out. It's hooked up to two peavy 8ohm twelve inch monitors. I assume this is safe...? They're not from the board, just plugged into the amp.

[B-string]

Long time is weeks at a time with no signal applied. What you are doing is fine and the concern with cathode poisoning from no signal (still an open debate) is with output tubes not preamp tubes. You have no output tubes to be worried about in any case.

[B-string]

Originally Posted by paradigm_shift

It is connected to a speaker right?

Solid State output, no worries.

[boynamedsuse]

Originally Posted by Pilgrim

Solid state gear lasts longest when it's never turned off. Turning it on and off constantly causes power surges...doesn't hurt a thing to leave it on all night - or all week - or all month.

Tubes have a service life, so it's best not to leave them on for days, but they work best after they're thoroughly warmed up and stable, so leaving them on for many hours at a time is also fine.

As a clarification, tubes also undergo stress when they heat and cool, so power cycling a few times could decrease their life more than leaving them on for the whole day. (I suspect this varies depending on the power supply quality, temperature, circuit design, and other things but that is a valid generalization.) I think that is what you were saying, but I felt compelled to add my two cents.

[seanm]

Like others have said, 9 hours is nothing. Don't worry about it and enjoy the gig!

[Sneakypete]

My dayjob is in industrial electronics where many things are rated MTBF (mean time between failures) and for passive components and solid state stuff these are usually really big numbers often many hundreds of thousands of operational hours. These figures assume continuous use though - it's certainly true that inrush current causes extra stress to a circuit. One thing to be sure of though is that if the amp has a cooling fan you must make sure it's working properly and also that the inside of the amp is clean. A thick coating of cat hair is never a good idea!