Tubes and their problems

+1 Mapman.
Tubes are great when they work well, and a real PITA when they don't.
Luckily, they seem to work well most of the time.

@Bifwynn, we don't have a recommended set of hours on the tubes we use. FWIW power triodes are often good for about 10,000 hours owing to their simplicity. Octal base signal triodes can often do that as well.

We've been warranting our tubes for a year for some 3 decades now and getting away with it, so they must last a good long while.

Solid states usually don't have tube problems. The blown transistors happen far more rare than tubes and not too difficult to replace.

@Ralph -- any idea why ARC recommends that its power tubes be replaced every 2000 hours (6550s and KT-120s); 3000+ hours in case of KT-150s. I'm sure you know that KT-150s ain't cheap. My amp uses 8 KT-150s. Yikes!!

Not sure this is relevant, or that I am framing the point properly, but KT-150s are rated to have 70 watts of plate dissipation capability; ARC drives them to about 27 watts.

Does that permit the inference that ARC is not driving their power tubes all that hard and that tube life expectancy should be longer?

Sorry for not framing my question in a technically correct way. But I assume you know what I mean.

Could you put a little more gloss on why your power amp tubes last so long??

BIF

Power pentodes just don't seem to last as long as triodes, in a nutshell.