Tubes and their problems

Daveyf,

I wouldn't presume to offer a tech answer when the likes of Ralph (Atmasphere) provides such comprehensive advice. That said, being a fellow "tube-o-phile," I would only mention that many manufacturers suggest that tubes be replaced within a certain life span. I surmise that tubes are more susceptible to failure or performance degradation if use exceeds recommended replacement points (as measured in hours in service).

In my case, ARC recommends that 6H30 signal tubes be replaced at the 4000 hour point. I understand that the new KT-150 power tube has a 3000+ hours life span.

I'm sure every manufacturer has its own recommended re-tube specs. Ralph, what do you recommend for your amps??

@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