There are a few amps that are manufactured with a digital clock built in so you can keep track of "on time" and have some approximate idea of when the tubes might need attention (some ARC amps for one). It is also interesting just to have some idea of the amount of time you spend listening.
You can add such a timer in several ways, the simplest of which is to plug one into a switched outlet on the preamp (if you have one). More challenging is to design a timer interface that runs off the 12v trigger. Or you can just start and stop a timer manually (of course it is easy to forget).
My timer shows about 10 hours per week on the average right now. At that rate a set of 6550 amp output tubes should last at least 2 years. However, it all depends on the amp, the tubes, the amount of use, the level of play and some luck etc.
You can add such a timer in several ways, the simplest of which is to plug one into a switched outlet on the preamp (if you have one). More challenging is to design a timer interface that runs off the 12v trigger. Or you can just start and stop a timer manually (of course it is easy to forget).
My timer shows about 10 hours per week on the average right now. At that rate a set of 6550 amp output tubes should last at least 2 years. However, it all depends on the amp, the tubes, the amount of use, the level of play and some luck etc.