Ok it's 3 am, i'm bored, and had an idea

Lets say i'm in a band, we play an hour long set monday through saturday.. so 6 hours a week...

I'm running a 100 watt tube head at max output, on top of 2 4x12 cab.. Like, both gain ans master volume on 10 with an overdrive pedal.

Would it extend tube life to set the head somewhere other than the top of the cabs? I mean, do the vibrations of the cabs rattle the tubes to the point of shortening tube life?

Just a thought.
Hmm, I'm really not sure on that, I don't think it'd make a difference really, because the vibrations wouldn't really hurt the valves.
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There's no set amount of time for a tube life. Generally, under regular heavy use, power tubes should be replaced every 12-18 months. Less use or use at lower volumes will extend their life to up to a couple of years or more. Preamp tubes will usually outlast power tubes several times over. I know people who've had the same preamp tubes in their old JCM 800s and old Fenders for 10+ years.

As for location of the head, I thkn vibratiosn are negligable. You won't see any (appreciable) increase in tube life by not stacking the head on top of the cabs.
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