Replace tube for your amps

[kldguitar]

The life of Tube is depended largely on use. High volumes, frequently moving gear, and overly high voltage at the wall are all factors in how long a tube set lasts.
It's never the whole set that goes, usually just one, but that's the indication it's time. With the exception of accidentally breaking a tube while moving the amp.
Tube amp tones are heavily colored by the type of tubes in them. You can find tubes that brighten a dark amp, darken a bright amp, lower or raise gain, change power output, so on and on.

http://www.kldguitar.com/tech%20article ... ech4).html