My mesa is my first tube amp and i never knew you had to change the tubes after a while. How often and why would you have to change the tubes in the amp?
when tubes are old and need to be changed, you're amplifier may start sounding worse than usually. In example, not so tight, it looses great part of bass response... how often you should change tubes? it depends on how much you play (and how your amp working), even if it is a quite variable thing. I would say tubes can last about a years or two if you are not a pro and not play every day. Even much more if you never use your amp at high power.
