Okay, lets say I buy a tube amp. Yay! pizza for breakfast, new amp, everyone's happy.

Now, concerning the tubes. Obviously I have to re-tube every once in a while.

Why do I have to replace them?

What happens if I DONT replace them?

Let's say I play at a low to medium volume and pratice for 1-3 hours a day, and gig every weekend.

How long should my tubes last?

Could I use the same stock-brand? or get a different brand?

And finally how will I know WHEN to change them?
ONLY tube thread
Fender American Standard Telecaster
Martin DC-16RE Premium

Fender Snakeskin Champ 12
Don't replace, them and your tone will be ****e and could blow your amp
I've had a friend who's owned amps in excess of 10 years without having to re-tube them, you'll know when it's time because of a drop in volume or worse tone
ohai little sig.