is it best to leave tube amp on for half hour at times when not using it or turn off?

[videodrone]

whats better for the amp and tubes?

To leave it on standy-by when its not in use for like a half an hour at a time or to just turn it off and then back on when in use again?

 

[Tom Hicks]

Good question!
Standby is better and here's why.The filiments inside the tube take a jolt every time you go from a state of zero voltage (off) to full operating voltage (on).Standby powers the tube down from the operating level to just a trickle of juice.The advantages include "instant on" rather than waiting for the warmup period.Also the tube doesn't get slammed when the voltage hits it,so tubes will last a lot longer.
By the way,when you are completely done playing,turn the OFF switch but don't use Standby.This will allow the filter caps to drain their residual voltage which is a good safety factor.
I'm just a player,so this info courtesy of my amp tech.

 

[TexRoadkill]

It's usually recomended to give any tube gear about 15-30 minutes of warm up time before you record or gig. Tube gear sounds different when the tubes aren't nice and toasty.