This could be a troll post but here goes the 5 cent explanation:-
Electronics has always been sensitive to temp. changes & it is well-know fact that variations in temp. has a moderate/drastic effect on the perf. The moderate/drastic effect comes from how the designer implemented the circuit i.e. did he take temp. effects into account or not. As the current flows thru the electronics, the devices heat up but the ambient air around them is still cold in comparison & so during this time the perf. varies. It takes a while for the enclosed air inside the chassis to equalize in temp. Once the temp. stabilizes then there is no more heating to take place & the electronics is surrounded by an isothermal which allows the various bias operating points of the devices to stabilize. Now the devices begin operating where the designer intended them to. In ss gear this takes 20-30 minutes at a min & in tube gear it takes about 1 hr.
I'm afraid it's just the nature of the beast!
Electronics has always been sensitive to temp. changes & it is well-know fact that variations in temp. has a moderate/drastic effect on the perf. The moderate/drastic effect comes from how the designer implemented the circuit i.e. did he take temp. effects into account or not. As the current flows thru the electronics, the devices heat up but the ambient air around them is still cold in comparison & so during this time the perf. varies. It takes a while for the enclosed air inside the chassis to equalize in temp. Once the temp. stabilizes then there is no more heating to take place & the electronics is surrounded by an isothermal which allows the various bias operating points of the devices to stabilize. Now the devices begin operating where the designer intended them to. In ss gear this takes 20-30 minutes at a min & in tube gear it takes about 1 hr.
I'm afraid it's just the nature of the beast!