300B Warmup versus other tube or SS amps?


Anyone have experience in warming up their 300B SET amp?  My push pull tube amp comes on duty after about 15-20 minutes or so of warmup.  My 300B sounds distinctly better after 60-90 minutes of warmup.  If it's on for several hours it may even marginally improve from there.  It sounds a bit flat out of the gate (no warmup).  My other amps are not as sensitive to this.

I am just curious to what folks have observed in there setups.  
128x128jbhiller
I let my ANK interstage monos warm up for about 30-45 mins usually while preparing and enjoying dinner. There is some slight improvement after that but not much.
That is surprising.  The heater in most SETs should get the tubes to optimal temperature within about 10 minutes.  I wonder if the heater isn't working right.  
5-10 minutes max for all 300B SET amps I used (and that’s a really long list), idle is fine.

Solid state tend to take more time to be optimal in my prior ownership: 30 minutes minimum (low volume listening needed, idle isn't good enough). The classic Krell and Aragon Class A amps took longer (an hour of low volume listening).
@bsimpson, a bit off topic but can you share what 300b amps are your favorites? You intrigued me with your note that you’ve owned a few.