Best temperature for optimum tube performance

I can only add this... I have an Audio Research D160 tube amp from the early eighties, 1982 to be exact. It uses 6550 tubes biased to 65 mV, according to factory specs. Way to hot for any practical life. I have "detuned" them to 46-48 mV to calm things down while maintaining proper gain.  The amp came equipped with two fans to bathe the tubes in cool air.  And naturally, per the owner's manual, the amp takes a couple hours of use to achieve thermal equalibrium. Use this to your benefit. The detuning and the fans really help in this specific example.

Happy listening

Fall, Winter, Spring, CHANGE! That's me. I can't take the heat, and I can't take the noise from the fans or AC in the Summer.. I change amp types, plane and simple. Class D are just fine with a little tweak here and there for the 3-4 months of heat.. 

I look over the valve amps, make any changes I want to do.. Then they go back in service around Halloween. If we have a party here, after the party.. :-)

Sometimes I sneak out my MC240 or 225 in the summer, play the Beach Boys, on the deck. Pair of old Heresy's or something. It just works.  

Regards

Ever look at a "combo" guitar amp? For example, a Fender Twin Reverb (I’ve owned and abused a couple of these) has 4 6L6 power tubes and 6 preamp tubes, all mounted upside down venting heat into the amp (although they’re uncovered...still...), and if you tilt it back it’s worse heat wise...but my amps never failed to work tirelessly. Kinda makes hifi stuff look weirdly delicate and wimpy...vibration? The amp is also in the same space as 2 12" speakers and still manages to work...all night...

Something not going right for you?

Lol!

My three ARC amps (NOT TUBES) each have 32 output transistors and 3 cooling fans each.  So, 96 output transistors and nine cooling fans.  If I run them really hard for say an hour their temp never goes over 100 F.  Yes, I measure them with a BBQ probe remotely.

Although this does not speak to tubes directly, I would say that if the interior of your cabinet is close to the ambient temperature of the room
you are good to go.

A remote thermometer is very cheap and worth it if you are asking the question.  Start out cold and log the temps against time as well as noting room temp.

Let the snarking begin!

Regards,
barts