How hot is too hot?

Check the current flow or look up the spec's for you amp. Current time the voltage will give you the power in watts.You can judge the heat by placing you hand near a 100w light bulb or as many light bulbs needed for the test.

I've noticed that too, working with 1950's and 1060's gear. I've assumed it is due to the fact that line voltages are higher now than they were then, in many areas 120-125VAC now instead of 110-117 then.

Can't offer any guidance re "how hot is too hot," other than the fact that I haven't encountered any transformer failures so far in a moderate amount of experience with equipment from that period.

Regards,
-- Al

When I rebuilt my MC240, the power transformer temperature went up a good bit. When I put my hand on it before, it was very warm but I could leave it on there all day. Now, it gets too hot to leave my hand on it for more than 30 seconds. but my bias was way off before the rebuild.

Humans are much weaker than wires/insulation and cores, so I don't think there would be any read degradation unless temperatures approached the curie temperature of the core (often >100C). I am sure your amps are no hotter than that!

Arthur