How HOT is too HOT?

[JoeCon]

Gentleman,

I'm just finishing up a Rockster KT66 beauty, well to me anyways. So I'm in there taking voltages and find across my 200 ohm bias resistor I have 28 volts. So 28/200 = .140ma /2 =.070ma per tube. 383V on plates - 28V = 355 x .140 = 49.7 / 2 = 24.85W per tube. Edcor PT 280-0-280 200ma driving them.

Too Hot? I've read they like to be run hot. They sound great and nothing turning red or melting down. These are the Shuguang KT66 tubes.

Thanks.

[martin manning]

KT66 max anode plus screen dissipation is 28.5, 24.9/28.5=87%... looks fine for a cathode biased amp.