Installing JJ KT66s in a Sunn Model T reissue head.  The bias needs to be dialed down to get 60mA per side, as these run hotter than the average 6L6GC.  30mA per tube at this amp’s plate voltage (489V) yields a nice 60% plate dissipation.  Definitely thicker when cranked, but doesn’t seem any less loud than 6L6GCs, even though it’s 25W dissipation per tube, instead of 30W.

Installing JJ KT66s in a Sunn Model T reissue head.  The bias needs to be dialed down to get 60mA per side, as these run hotter than the average 6L6GC.  30mA per tube at this amp’s plate voltage (489V) yields a nice 60% plate dissipation.  Definitely thicker when cranked, but doesn’t seem any less loud than 6L6GCs, even though it’s 25W dissipation per tube, instead of 30W.