EL34 Bias Question- 69 Super Bass

finalapproach2

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Seeking guidance! Just bought a 69 Super Bass, installed new set of Mullards (EL34s/CV4004), did some checks: 484V Plate voltage, -40 bias voltage, 42 milliamp draw on pin 8 (Cathode I think) of all 4 power tubes. Amp sounds great, but those tubes seem very hot. Are these measurements over the often states 70% tube output? One fella alleged that whatever the current draw is on the cathode pin 8, is actually less at the plate. If so, this "appears" to be about a 69.5% tube output. If untrue, another calculation resulted in 82% tube output (yikes). It sure sounds nice though...
 
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yladrd61

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Most EL 34 screens draw approx 4 ma current at idle 25W / 484 VDC = 0.0516528926 x 0.736 = 0.038016529 + .004 = .042016529 so you are running around 73.6 % of max dissipation about 18.4 watts per tube.
I usually run them at around 65% which would be about 37 ma cathode current.
 
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Norfolk Martin

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42 ma total cathode current is a bit hot compared to how I usually set EL34s with that sort of plate voltage I go for 36-38.
 

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