KT 77's in a HT 50?
- thephantum
- Posts: 1160
- Joined: Wed Jan 29, 2014 7:42 pm
- Location: Virginia, United States
There is no set number. KT77's have the same plate dissaption rate as an EL34 (25 watts), so the bias process is exactly the same:
Maximum Plate Dissapation is not 25 watts (if you do that it will burn the tubes up). It's the maximum desired plate dissapation and it should be some percentage of that number. I personally start at 70% (17.5 watts for EL34/KT77) and then dial in by ear from there.
Theoretically, it should live somewhere between 35mA and 40mA per tube, but that's a guess. I know I wouldn't want to hang the health of my tube amp on a guess.
- - Measure the plate voltage
- Do the math
- Measure and adjust bias current
- Rinse and repeat until dialed in
Maximum Plate Dissapation is not 25 watts (if you do that it will burn the tubes up). It's the maximum desired plate dissapation and it should be some percentage of that number. I personally start at 70% (17.5 watts for EL34/KT77) and then dial in by ear from there.
Theoretically, it should live somewhere between 35mA and 40mA per tube, but that's a guess. I know I wouldn't want to hang the health of my tube amp on a guess.
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