Tubes Asylum

RE: Plate dissipation.

142.206.2.21

This Post Has Been Edited by the Author

In Reply to: RE: Plate dissipation. posted by Nunki on March 17, 2017 at 01:12:47

Hmm, not quite. Bias voltage is one thing, actual current is another. Forget the KT120 or KT150 for the moment, and suppose you're installing a new fresh set of tubes, same model and make. A given bias voltage will not produce (or restrict, rather) the current in an equal fashion between the two sets of tubes. One set might have a higher current output (closer to an open circuit). For the same reasons, this is why one would adjust the bias as tubes age. As the use builds up, they lose life in the form of current output (and I think transconductance as a result), so you have raise your bias voltage (bring up the negative value closer to zero), to restore the output level. Of course, there's a point where this cannot be done anymore (limitation of bias circuit), and a new set of tubes is necessary.
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May your tubes be lively, warm, and long-lasting. Holy be thy heater.

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