You might want to actually read the thread before posting.
Oh, yes, I read the paper very carefully, and I understand it completely. It's very clear that they want Rplate to match Zload. But the implicit assumption is that Zload is constant, or at least is treated as a constant for all audio frequencies. What I'm proposing is to change Rplate to Zplate, and make Zplate match Zload. In theory, then the system would be precisely matched at all frequencies simultaneously. At the same time, the DC operating point of the tubes is left unchanged. Can you run these ideas past some tube amp gurus, like tubeguy or someone else? There's some serious work to design Zplate, and before I do it I'd like to get an opinion you trust.That is a good point. The problem with that is the impedance at each frequency would have to work out to the result of the equation laid out in the cavalli paper. Unfortunately I don't completely understand it and I've been tied up lately and haven't had time to further analyze it.
My question is how does such a thing affect the operating point? I also wonder if a shifting operating point is the basis of the problem at all. Based on LT spice simulation the DC offset servo in my amplifier keeps the operating point stable with a changing load impedance, at least of a single value. Any alteration from 0v at the output will cause the servo to adjust the impedance of the valve accordingly maintaining 0v at the output.
Seeing as the bottom triodes operating remains stable then the top triode will always be at 75ma/75v respectively in order to maintain a 0v output.
There's also the fact that conventional knowledge of deciding plate resistor value is not determined by load, this way of thinking was determined by John Broskie and the author of the cavalli paper. So the true nature of the plate resistor and the load escapes me. These guys are highly respected so they must know what they are talking about.
Have you gotten around to taking a look at the cavalli paper yet?
OK, let me know how that goes. I'm pretty sure I'm on good theoretical ground here, but only experience can prove a theory.I suppose I can attempt to email John Broksie, he's always talking about how he reads his emails.
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