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I've read about the Marshall power scaling, where as long as the screens and the neg bias track each other the hcaracter of the tube is supposed to stay the same (ok, close enough anyhow). SO Marshall has an autobiasing feature, kewl, digital from what I've read, great but...
Why can't we do that in reverse?
I want to adjust the fixed bias with a pot, and use a tap off the bias feed to adjust the voltage to just the screens. I'm not great with transistors, but it seems to me this is basically what they do, feed voltage into the gate and that meters the voltage/current across the other two pins.
Assuming it's not quite that simple, there must be regulators I can buy where the voltage on one pin adjusts how much voltage is let through in a linear fashion, so either it's a circuit I can build myself with a few parts, or a part I can to buy, either way seems like a no brainer.
My understanding is that baarring some kind of failure, the screens don't draw monumental amounts of current, so that should make things easier.
So if anyone knows, who's done something like this, or why won't it work? It seems simple enough.
Why can't we do that in reverse?
I want to adjust the fixed bias with a pot, and use a tap off the bias feed to adjust the voltage to just the screens. I'm not great with transistors, but it seems to me this is basically what they do, feed voltage into the gate and that meters the voltage/current across the other two pins.
Assuming it's not quite that simple, there must be regulators I can buy where the voltage on one pin adjusts how much voltage is let through in a linear fashion, so either it's a circuit I can build myself with a few parts, or a part I can to buy, either way seems like a no brainer.
My understanding is that baarring some kind of failure, the screens don't draw monumental amounts of current, so that should make things easier.
So if anyone knows, who's done something like this, or why won't it work? It seems simple enough.
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