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Making the bias full wave certainly won't hurt, and as you say costs little. Since there is VERY little current drawn from the bias supply, half wave rectification is usually sufficient and can be made clean easily. Not worth debate.
If that makes a 93v or whatever supply, fine. As long as you get the voltages you want and the current capability you need - in this case none - and the level of filtration you ned, then it doesn't much matter how you do it. Oh within limits, of course. It isn't like ther is a wrong way. SOme ways are more efficient in parts count. And some reduce costs. Cost is not likely a big deal here, but if you were Fender or Marshall, a few thousand amps and parts costs add up.
Tapping off the HV winding exposes your bias supply to whatever sag is present, moreso than from a bias tap. DOn't know in your case how much. With close to 100v on the supply, you would want to have higher voltage filter caps. I usually use 100v caps for bias supplies that are around 50v. So I might like 200v caps here, or 150 or something.
The high gain is in the peramp, so the bias should not get involved in any of that noise, the only noise the bias affects is hum - and that only in the power tube stage. The hum you'd hear with the phase inverter tube pulled - balanced power tube idle currents, matched tubes assumed.
From this supply, yes, the voltage divider for the actual bias circuit would be in parallel with the resistor, as you say. With the high value resistors you have, though, your bias divider would need to be high value too, since it will be in parallel. That parallel will drop the voltage at the 93v point.
Without me going back to the previous page, you have 470k before the diodes, and 150k to ground after, I think. If you want bias around 45-50v and the divider you make totals 150k as well, that drops the lower half of the whole circuit divider to 75k. So your 93v might drop to 55v right there. As long as you didn't want more than the 55v, you can deal with that. But you can't make this raw supply and assume you can tack a conventional bias divider onto it and the voltage you have now remain. Follow?
I lied, the currentthrough this thing is not zero, it is a milliamp or so. No problem for the transformer, of course, but it is part of determining the voltage drops.
The tubes themselves won't draw any current from the bias supply, but your ultimate divider will. Not much, but it affects the numbers. To test your concept, you need to dummy up the bias divider and add it to this circuit. Without doing that, your 93v won't be there.
If that makes a 93v or whatever supply, fine. As long as you get the voltages you want and the current capability you need - in this case none - and the level of filtration you ned, then it doesn't much matter how you do it. Oh within limits, of course. It isn't like ther is a wrong way. SOme ways are more efficient in parts count. And some reduce costs. Cost is not likely a big deal here, but if you were Fender or Marshall, a few thousand amps and parts costs add up.
Tapping off the HV winding exposes your bias supply to whatever sag is present, moreso than from a bias tap. DOn't know in your case how much. With close to 100v on the supply, you would want to have higher voltage filter caps. I usually use 100v caps for bias supplies that are around 50v. So I might like 200v caps here, or 150 or something.
The high gain is in the peramp, so the bias should not get involved in any of that noise, the only noise the bias affects is hum - and that only in the power tube stage. The hum you'd hear with the phase inverter tube pulled - balanced power tube idle currents, matched tubes assumed.
From this supply, yes, the voltage divider for the actual bias circuit would be in parallel with the resistor, as you say. With the high value resistors you have, though, your bias divider would need to be high value too, since it will be in parallel. That parallel will drop the voltage at the 93v point.
Without me going back to the previous page, you have 470k before the diodes, and 150k to ground after, I think. If you want bias around 45-50v and the divider you make totals 150k as well, that drops the lower half of the whole circuit divider to 75k. So your 93v might drop to 55v right there. As long as you didn't want more than the 55v, you can deal with that. But you can't make this raw supply and assume you can tack a conventional bias divider onto it and the voltage you have now remain. Follow?
I lied, the currentthrough this thing is not zero, it is a milliamp or so. No problem for the transformer, of course, but it is part of determining the voltage drops.
The tubes themselves won't draw any current from the bias supply, but your ultimate divider will. Not much, but it affects the numbers. To test your concept, you need to dummy up the bias divider and add it to this circuit. Without doing that, your 93v won't be there.
). Looking at implementing this type of scheme, I know to look at the final or 'tail' resistor to make gross adjustments to the bias range because it is ultimately in parallel with the 150k voltage divider resistor shown in the ASCII schematic I posted.
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