Bias voltage from 50v tap or PT secondary ?

[StrummersOfThunder]

Any benefit from using the 50v tap vs tapping off the secondary to the rectifier ?

6g3 schematic shows the bias voltage being supplied by the rectifer supply voltage. However the hammond 290BEX has a dedicated 50v tap.
The secondary voltage is 325.

Is the only difference in the bias circuit going to be the size of the dropping resistor in either case?

For waht its worth im installing a bias pot per the hoffman diagrams.

[MikeC]

I am wondering the same myself. I'm building a "Princeton Deluxe" which is an AA1164 Princeton Reverb including it's PI mated with an AB763 Deluxe Reverb power section to produce approx. 22W RMS. A Deluxe Reverb PT, OT & choke will be used. What are your thoughts Ant's?

[StrummersOfThunder]

I'm building a "Princeton Deluxe" - that's an AA1164 Princeton Reverb including it's PI with an AB763 Deluxe Reverb power section to produce approx. 22W RMS. A Deluxe Reverb PT, OT & choke will be used. I am wondering the same myself. What are your thoughts Ant's?

The only major difference I can think of would be winding impedance that the rectifier tap would include vs the smaller winding of the bias tap ?

But if the end result is just -ve DC surely either would be fine ?

[MikeC]

I'm building a "Princeton Deluxe" - that's an AA1164 Princeton Reverb including it's PI with an AB763 Deluxe Reverb power section to produce approx. 22W RMS. A Deluxe Reverb PT, OT & choke will be used. I am wondering the same myself. What are your thoughts Ant's?

The only major difference I can think of would be winding impedance that the rectifier tap would include vs the smaller winding of the bias tap ?

But if the end result is just -ve DC surely either would be fine ?

I'm thinking to use the 50V PT tap because 1/. It's much lower voltage than the HT tap and if "something was to fail" in the bias circuit there may be less damage and 2/. If said "something was to fail" and the connected PT winding was to go open then at least I would still have an HT tap I could use for the bias supply as a repair (no need of a new PT). Can't think of any other reasons!

[StrummersOfThunder]

I'm building a "Princeton Deluxe" - that's an AA1164 Princeton Reverb including it's PI with an AB763 Deluxe Reverb power section to produce approx. 22W RMS. A Deluxe Reverb PT, OT & choke will be used. I am wondering the same myself. What are your thoughts Ant's?

The only major difference I can think of would be winding impedance that the rectifier tap would include vs the smaller winding of the bias tap ?

But if the end result is just -ve DC surely either would be fine ?

I'm thinking to use the 50V PT tap because 1/. It's much lower voltage than the HT tap and if "something was to fail" in the bias circuit there may be less damage and 2/. If said "something was to fail" and the connected PT winding was to go open then at least I would still have an HT tap I could use for the bias supply as a repair (no need of a new PT). Can't think of any other reasons!

Good point
Presumably that approx 100k resistor would become much smaller with the 50k tap

[sizzlingbadger]

I would use the 50v tap, as Mike has said, less voltage (stress) and lower impedance would make it more stable / less noisy.

[StrummersOfThunder]

Id tap that

[MikeC]

The only major difference I can think of would be winding impedance that the rectifier tap would include vs the smaller winding of the bias tap ?

But if the end result is just -ve DC surely either would be fine ?

I'm thinking to use the 50V PT tap because 1/. It's much lower voltage than the HT tap and if "something was to fail" in the bias circuit there may be less damage and 2/. If said "something was to fail" and the connected PT winding was to go open then at least I would still have an HT tap I could use for the bias supply as a repair (no need of a new PT). Can't think of any other reasons!

Good point
Presumably that approx 100k resistor would become much smaller with the 50k tap

Use the Deluxe Reverb AB763 schematic

[StrummersOfThunder]

I'm thinking to use the 50V PT tap because 1/. It's much lower voltage than the HT tap and if "something was to fail" in the bias circuit there may be less damage and 2/. If said "something was to fail" and the connected PT winding was to go open then at least I would still have an HT tap I could use for the bias supply as a repair (no need of a new PT). Can't think of any other reasons!

Good point
Presumably that approx 100k resistor would become much smaller with the 50k tap

Use the Deluxe Reverb AB763 schematic

Yep yep