The DRD as Jack Elliano shows it calls for 700V B+. It can be as low as about 550V and still have room to direct couple, so that is something to keep in mind.

To get 700V With a standard full wave rectfier will require about 1100VAC ! 550-0-550. This is doable especially if we use damper diodes but it means haveing a custom transformer made.

On the other hand, If we use a full wave bridge, solid state or hybred. We can get the necessary voltage with a standard 750V (375-0-375), 800V (400-0-400) and a choke input filter. I am kind of likeing this idea as these transformers are pretty thick on the ground, from the likes of Hammond, One Electron, Angela and just about everyone else. You might have a pair in stock, or can be recycled from an old project. (I know I do)

The next consideration is what we need for filaments. First off for this amp I am going to uas DC, or some sort of current reg for the 300b. The best I have been able to get with AC is about 5-6mv of noise. not too bad but I want better. This means at least one secondary at ~1.5A,6.3VAC , maybe more.

Two damper diodes, 6AX4 for example for the forward facing/positive voltage at the cathodes pair will do the trick nicely.

The direct coupled DH amp will put the filament winding at considerable voltage, use caution when selecting the TX for this job. Most do have adequate ratings.

To the PSUD simulator!
regards,
Douglas

Pardon the spelling and grammar, a long few days...John

hope you got some sleep