• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Tube rectifiers


2008-08-20 9:42 pm
I'm building a preamp, and looking at rectifier options. Before I ask anything, this will use a dedicated VPL12-4000 filament transformer that I can tie to the HV B+ for safer heater to cathode potential.

I need a full wave bridge. I was looking at the 6BY5 with a pair of SS diodes for a hybrid bridge. I'd love to use two 6BY5s, but I would have to leave the filaments ungrounded to do so. Or, I suppose I could leave the filaments untied from the B+ and elevate them for both tubes?

The other option I'm looking at is the 6 or 12AX4. I love the aesthetic concept of seeing the four diodes lit up for a bridge, but I am curious if there are any drawbacks to using full wave bridges with tubes minus the lifespan.

Any weight in either direction if you had to select one?

Using 2 6BY5s requires 2 separate filament trafos.

You have the (IMO) right idea in going for a hybrid bridge. There's no double forward drop penalty and 1 filament trafo is "all she wrote". :D

You said preamp. Therefore, the B+ rail voltage can't be very "tall". While the vacuum diodes are darned good at suppressing SS diode switching noise, not generating the noise must be better. 2X Cree C3D02060F 2 A./600 PIV Schottky diodes will finish the bridge very nicely.