5V tap enough to power DC heaters and relays?

[Hardtailed]

but I figured out a circuit with three capacitors and a bunch of diodes that produces about 12V DC. I've posted it somewhere on the forum before.

I'm assuming you mean the image I attached in a message above?

By the way, the high gain channel will be a SLO level channel (basically a JCM800 with an extra stage), except the loop driver tube is after the channel volume so it won't get slammed as much. Which makes it similar to a Dual Rectifier really (except, it won't sound as mushy )

I see that the Dual Rectifier does rectify the heater supply, but only for V1
They're using just a bridge, a cap, and a pair or 150ohm resistors that I'm not sure what they do

[loudthud]

First, be aware that heaters draw a surge current when they are cold that could be more than 2X the expected current draw. Make sure the rectifiers can handle it.

Use Duncan's PSU designer to find the RMS current that the transformer and rectifiers need to pass. You might want to consider a small (1 pound) choke in a Pi filter. Hammond sells some like the 155B (6mH, 0.3 ohms) that can really reduce the ripple voltage when used with a pair of 4700uF caps.

[jaysg]

You can fine tune the secondary supply by using Schottky diodes instead of regular ones.