6.3 to 12.6 schematic

[Guitarist]

Please check this over as I am bit unsure as to how the circuit is connected.

Does the bottom AC in go directly to the capacitors because it usually goes into a diode. Also aught pin 9 to be unconnected?

edit: added a 2'nd Voltage Doubler illustration.

[Old Tele man]

...it's a voltage-doubler circuit, the voltage from one diode "adds" to the voltage from the other diode across the other capacitor.

[loudthud]

For lowest noise you should ground pin 9 but DO NOT ground the center tap of the 6.3V winding or use the artificial center tap.

Dynaco used that circuit on some of their tube (HiFi) preamps. They used 1000uF caps and the voltage saged down very close to 12V with two 12AX7's. 25uF is too small and 25000uF is too big. What size caps are you going to use and how many tubes are you going to run?