Heater supply

[lowell]

I'm curious if a heater supply can be derived from the main supply line. Eg after the last preamp tube supply filter cap, can one add a voltage divider to get 6vDC to run heaters? I know current is an issue w/ heaters, but wonder if this can be done.

[ThermionicScott]

I'm curious if a heater supply can be derived from the main supply line. Eg after the last preamp tube supply filter cap, can one add a voltage divider to get 6vDC to run heaters? I know current is an issue w/ heaters, but wonder if this can be done.

Well, considering that a 12AX7 requires 300mA of heater current, and a Twin Reverb HT secondary is rated for something like 450mA total... probably not. The current draw would cause a tremendous voltage drop for the whole B+ chain, as well.

- Scott

[lowell]

right... How do you know the current rating for a PT secondary?

[ThermionicScott]

right... How do you know the current rating for a PT secondary?

Well, I posted what I thought I knew from memory... Uncle Spot's table indicates that the originals were only rated at 310mA, but replacements seem to be beefier -- Weber's replacement part is rated at 400mA, Magnetic Component's at 450mA, Hammond's at 516mA.

- Scott

[lowell]

cool thanks!