Marshall Valvestate 8040 Quiet Boost Channel

[chilidawg]

I don't think the PCB tracks can withstand any more abuse from the two 68 ohm power resistors heating up. I have repaired the tracks that were previously burnt to crisp and increased the resistors wattage from 3W to 5W but it seems not enough, even the flux residue inside the solder holes liquify and boiling when the tube is on.

Opted to use a 12V regulated supply for the tube heaters.

[g1]

I think you will still need to dump the same amount of power as heat, so interested in hearing how you implement this and the result. I guess if the regulator is on a heatsink that should solve the issue.
Dropout voltage is usually 2V for standard 7812, so it will need a minimum of 14V input at all times.

[chilidawg]

I think you will still need to dump the same amount of power as heat, so interested in hearing how you implement this and the result. I guess if the regulator is on a heatsink that should solve the issue.
Dropout voltage is usually 2V for standard 7812, so it will need a minimum of 14V input at all times.

I ended up using this small DC to DC converter module because I didn't like the amount of heat that I felt when I touched the 7812 regulator despite I changed to a bigger heatsink. It was after all, dropping 10V at 150mA.

I didn't add any LC filtering to the module output since it's switching above 1MHz. The tube doesn't pick up any switching noise.

Amp is already back with the owner. He's happy and I'm happy