V4 Hum Balance

[AEB-1]

I sacrificed a board, cut the filament traces, and installed a rectifier with capacitor. It made the problem worse due to fact that I couldn't get pure filtered DC. Even with 11000uf cap the dc had a hard notch which got bigger or smaller depending on the hum balance setting. It ended up with a raspy buzz rather than a hum. It did stop the additional hum that you get when you touch the 6800 ohm resistors on the sensitivity switches.
Restoring the original filament traces gets it back to the original hum levels.

I'm going to continue the investigation with the original filament layout.