How to make my 5F2H a little Browner

[6267]

Resistor on CT of power transformer was sometimes used before diodes were commonly available (outside of adding a tube) to "back bias"...you can take a negative voltage to bias with between the tap and resistor (sort of cathode biasing the entire power supply). You could not use the negative voltage though, and make a switch that shorts the resistor out. You might need a surge limit cap in parallel though to protect the switch.

[MWJB]

"Is there much performance difference between the 5V4GA and the 5Y3?" Yes, the 5V4 is tighter sounding. A technical difference is that it also has a slow warm up, good for amps with no standby.

[6267]

Those silvertones are phillips ECC83/12ax7...made in holland is always phillips. Eventually most Euro production was via phillips. I have some *fine* EF86 from holland, sound as good or better than telefunkens. 5v4s are nice, I like the ST glass anyway. B+ goes up a lot compared to my radiotron 5y3, not so much compared to my late 60s GE 5y3.