Princeton RVB Filaments.. Virtual CT or Real CT???

[Govmnt_Lacky]

Thinking about the center tap for the filament wiring on a Princeton Reverb. Which option is best/better? Using the dual 100 ohm resistors on the Indicator lamp as a virtual tap -OR- using the PT's 6.3V winding CT?

Thoughts and reasons...

[Justin Thomas]

As far as which one "works better" for noise, I've heard the artificial one; sometimes the tap isn't really in the center. I tend to look at it as a failure thing - in case of a fault, would I rather risk toasting a tranny winding or some resistors?

That's just me. I'm poor so I like to do whatever I practically can to save my trannies.

Jusrin

[mozz]

Once you have it finally built, try both ways. Put a meter on the speaker, you will measure AC millivolts of hum, one way will be lower. Or install a hum balance pot of 250 ohms and tweak to lowest hum.

[pdf64]

I suggest to DC elevate the CT.
It will mitigate a potential hum source, make the amp less fussy about the valves used in V1 and V3 sockets.
See 'heater elevation' http://www.valvewizard.co.uk/heater.html
It only needs a couple of resistors (I typically use 220k and 47k) and a decoupling cap.