Vibro Champ Heater Wiring

[trem]

I recently re-capped, and added a 3 wire power cord to a Fender VC. I wired it according to the schematic, and it all works/sounds fine. But I am confused. I am use to running a wire to Pin 2 and 7 of the power tubes, and a wire to Pins 4-5, and 9 of the pre tubes. What is the reasoning behind the VC scheme?
On the power tube the heater goes to Pin 2 and Pin 7 goes to ground. The pre tubes get a wire at Pins 4-5, and Pin 9 goes to ground. Can one of you guys explain this difference to me?
Thank You

http://www.ampwares.com/schematics/c...ibro_aa764.pdf

[stokes]

What you have in the schem is an older,outdated way of wiring the heaters.What we use now is a "twisted pairs" wiring of the heaters.It is a much quieter wiring scheme,you get your ground reference from either a CT on the winding from the PT or an artificial CT using two 100 ohm resistors to ground.

[trem]

OK -
So should I just go ahead and use both heater leads from the PT, go to Pin 2 & 7, then in phase to Pin 4-5 and 9? I guess this would be with the standard twisted wire, and should I then make a CT with 2 x 100 ohm resistors from each side of the pilot light/ground also?

[Tom Phillips]

OK -
So should I just go ahead and use both heater leads from the PT, go to Pin 2 & 7, then in phase to Pin 4-5 and 9?

Yes but you don't need to worry about "phase" in this situation.

I guess this would be with the standard twisted wire, and should I then make a CT with 2 x 100 ohm resistors from each side of the pilot light/ground also?

You can use either stranded or solid wire. And, yes, add the virtual center tap. An upgrade would be to attach the common point of the two 100 Ohm resistors to the cathode of the power tube rather than ground thus elevating the heaters.

Regards,
Tom