Question about Franchesca design.

[kricke40]

Hello! When I look at the pictures of Franchesca, that I downloaded from the files dep, that there are 2 resistors going to ground from the same lugs as the heather connects to the first of the Powertubes. I can´t find this in the published schematic of Franchesca, is this a mod? addon? Whats the purpose? noise reduction?

Thanks for information on this.

[paulster]

Presumably Francesca's PT didn't have a centre-tapped heater winding, so the resistors are 2x 100ohm from each heater wire to ground to generate an artificial centre-tap.

On newer PTs you'll have a centre-tapped heater winding so it's easier just to tie this to ground.

[mlp-mx6]

Those look to be 100 ohm resistors to serve as a ground reference for the heater circuit. If the power transformer does not have a center tap on the heaters you use this to create an "artificial" center tap.

[kricke40]

Sterling service as always!
thanks guys...