Filament supply question. Please help.

[Guitarman18]

Having spent some time around amps and recently around this forum, I was feeling as though I was gaining some sort of insight into how it all goes together. However, at the risk of completely embarassing myself and exposing my total lack of formal electronics training, can anyone answer this question for me please?

On the 6.3V tap of a PT that does not have a centre tap, I have always known that you can create an artificial centre tap by running a 100ohm resistor from each tap to ground. So far so good, however, as most of my experience is with Fender type amps, I most often see them over by the pilot light. Also in schematics the resistors are often represented right next to the transformer. ie. the first link in the chain.
Having spent some time looking at pictures of D*mbles and clones it seems that the resistors are placed off pin7 on the 3rd 6L6 and pin 2 on the 4th 6L6!! Almost half way along the chain.
Does this work because it's an AC circuit and I've spent too much time in DC. Can anyone enlighten me?

Many thanks for any help you can offer on this one.

Cheers.

[dartanion]

It doesn't really matter where in the filament chain that the virtual center tap resides. I done this where it is convenient in different amps with success.

[Guitarman18]

Thanks dartanion, it's reassuring to know that what I think I am seeing in the pictures is actually correct.

Cheers, Paul.

[galtjunk]

On my build it was most convenient to place them at the first power tube.