Question about independent bias

[Firestorm]

Thanks to everyone for their respnses.
Earlier in this thread, Bob-I said

Typically seperate bias adjustments are used to balance an output xformer with unequal DC resistance on the 2 sides of the windings. If the AC impedance matches you'll have some xover distortion if the idle is not matched.

Can someone please explain this, maybe by example? Or better yet, direct me to some suggested reading on bias supplies in general?

Thanks
Tom

Not quite an explanation of Bob-I's observation, but here is what KO'C says in TUT1 6-32 - 6-33:
"The transformer responds to signal currents. It also responds to DC idle currents. An imbalance in the DC currents in the primary halves can cause a flux bias in the transformer core. This means that a tiny magnetic field proportional to the imbalance will be present, which must be overcome by the signal, thus robbing some of the output power...The DC current is usually modulated by AC ripple. If the primary DC currents can be matched, then the AC ripple components will cancel and no hum will be present in the secondary."

[toml]

Firestorm:

Thanks for the information. At some point I need to pick up the TUT series of books.

Tom

[Structo]

Tech jargon aside, I like the implementation I did on my D'Lite 44.
Instead of getting a 3-5 ma difference on the power tubes I can now get them tits on.