Floating paraphase question

[catalin gramada]

Hello, Does it help in balance a floating paraphase to replace the shared cathode resistor with a ccs like common mode in diferential to force into balance, please ? Thanks.0

[Helmholtz]

Which paraphase circuit?

I don't think a CCS can do much to improve balance (but might be wrong).
Other than with a differential stage you don't want to have the triodes to have equal gain.
Best paraphase balance is achieved when the gain of the second triode is exactly one.
This condition is already provided by the local NFB.
Acc. to Merlin large signal imbalance is caused by the different output impedances of the triodes.
He recommends to add a suitable build-out resistor to the second output:
file:///C:/Users/User/Downloads/floating%20paraphase%20inverter.pdf