Winding an output transformer for PL36 push pull

[Kalee20]

Capacitance should not be a problem at audio.

It is though - if you have enough turns for the lowest frequencies (enough turns to not saturate the core, or enough turns to have sufficient inductance, whichever figure kicks in first), then there's usually enough capacitance to start shunting the signal at the highest audio frequencies.

Careful winding, maybe with some interleaving between layers, can help here, although it hurts other aspects.

And, if you have negative feedback around your amplifier, then capacitance in the output transformer is bad news anyway as it can cause instability and oscillation. Never mind whether it is audible or ultrasonic - you just don't want it! Taming it usually involves putting a single dominant HF roll-off somewhere, and if the transformer capacitance/load resistance has a roll-off at not far above AF, then you may have to introduce something within the audible frequency range, to kill it.