In a previous article (Linear Audio Volume 0), Pierre investigated audio transformers as magnetic devices to determine and optimize leakage inductances. In the present one, Mr. Touzelet focusses on audio transformers as electrostatic devices to determine stray capacitances and their arrangement between terminals. Both viewpoints: the magnetic and the electrostatic are necessary and of the same importance, as they contribute to form a low pass filter, responsible of the high frequency response of audio transformers. Some general formulas are derived first, and then a method for estimating winding to winding and single winding stray capacitances is given, showing their arrangement between terminals, depending on the way windings are wound and terminals linked. Finally, he shows how these different stray capacitances combine into the capacitances across the terminals of an audio transformer.
On stray capacitances in audio transformers