What is audio output transformer?
An audio transformer is an electromagnetic device that is intended to isolate an input circuit from an output circuit and provide filtering to a signal that passes through it. It is an audio device because it is designed to operate on signals with a frequency spectrum in the audible band.
What does an output transformer do?
First off, let's examine what an output transformer is and why someone would inquire about replacing it. ... The transformer's function is to convert the high-voltage/low-current signal from the amplifier's power tubes into a low-voltage/high-current signal to power the speakers at a low impedance.