Hello I am new to this forum and stumbled upon it because it was one of the few forums I could find for this type of question. I have been trying to research Mag Amps for audio applications over the past week and have been unable to find much detailed information on them. The most helpful site I was able to find was http://www.butlerwinding.com/elelectronic-transformer/mag-amp.html. I still don't completely understand their implementation (the control winding for example in the schematic on the link I referred to above). I was hoping some people on this forum might be able to point me to some places that have alot of resources on audio mag amp design and theory. I appreciate any help that you guys can offer. Thanks, Keith.

 

Here are some quotes from Integrated Publishing:

However, the magnetic amplifier has a few disadvantages. For example, it cannot handle low-level signals; it is not useful at high frequencies; it has a time delay associated with the magnetic effects; and the output waveform is not an exact reproduction of the input waveform (poor fidelity).

As stated earlier, the magnetic amplifier does not amplify magnetism, but uses electromagnetism to amplify a signal. It is a power amplifier with a very limited frequency response. Technically, it falls into the classification of an audio amplifier; but, since the frequency response is normally limited to 100 hertz and below, the magnetic amplifier is more correctly called a low-frequency amplifier.

They are called amplifiers because they can control large currents with small ones. I have never heard of them being used to amplify audio.