an Autoformer would work, because it’s one of the only speakers that presents a very benign 3-4 ohm impedance load.This statement ignores the fact that loop feedback compensates for this sort of thing.
Loop feedback compensates for the autoformer
How the designer set up the amplifier with the transformer plays a big role. The reason you do this BTW is to reduce distortion- all amps have higher distortion playing lower impedances, so if you can raise the overall impedance seen by the output devices distortion will be reduced. This is why Mac uses autoformers.
Autoformers reduce distortion
Since all forms of loop feedback are known to add higher ordered harmonic distortions as well as intermodulations.
Loop feedback causes distortion
Okay. Got it:
Autoformers reduce distortion but need to be compensated for with loop feedback which adds higher order harmonic distortion...the worse kind! 🤯
Sorry, couldn’t resist having a bit of fun with this! 🤪
I’m sure the interplay between these forces is well beyond the scope of this discussion and certainly well beyond my very limited knowledge.
Thanks all for your input! Much to think about.
Rob