Maximum Power Transfer

[Electrostatic]

Quick question to all the electronic experts out there. Im not sure if this question has been asked several times and if it has i do apologize.


Can the theory of maximum power transfer be applied to audio electronics?

 

[audioguru]

If an audio amplifier uses maximum power transfer to a speaker then the speaker receives only half the power of the amplifier and the resistor or current regulation doing the transfer provides poor damping of the speaker's resonances. Power amplifiers are designed to provide maximum voltage transfer to a speaker which requires the amplifier's output to be an extremely low impedance which also provides excellent damping of resonances.
Nearly every stage of an amplifier has a maximum voltage transfer, except phonograph preamp inputs that provide a 47k load impedance to the magnetic pickup to damp its high frequency resonance only a certain amount. Some dynamic (magnetic) microphone preamp inputs have a certain load impedance to damp resonance.

 

[Nigel Goodwin]

As Audioguru has already suggested, it's VERY rare in audio - and is usually the last thing you want - an exception is valve audio amplifiers, where the impedance of the output transformer is matched to the impedance of the load. This is why valve amplifiers are large, expensive, heavy, and inefficient - they produce far more heat than the electrical energy they output, and are probably less than 40% efficient?.