Current corrected AF amplifier

The majority of modern AF power amplifiers drive the loudspeaker(s) with a voltage that is simply a fixed factor greater than the input voltage. It is fairly evident, therefore, that the power delivered by such amplifiers is inversely pro- portional to the loudspeaker impedance, since the cone displacement of a loudspeaker is mainly a function of the current sent through the voice coil, whose impedance may vary considerably over the relevant frequency range. In multiway loudspeaker systems, this diffi- culty is overcome by appro- priate dimensioning of the crossover filter, but a different approach is called for when there is but one loudspeaker.