Patent ID: 8031882

Claim:
A sound reproduction system comprising an amplifier system, a speaker, first and second negative feedback means, and a third feedback means; the speaker having a diaphragm, a first voice coil mechanically coupled with the diaphragm, and motional measurement means having an output; the amplifier system comprising an amplifier with an input and an output, the amplifier output electrically coupled to the first voice coil; the first feedback means comprising first circuitry coupling the motional measurement means output with the amplifier input; and the second feedback means comprising a current measurement means electrically coupled with the first voice coil and having an output, the output coupled with the amplifier input; the third feedback means comprising a multiplier with first and second inputs and having an output; the third feedback means further comprising a motional signal correction means extracting a motional signal from the motional measurement means, and feeding a signal indicative thereof to the first input of the multiplier; the third feedback means further comprising a motional current filter means filtering out high-frequency signals from the current measurement means, and feeding a signal indicative thereof to the second input of the multiplier; the third feedback means further comprising equalization circuitry receiving the output of the multiplier and feeding a feedback signal to the amplifier.