Patent ID: 6584204
Filing Date: 2003-06-24
Classification: H03G,H04R

Abstract:
A sound producing system, comprising:a loudspeaker to generate an audible signal; a transducer to generate a pressure feedback signal from said audible signal; and a controller to produce a controlled signal for application to said loudspeaker, said controller deriving said controlled signal from said pressure feedback signal and an audio input signal, said controlled signal improving the Sound Pressure Level (SPL) frequency response of said loudspeaker and reducing distortion of said audible signal by said loudspeaker within a predefined sub-bass frequency range, said controller comprising: a summing junction circuit to generate a filter input signal from said pressure feedback signal and said audio input signal; and a plurality of filters to generate said controlled signal from said filter input signal, wherein said filters reduce distortion in a predefined sub-bass frequency range, the reduced distortion comprising distortion associated with a non-uniform magnetic field of a component of the loudspeaker, a dependence of self-inductance of said loudspeaker component on cone position, and nonlinear stiffness associated with a cone of the loudspeaker; wherein said controller is configured so that said system has an associated closed loop sensitivity function S whose value is less than 1.0 in at least a substantial portion of the sub-bass frequency range.