Moving coil loudspeaker.

摘要

The bass response of a moving coil loudspeaker is extended bu superimposing on the acoustic signals supplied to the voice coil (6) a compensation signal derived from photo-electric sensing of the displacement of the voice coil from its rest position, utilising reflection of light from a diffusely reflecting surface of the voice coil former (2) which has varying characteristics in the direction of coil displacement. The compensation signals are applied as positive feedback signals to the voice coil to produce forces on the latter which correct for the non-linearity of the voice coil displacements due, for example, to compression effects of the loudspeaker diaphragm oscillation. Since the compensation signal is zero in the rest position of the coil the additional power dissipation introduced by the compensation signals is minimal.