An application of linear motor to loudspeaker systems

The authors describe an application of linear motors to loudspeaker systems. The loudspeaker system being developed is based on a novel concept of woofer loudspeakers. It has the characteristics of linear drive, low distortion and nondirectional acoustic wave propagation. The basic electromagnetic parts of the new system are in the form of a low-inertia linear motor with a cylindrical configuration; the vibrating part is a piston which is made up of composite materials inlaid with a Nd-Fe-B permanent magnet acting as the moving secondary of the motor. The equivalent circuit of the whole system is developed based on the principle of electromechanical-acoustic analogy. A simulation model of the speaker system has been developed for analysis purposes. Some design criteria of the system are also discussed by the authors