Abstract: A very small audio speaker is described which has a broad-band electrical-mechanical transducer, a broad-band mechanical-air-transducer, and a special suspension system which combine to produce a substantially flat frequency response over substantially the entire audio range from about 50 Hz to about 18,000 Hz.The broad-band electrical-mechanical transducer has either a voice coil with two axially spaced subsections, or a magnetic field with two axially spaced subsections, with the other being continuous between two effective boundaries. Each subsection of the coil, for example, is generally centered on the boundary of the magnetic flux field so that as one subsection moves into the flux field, the other subsection moves out of the flux field at the same rate, thus maintaining a linear force as the coil reciprocates through a much longer distance than is possible using conventional continuous coil and magnetic structures.

Abstract: The present invention comprises a radially pulsating cylindrical surface operating as a wave transmission-line. The device is responsive to electrical means and may be practically utilized to generate pressure waves. A conventional electromagnetic driving system is employed with the novel cylindrical surface. A cylindrical voice coil is affixed to the cylindrical surface co-axially. The surface may comprise a matrix of helically oriented fibers suspended in an elastomeric impregnant. Damping means may be provided both internally and terminally. The radiation produced is omnidirectional.