The present invention is directed to an apparatus for reproducing the bass components of an audio signal with a high degree of accuracy and minimal distortion, utilizing an enclosure of relatively small size. The apparatus comprises a substantially sealed enclosure in combination with a radiating diaphragm driven by an electromagnetic transducer, the principal diaphragm restoring forces being the elastic forces exerted against the diaphragm surfaces by the gaseous medium engaging such surfaces. The device is characterized by the elimination of the roll or surround joining the cone to the frame as heretofore always employed in reproducers of the air suspension type as the means for effecting a sealing of the enclosure, and the utilization of a rigid peripheral portion of the diaphragm immediately adjacent a parallel interior surface portion of the transducer mechanism to define a gap of minimal dimension, said gap being elongated in the direction of movement of the diaphragm, the clearance provided by said gap being maintained at minimal value consonant with movements of the diaphragm free from mechanical interference.

A speaker includes a T-shape iron, a ring magnet, a pole plate, a frame, a diaphragm, a coil core portion, a voice coil, a first annular corrugated plate, and at least one second annular corrugated plate. The second annular corrugated plate has is bonded to an inner side or an outer side of an outer section of the first annular corrugated plate and spaced from the coil core portion, thereby increasing a thickness and strength of an outer section of the first annular corrugated plate for bearing higher power such that the speaker generates clear sound and that an inner section of the first annular corrugated plate generates sufficient sound pressure when a power outputted by the speaker is low.

In a loudspeaker, the upper part and the lower part of a cone-shaped diaphragm with a voice coil are suspended from a frame by a ring shape suspension member, herein referred to as a first suspension means, and by a ring shape suspension member, herein referred to as a suspension means, respectively. At least one of the suspension means is formed of a mixture of elastic material such as rubber, with carbon fibers therein. The fibers are needle-like and are aligned radially in the material of at least one of the suspension means.

Herein disclosed are an improved vibration diaphragm and an improved cone edge of a loudspeaker, wherein the vibration diaphragm is formed of a foamed plastics which is formed with portions having a density or densities lower than the remaining portion of the diaphragm and/or which has at least one coating of resin applied to at least one surface of the foamed plastics in the form of an aqueous emulsion and wherein the cone edge is formed of a foamed plastics having a closed-cellular structure. The vibration diaphragm and cone edge, which may preferably be used in combination with each other, will contribute to improving the acoustic characteristics of the loudspeaker to a considerable extent.

In a speaker device, each inner peripheral edge portion of a conductive damper and an ordinary damper is fixed to an area in the vicinity of a lower end of a cylindrical portion of a connecting member, and each outer peripheral edge portion of them is fixed to a support member. The conductive and ordinary dampers are attached to an area within a constant winding width of a voice coil. When the speaker device is driven, the voice coil bobbin vibrates in an axial direction of the speaker device. The voice coil bobbin sometimes rolls due to various factors. Since a fulcrum of the rolling is within the winding width, a distance r2 from the fulcrum P11 to an intersection of a central axis of the speaker device and a plane surface including a center in the winding width becomes short, and the bobbin hardly rolls.