A loudspeaker apparatus includes a frame having an opening portion, a magnetic circuit constructed within the opening portion, a voice coil 27 in which a rear opening end portion is inserted into a magnetic gap of the magnetic circuit, a dome type diaphragm covered over the front opening end portion of the voice coil, and an edge for holding an outer peripheral portion of the voice coil freely vibratingly, with the outer peripheral edge attached on an opening portion of the frame. A reinforcing portion formed at an outer peripheral edge of the dome type diaphragm is formed of a flat portion and a cone portion, and has a shape of being folded back in a sound radiating direction toward a front.

A speaker structure having a supporting base with a magnetic circuit in a lower portion, a sound cylinder with a tube with wires on one end, which one end is placed in the magnetic circuit and the other end is higher than the supporting base. A vibration diaphragm having a round concave shape covers the top of the sound cylinder. A flexible free end fixture with a wave transmission in the middle section has one end connected to the supporting base and the other end directly connected to the tube of the sound cylinder. Thus favorable movement flexibility is achieved by the adhesion of the free end fixture at the lateral side of the sound cylinder. The space above the sound cylinder is vacant to independently install a vibration diaphragm with an enlarged area to effectively enhance the output of sound pressure.

A speaker device includes a speaker diaphragm composed of a selected acoustic diaphragm material whose acoustic loss coefficient (tan .delta.) is more than 0.02 in a frequency band over 20 kHz, and including a dome positioned at the center of the diaphragm and shaped to be substantially arcuate in its cross section, with an edge positioned outside the dome and formed integrally therewith through a link; and a conductive one-turn ring inserted into a magnetic gap and bonded fixedly, at one end thereof, to the link between the dome and the edge of the speaker diaphragm. In this device, signals of a frequency band over 20 kHz are reproduced by utilizing the split vibrations of the speaker diaphragm.

An electro-acoustical transducer has a voice coil assembly, a diaphragm coupled to the voice coil, a permanent magnet arrangement for providing a magnetic field in an air gap, and support means for axially centering the voice coil assembly in the air gap and means for maintaining axial alignment of the voice coil assembly during movement thereof. In one embodiment, the permanent magnet arrangement comprises two concentrically disposed permanent magnets whose adjacent faces are oppositely poled. In some embodiments, the support means comprises a rigid diaphragm disposed between rigid top and bottom spiders and at least one slideably mounted rod connecting the two spiders. Other embodiments of the invention use a single rigid spider which is guided on a single stationary centering rod.

An edge-driven diaphragm loudspeaker driver is configured such that the suspension system of the driver is connected to the voice coil rather than to the diaphragm. Thus, the diaphragm in the loudspeaker is free of suspension systems connected to or extending from the diaphragm. By attaching the surround suspension to the voice coil rather than to the diaphragm, the diaphragm is isolated from the influence of spurious high frequency vibrations in the suspension system, thereby increasing the performance of the loudspeaker at high frequencies. The loudspeaker driver configuration also provides for a longer excursion range for the voice coil/diaphragm assembly, which allows for the driver components to be more accurately aligned during manufacturing, thereby enabling the loudspeaker driver to operate as a full range unit by producing low output frequencies.