Abstract: An electroacoustic transducer 20, such as a speaker, a headphone, an earphone, a microphone, an acoustic wave sensor, etc., includes magnet plates 21 and 22, the entirety of which are formed like a disk or a ring; and an acoustic diaphragm 23 disposed parallel to said magnet plates 21 and 22 and having a conductor formed on the plane thereof; wherein a component parallel to the vibration plane of said acoustic diaphragm 23 is zero or in the radius direction of said magnet plates 21 and 22 in the direction of magnetizing respective partial areas of said magnet plates 21 and 22, and angles formed by said magnetizing direction with respect to the vibration plane of said acoustic diaphragm 23 are made gradually different from each other in accordance with the distance from the center axis of said magnet plates 21 and 22.

Abstract: A weight is attached to the rear side of a magnetic circuit of a speaker unit. The tip of a boss that projects from the front side of the weight is joined to the rear side of a center pole of the magnetic circuit with a bolt. Even if reactive force that is generated when an electrical signal is converted into mechanical vibration by the magnetic circuit and a voice coil and sound waves are emitted from a vibration plate is transmitted to the magnetic circuit, the vibration of the magnetic circuit is suppressed by the weight. In this manner, sound quality with a good transient characteristic can be obtained.

Abstract: An acoustic device having a heat producing device, such as an amplifier and a heat sink for transferring heat from the amplifier. The acoustic device has a cone having an inner surface, and a support structure defining a volume. The heat producing element and the heat sink are positioned in the volume.

Abstract: An internal magnetic circuit is formed by a plate forming a pole piece, a vertically magnetized magnet attached to a bottom face of the plate, and a yoke attached to a bottom face of the magnet. A magnetic gap is formed between the plate and the yoke. The yoke includes a bottom part attached to the bottom face of the magnet, a side part standing on the side of the plate, and a folded-back part folding downwards over the side part to face the magnetic gap. Thus, the internal magnetic circuit having a uniform magnetic flux density inside the magnetic gap along the direction of its length is provided.

Abstract: In a loudspeaker, even if an interval between a diaphragm and a yoke is small, a lead wire, an end of the coil wire of a voice coil, moves upward and downward in and/or over a cutout portion formed in the yoke, and does not collide with the yoke. The loudspeaker does not have disadvantages, such as noises and disconnection of the end of the coil wire, and can be thin.

Abstract: A speaker 300 is formed using a plate such as a mobile phone display window 310 as a vibrating element. At least two dynamic actuators 950 are positioned behind the edges of the window 310 to actuate the window 310 through its boundary region so as to leave a large uniform area behind the vibrating element for containing any components, e.g. a display or battery.

Abstract: There is provided a speaker unit comprising: an elliptical vibrating diaphragm; a cylindrical voice coil secured at one end thereof on the center of the elliptical vibrating diaphragm; a frame structure for movably supporting the vibrating diaphragm, said frame structure being formed into a rectangular or elliptical shape and having a through hole in the center thereof; a magnetic circuit formed by (1) a top plate having a rectangular shape and having a through hole in the center thereof, (2) a plate-shaped magnet having a rectangular shape and having a through hole in the center thereof, (3) a back plate having a rectangular shape and having an upright pole on the center thereof. In this speaker unit, the top plate, the plate-shaped magnet and the back plate each has a width which is narrower than that of the frame structure in its shorter axis.

Abstract: A first magnet is provided in an upper case and a second magnet is provided in a lower case so that these magnets face each other. These magnets are magnetized in opposite directions. A diaphragm having a drive coil is placed between these magnets. Thus, magnetic flux emitted from the respective magnets bends in a direction approximately perpendicular to the initial direction of emission of the flux. In the magnetic field, the component of the magnetic flux in the direction of radiation proportional to the driving force is dominant, and is symmetrical relative to the direction of vibration. Therefore, the sound pressure of the reproduced sound is increased and the secondary harmonic distortion caused by asymmetry of the driving force can be reduced.

Abstract: A weight is attached to the rear side of a magnetic circuit of a speaker unit. The tip of a boss that projects to the front side from the weight is joined to the rear side of a center pole of the magnetic circuit with a bolt. Even if reactive force that is generated when an electrical signal is converted into mechanical vibration by the magnetic circuit and a voice coil and sound waves are emitted from a vibration plate is transmitted to the magnetic circuit, the vibration of the magnetic circuit is suppressed by the weight. In this manner, sound quality with a good transient characteristic can be obtained.

Abstract: To realize a speaker device capable of significantly improving sound quality with a simple construction. The speaker device applies electromagnetic force to a voice coil based on a supplied audio signal, and generates a sound wave according to the audio signal by vibrating a vibratory plate fixed to the voice coil.

Abstract: An electromagnetic transducer, such as an audio speaker, includes a return path member which is a pole piece for external magnet geometries or a cup for internal magnet geometries. The magnetic flux return path for the primary drive magnet is through a first portion of the return path member. A first section of a low reluctance magnetic flux return path for a secondary drive magnet is through a second portion of the return path member. A magnetically conductive plate provides a second section of the low reluctance return path from the second portion of the return path member to the secondary drive magnet.

Abstract: An electromagnetic sound producing device has a yoke, a coil, a permanent magnet, and a diaphragm provided in a case. The permanent magnet is made of SmFeN-base isotropy plastic magnetic material.

Abstract: An electromagnetic transducer is described including a magnet assembly (50) and a conductive drive coil (52). The magnet assembly provides an emanating magnetic field within which the drive coil is located. The drive coil is a flat ring coil having a width that is equal to or greater than its height. As assembled, the drive coil is mounted in close proximity to the magnet assembly such that relative axial motion may occur between them during use. In one embodiment, the magnet assembly includes two permanent disc magnets (64), (66) having axial magnetizations and being oriented with like poles facing one another to produce a radially emanating magnetic field. In another embodiment, the magnet assembly includes a pair of axially magnetized permanent ring magnets (64), (66) also oriented with like poles facing one another.

Abstract: An electromagnetic drive motor assembly (EDMA) has at least one bridge that extends along a radial direction to conduct heat away from the magnetic gap and towards the outer surface of the EDMA. The EDMA includes a conductive ring between a first plate and a second plate. The conductive ring has an inner ring, an outer ring, and at least one bridge between the inner and outer rings. The inner ring is adapted to receive a voice coil such that the heat generated by the voice coil conducts through the inner ring, the bridge, and then to the outer ring. As such, a heat conducting path is provided within the EDMA to remove the heat away from the voice coil. This allows the EDMA to operate more efficiently. The EDMA may also include a flux return having a pole piece that protrudes from the first plate. The inner ring of the conducting ring may receive the pole piece to form an intermediate gap between the pole piece and the inner ring.

Abstract: An electro-mechanical transducer, including a magnetic assembly producing a magnetic field having two or more displaced regions of greater intensity, having magnetic flux in substantially similar directions, separated by and surrounded by regions of lower intensity magnetic field, and an electrically conductive and mobile member disposed in and capable of moving through a magnetic field.

Abstract: A loudspeaker for generating sound from an electrical current provided by an external source may include an adapter and/or a guide for supporting, directing and routing lead wires carrying the electrical current from the external source. The lead wires may be routed through a guide supported by a pole assembly in the center of the loudspeaker in order to keep the mass associated with the lead wires as near as possible to a moving voice coil former. In this manner, detrimental effects of premature failures and undesirable noise caused by movement of loudspeaker components during operation may be significantly reduced. The guide may include apertures for supporting the lead wires at a desired angle and directing the lead wires toward the external source. Alternatively, or in combination with the aforementioned guide, the lead wires may be routed through an adapter attached to the voice coil former.

Abstract: A speaker driver has a detachable motor and basket to allow attachment or separation of the motor assembly from the basket assembly. Two embodiments are disclosed, a thread-on detachable motor and a bolt-on detachable motor.

Abstract: A magnetic circuit for a speaker comprises: a bottom yoke including a center pole; a ring magnet; a top plate; and a short-circuiting ring shaped like a hollow cylinder. The short-circuiting ring is disposed close and parallel to a voice coil and attached to the inner portion of the bottom of the top plate.

Abstract: The speaker disclosed in this invention comprises: (a) a central cap fixed on voice coil bobbin; (b) a shaft fixed in the center of the central cap; and (c) a bearing filled with lubricating fluid and fixed in a through-hole disposed in the center of a magnetic circuit. The speaker has excellent characteristics without sliding noise or harmful rolling phenomena but with reduced harmonic distortion due to the introduction of a magnetic fluid or a lubricant used as a lubricating fluid.

Abstract: In an electromagnetic induction type speaker apparatus, individual constants are set in such a manner that the following formula is satisfied N×(R1×R2)1/2/(2?×L1×(1?k2)1/2>2000 where R1 is the DC resistance of a primary coil; L1 is the inductance of the primary coil; N is the number of turns of the primary coil; R2 is the DC resistance of the secondary coil; L2 is the inductance of the secondary coil; and k is the coupling coefficient of the primary coil and the secondary coil. In addition, the constants L1 and l2 are selected in such a manner that the ratio of the inductance L1 and the inductance L2 becomes equal to the ratio of the DC resistance R1 and the DC resistance R2.

Abstract: A loudspeaker assembly includes a chassis, a magnet assembly supported by the chassis and disposed at a rear side thereof, a moveable voice coil, a rear suspension, and a diaphragm connected to the voice coil and to the chassis. The assembly defines a voice coil gap receiving the voice coil. To improve the cooling of the assembly, particularly when the magnet assembly includes neodymium, the assembly is positioned at least substantially in front of the diaphragm, and the chassis is positioned outwardly of the magnet assembly. Heat generated by the coil, which could adversely affect the magnet, is dissipated by conduction to the chassis and by convection and radiation to ambient air. The rear suspension supports the voice coil, is secured to the assembly and is connected to the chassis only through the magnet assembly and through the diaphragm.

Abstract: The present invention provides an electromagnetic drive motor assembly (EDMA) that has an inner flux return assembly formed from an upper pole piece and a lower pole piece oppositely disposed relative to each other along the center of the EDMA. An annularly positioned conductive ring (or flux stabilization ring) encircles the inner flux return assembly, concentrically in contact with the outside of the inner flux return assembly. Along the exterior side of the flux return pieces, is a magnet that is between a top plate and a bottom plate. Each plate contacts with the magnet to form a magnetically conductive system. A magnetic gap is formed in between the inner flux return assembly and the top and bottom plates. Disposed within the magnetic gap is a dual coil wound around a cylinder. The dual coil includes a first coil portion and a second coil portion. To minimize the modulation, the top and bottom plates may be saturated and plate tips may be provided near the magnetic gap.

Abstract: An electromagnetic transducer such as an audio speaker, having an improved geometry in the positioning of its voice coils relative to its magnetic air gaps, facilitating a greater linear travel. The transducer has a push-pull geometry with at least two voice coils. At all positions throughout the linear travel region, less than 100% of the total voice coil windings are active, and less than 100% of the total available magnetic air gap height is active. As the voice coil assembly moves in one direction, the percentage of active windings or magnetic air gap is seamlessly handed off from the upper voice coil or magnetic air gap to the lower voice coil or magnetic air gap, and vice versa in the opposite direction. Some of the available voice coil windings and some of the available magnetic air gap height are left unused throughout the linear travel region, but, in exchange, the distance of the linear travel is dramatically increased.

Abstract: A small and high-performance waterproof speaker which can be manufactured inexpensively by decreasing the number of components. Front face of a case (1) is sealed hermetically by a water resistant diaphragm (2) from which a voice coil (3) is projecting inward and a magnetic circuit part (5) having a part (6a) being fitted to the voice coil (3) and a permanent magnet (8) is secured to a first resilient plate (4) provided in the case (1). The first resilient plate (4) is provided with a plurality of through holes (18) and the fitting part (6a) is coupled with the diaphragm (2) through a first coupling member (13) of resilient material. On the other hand, an inertial member (12) is secured to a second resilient plate (11) disposed, oppositely to the first resilient plate (4), in the case (1) and the second resilient plate (11) is coupled with the first resilient plate (4) through a second coupling member (14) of resilient material.

Abstract: A speaker has an annular magnet structure. First and second annular magnets are arranged concentrically with each other and connected by a shunt at one end and a pole-defining structure at the other end to concentrate magnetic flux in a cylindrical voice coil gap. The shunt and pole structure are stacked such that the combined magnetic assembly has an opening extending centrally therethrough. A voice coil rides in the cylindrical magnetic flux gap and its leads are brought out through the opening to the other side of the magnet. When used with an enclosure, the diaphragm of the speaker may communicate through the central opening with the volume of a tuned enclosure extending behind the speaker, or the opening may serve as a port of the enclosure, allowing further degrees of control over total acoustics.

Abstract: A method of correcting a resonance frequency in a vibration speaker generating acoustic sound and vibration includes adjusting the actual resonance frequency to a higher resonance frequency by limiting a predetermined portion of an elastic member installed in a case to an inside of the case to increase the resonance frequency when the actual resonance frequency is not identical to nor less than the desired resonance frequency, thereby adjusting an actual resonance frequency to be identical to a desired resonance frequency, and adjusting the actual resonance frequency to a lower resonance frequency by cutting off another predetermined portion of the elastic member to decrease the resonance frequency when the actual resonance frequency is not identical to nor greater than the desired resonance frequency, thereby adjusting an actual resonance frequency to be identical to a desired resonance frequency.

Abstract: An electromagnetic transducer such as an audio speaker, having a push-push geometry in which there are two or more air gaps and the magnetic flux across the air gaps is in the same orientation. If there are more than one voice coil, the voice coils may thus be generating the same electromagnetic polarity by being wound in the same direction about the bobbin, or by being wound in opposite directions and having separate, opposite polarity electrical connections. The transducer exhibits high linearity over a long travel.

Abstract: A loudspeaker has a diaphragm with a voice coil disposed about its perimeter and extending in a gap into which the flux of an annular rare earth magnet is focused. An opening behind the diaphragm communicates through the speaker frame. The voice coil may have two or more windings that are connected in parallel, and may, e.g., be layered on top of one another, so that the impedance of the coil, as well as its depth in the front/back direction of motion, are low. The voice coil is preferably implemented using a polyamide form or bobbin, which has patterned lead-in conductors embedded therein to bring power to wire windings on the perimeter of the coil. The lead-in conductors extend to, or through, the central opening of a ring magnet, providing a robust ribbon input connection.

Abstract: A vibrator for a bone conduction-type hearing aid device by which sound information is mechanically transmitted via the skull bone directly to the inner ear of a person with impaired hearing. The vibrator includes a coil that is directly into two coil halves for generating a dynamic magnetic field and a permanent magnet for generating a static magnetic field. The permanent magnet is radially magnetized and arranged in such a way that the static and dynamic magnetic fields coincide in air gaps formed between the coil and magnet arrangement and the casing, whereby the vibrator provides an axial force.

Abstract: A loudspeaker comprising a moving coil and a membrane fastened to a chassis, where the membrane is divided into a concentrically disposed inner membrane part and a concentrically disposed outer membrane part, whereby a meeting area is defined between the inner membrane part and the outer membrane part, the inner membrane part being fastened to an inner moving coil and the outer membrane part being fastened to an outer moving coil.

Abstract: A transducer (1) includes a transducer axis (2), a membrane (3), a magnet system (6) having an outer magnet system part (7) and an inner magnet system part (8), a moving coil configuration (27) connected to the membrane (3) and having a coil carrier (28) and a moving coil (29) held by the coil carrier (28) in an air gap (14) between the two magnet system parts (7, 8), and guides (36) for rectilinearly guiding the moving coil configuration (27) parallel to the transducer axis (2). The moving coil configuration (27) has a cylindrical boundary surface (42) which, together with a cylindrical boundary surface (15) of the outer magnet system part (7), delimits a cylindrical gap (43) which is acoustically impermeable above a lower limit frequency of at most 100 Hz.

Abstract: A speaker includes: a frame; a magnetic circuit fixed to the frame; a diaphragm fixed to the frame so as to be capable of vibrating in a predetermined direction; a driving force transmitting member connected to the diaphragm; and a damper for supporting the driving force transmitting member, wherein the magnetic circuit is positioned between a first plane and a second plane, the first plane being parallel to the diaphragm and defined as a plane with which at least a portion of the magnetic circuit is in contact, and the second plane being parallel to the diaphragm and defined as a plane with which at least a portion of the magnetic circuit is in contact, and one end of the damper is connected at a position between the first and second planes, and the other end of the damper is connected at another position between the first and second planes.

Abstract: A method of reproducing audio sound using low level electromagnetism applied to ambient air particles to create a new magnetic field. The method uses a device having at least one winding of electric wires that re wound onto a flexible polymer support. The impedance of the winding is 8 Ohms. The device is connected to an electric audio signal of an acoustic chamber or an acoustic supply. The device and method are useable with audio and audio-video systems, as well as other known methods of communication.

Abstract: An electromagnetic transducer, such as an audio speaker, includes a return path member which is a pole piece for external magnet geometries or a cup for internal magnet geometries. The magnetic flux return path for the primary drive magnet is through a first portion of the return path member. A first section of a low reluctance magnetic flux return path for a secondary drive magnet is through a second portion of the return path member. A magnetically conductive plate provides a second section of the low reluctance return path from the second portion of the return path member to the secondary drive magnet.

Abstract: A planar magnetic transducer having enhanced magnetic structures which increases performance over a single-ended device but mitigates some of the drawbacks of double ended devices, including a supporting structure, a diaphragm incorporating a coil conductor at least a primary magnetic structure, and a secondary magnetic structure can be added, including mitigation of high frequency resonance and attenuation by providing a more open architecture, including spacing the magnets wider apart, configuring the inter-magnet spaces to provide better acoustic performance, using high-energy magnets, which magnets can be shaped to form at least a part of the shaped inter-magnet space.

Abstract: An electromagnetic transducer includes: a first diaphragm; a second diaphragm provided in a central portion of the first diaphragm, the second diaphragm comprising a magnetic material having a first opening in a central portion thereof; a yoke disposed so as to oppose the first diaphragm; a center pole disposed between the yoke and the first diaphragm, wherein the center pole has a shape which allows insertion into the first opening; a coil disposed so as to surround the center pole; and a first magnet disposed so as to surround the coil.

Abstract: An electromagnetic transducer such as an audio speaker exhibiting highly linear performance over a greatly extended excursion. The motor structure includes a stack of two or more magnet and plate pairs, with the magnets polarized in the same orientation such that the magnetic flux flows in the same direction over all of the magnetic air gaps. The voice coil is handed off from gap to gap with a configuration providing a substantially constant BL over an end-to-end distance at least as large as the thickness of one plate plus twice the thickness of one magnet.

Abstract: A speaker arrangement in which a diaphragm does not displace in directions other than a regular oscillating direction. The speaker arrangement includes a magnetic circuit having a magnetic gap, a voice coil located in the magnetic gap, a voice coil bobbin having the voice coil wound thereon, a diaphragm mounted on the voice coil bobbin, a hollow portion extending in a longitudinal direction of the voice coil bobbin and defined inside that portion of the magnetic circuit which is surrounded by the voice coil, an elongated rod inserted in the hollow portion of the magnetic circuit and fixed to the diaphragm, and at least one support member located at a predetermined position in the hollow portion of the magnetic circuit for movably supporting the elongated rod in the magnetic circuit hollow portion.

Abstract: A compound loudspeaker drive unit comprising a first drive unit and a second drive unit arranged co-axial with respect to the center axis of the loudspeaker, and each drive unit comprises permanent magnet means and pole piece means together forming a magnetic circuit with a pole gap for exciting a voice coil assembly, each pole gap providing magnetic field directed radially with respect to a center axis of the loudspeaker. At least one of the permanent magnet means has a radially extending magnetization direction with respect to said center axis of the loudspeaker and the acoustic centers of said drive units substantially coincide.

Abstract: In an electromagnetic induction type speaker apparatus, individual constants are set in such a manner that the following formula is satisfied N×(R1×R2)1/2/{2 ?×L1×(1?k2)1/2}?20000 where R1 is the DC resistance of a primary coil 15: L1 is the inductance of the primary coil 15; N is the number of turns of the primary coil 15; R2 is the DC resistance of the secondary coil 18; L2 is the inductance of the secondary coil 18; and k is the coupling coefficient of the primary coil 15 and the secondary coil 18. In addition, the constants L1 and L2 are selected in such a manner that the ratio of the inductance L1 and the inductance L2 becomes equal to in the ratio of the DC resistance R1 and the DC resistance R2.

Abstract: A speaker for a portable phone capable of being assembled without bonding by adhesives is disclosed. The speaker has a protector having a plurality of sound holes, and having an annular tension extension formed at a periphery thereof and extended upwardly and outwardly; a frame having a stepped portion and a cylindrical wall extended upwardly from the periphery of the stepped portion and having locking means; a diaphragm seated on the stepped portion of the frame and intended to generate sound; a voice coil attached to a lower surface of the diaphragm and adapted to vibrate; a top plate disposed in the voice coil; and a magnet fixedly disposed between the top plate and the frame and adapted to generate a predetermined magnetic field.

Abstract: A speaker and its production method in which productivity can be enhanced and characteristics can be easily improved. A frame 14 of a speaker 10 is divided into a first frame body 15 and a second frame body 44 and the first and second frame bodies 15, 44 can be put together by engaging. A voice coil 35, a magnetic circuit 16 and a damper 17 are attached to the first frame body 15 constituting a first assembly 11. A cone paper 45 is attached to the second frame body 44 constituting a second assembly 12. Claw-shaped hooks formed on the second frame body 44 are to catch an engaging part 21 formed at the first frame body 15 in order to connect the first assembly 11 and the second assembly 12 to construct the speaker 10. The two assemblies 11, 12 can be produced in parallel. This leads to an improvement in the production efficiency.

Abstract: A voice coil actuator is disclosed which provides a proportional solenoid type characteristic and in which first and second magnets are positioned at different ends of a first soft magnetic pole piece and magnetized in opposite directions, the first soft magnetic pole piece having a length greater than the length of the first magnet and the length of the second magnet. A coil having a length less than the lengths of the first soft magnetic pole piece is positioned for travel along an axis common to the first soft magnetic pole piece and first and second magnets, and a structure provides a magnetic path between free ends of the first and second magnets.

Abstract: A loudspeaker has a magnetic flux assembly that has a pole piece and a plate and magnet structure for co-operating with a voice coil. The plate structure includes a top plate which is mounted adjacent to the diaphragm assembly of the loudspeaker. There is a cavity within the voice coil and between the diaphragm membrane and the top of the pole piece. A fluid flow passage is provide to permit air displaced to and from the cavity during movement of the diaphragm assembly to flow through the top plate and to encourage cooling of the assembly.

Abstract: An electromagnetic transducer such as an audio speaker employs a slotted yoke and two suspension components enabling very large excursion relative to the size of the diaphragm which results in improved low frequency output. A first suspension component includes an inner ring, flexible springs, and an outer body. The flexible springs extend through the slots of the yoke and couple the inner ring to the outer body. The inner ring, outer body, and flexible springs of the first suspension component may be of monolithic construction or they may be distinct components coupled together. The inner ring couples to the bobbin of the diaphragm assembly, and the outer body couples to the outer cylindrical surface of the yoke or to a mounting ring which is coupled to the outer cylindrical surface of the yoke. A second suspension component, such as a surround, couples the diaphragm assembly and to the mounting ring.

Abstract: A magnetic circuit for a speaker comprises: a bonded magnet shaped rectangular in top plan view, having on its top face a plurality of grooves formed to extend all the way along two opposing sides thereof and arrayed in parallel with one another at predetermined intervals, and magnetized such that magnetic fluxes at two adjacent grooves are directed inversely to each other; and a plurality of plate-like pole pieces fixedly disposed on the top face of the bonded magnet, and arrayed along the grooves such that two adjacent pole pieces form an air gap located along the center of each groove thereby forming a magnetic gap. And, there is provided a speaker which uses the magnetic circuit thereby achieving a reduced profile.

Abstract: Loudspeaker and other transducers of the dual-voice-coil/dual-magnetic-gap type can be improved by the addition of one or more annular shorting rings strategically located in the vicinity of the two magnetic gaps. The shorting rings have no effect on a steady state magnetic field but act in opposition to any change in flux density or any displacement of the flux lines such as those that occur under the loading imposed when the voice coils are driven hard with audio frequency current. The location of the shorting rings determines their effect: location close to a voice coil reduces the voice coil inductance, location entirely within the magnetic flux loop centerline favors reduction of second harmonic distortion and higher order even harmonic distortion, a centered location on the flux loop centerline, i.e.

Abstract: A loudspeaker includes a bobbin, a coil, a magnetic circuit having a magnetic gap, a first cylinder fixed to the outer surface of the bobbin, a second cylinder connected with the first cylinder, a diaphragm and a damper coupled to the outer circumferential surface of the second cylinder, an edge coupled to the diaphragm, a frame, and terminals. The outer circumference of a yoke constituting the magnetic circuit has a plurality of slits, while the first cylinder and the second cylinder are connected together by a plurality of radially-disposed joints. The loudspeaker has a flat profile yet is compatible with large amplitude and high output power, and capable of reproducing a wide range of sounds from a low tone to a high tone.

Abstract: A loudspeaker includes: a bottom plate; a center pole provided upwardly from the bottom plate; a yoke surrounding the center pole and having a plurality of slits; a magnet for providing a magnetic flux for the center pole and the yoke; a coil provided between the center pole and the yoke; a first annular member for supporting the coil; a plurality of support members for supporting the first annular member, the plurality of support members being inserted into the plurality of slits; and a diaphragm supported by the plurality of support members, wherein upper faces of the plurality of support members gradually decrease in height in a direction away from the first annular member, and wherein a lower face of the coil is located below a position at which the diaphragm is supported by the plurality of support members.

Abstract: The assembly comprises a loudspeaker drive unit having terminals for connection to an audio signal source. The drive unit has a chassis with a mounting ring which has first and second opposed surfaces for, respectively, abutment against a seating in a mounting ring and abutment by a retaining circlip. The mounting ring is retained in an aperture in, for example, a ceiling by spring clips. The design of the drive unit allows it to be substituted for the sealed halogen light bulb in a conventional light fitting having such a bulb. A simple and convenient way of mounting the loudspeaker, particularly in a ceiling in a room such as a kitchen or bathroom where space elsewhere is limited, is therefore provided. The invention also facilitates conversion between a light fitting to a speaker installation.