Abstract: A loudspeaker comprising at least one magnet 27, yoke 24 fixed to a bottom surface of the magnet, flat plate 26 fixed on an upper surface of the magnet, magnetic circuit 29 having magnetic gap 28 formed between the plate and the yoke, and flat diaphragm 23 provided with coil 21 disposed above the magnetic gap. The magnet has a width greater than that of the plate, and at least a part of the upper surface of magnet is exposed so that it faces directly to the diaphragm. According to the structure of the present invention, a larger volume magnet can be used without increasing a size of the magnetic circuit. Furthermore, as magnetic flux can be concentrated to an upper region of the magnetic gap, the magnetic circuit becomes efficient and compact. Thus a compact and high-efficiency loudspeaker for high frequency sounds reproduction can be provided.

Abstract: An electroacoustic transducer comprising a magnetic circuit of a magnetically conductive material with a pair of opposed surfaces defining a gap there between, the magnetic circuit comprising one magnet. The magnet can either be positioned in the centre of the magnetically conductive material so as to form two gaps. In an alternative embodiment the magnet is attached to the magnetic conductive material forming only one gap. The transducer further comprises a diaphragm and a coil system having electrically conducting paths fastened to the diaphragm. The coil system has portions of its paths situated in the gap. The transducer may be supplied with an additional diaphragm and coil system positioned on the opposite side of the magnetic circuit. In a preferred embodiment the transducer is rectangular. The transducer is suited for integration into miniature components such as mobile communication equipment and hearing aids.

Abstract: A mechanical resonance frequency of vibration section 13 of an electro-acoustic transducer having vibrating function is measured during assembly process and is compared with a predetermined mechanical resonance frequency. Based on a difference obtained by the comparison, one of an weight of weight 14 to be attached and a position for fixing the vibration section to frame 16 is determined. In accordance with the determination, the weight 14 for resonance frequency adjustment is attached to vibration section 13, or suspension 12 and frame 16 which have been provisionally fixed are fixed again. Thus the predetermined mechanical resonance frequency f0 can be obtained steadily. As a result, the rectro-acoustic transducers having vibrating function with stabilized mechanical resonance frequency of the vibration section 13 can be produced.

Abstract: A system for tensioning a membrane within a frame for a loudspeaker or a microphone is characterized by a frame containing an opening, a membrane connected to an exterior surface of the frame and spanning the frame opening, and a tensioning device connected with the frame for deflecting a portion of the membrane within the frame opening. The tensioning device is compliant thereby allowing the membrane to exhibit a high degree of flexure both within and beyond a plane containing the membrane.

Abstract: A speaker includes a diaphragm having a central aperture at which a bobbin with a voice coil wound therearound is mounted, and mounted at the outer periphery thereof on a frame with an edge therebetween, and a magnetic circuit section that has a magnetic gap in which the bobbin is placed, and that drives the diaphragm to vibrate in the frontward and rearward direction. The speaker can use a larger diaphragm by providing the frame with an edge-mounting portion on which the edge is mounted, and a portion formed in front of the edge-mounting portion.

Abstract: A loudspeaker system comprises a flexible paper or plastics diaphragm 1 for displacing a quantity of a transmitting medium to generate sound, waveform-sampling circuitry for supplying a series of sample drive signals of varying amplitude indicative of the amplitudes of an electrical input signal having an audio waveform

Abstract: A diaphragm subassembly comprises a voice coil, a diaphragm, a frame, and a pair of terminal members. A magnetic circuit unit comprises a yoke, a magnet, and a base. The diaphragm subassembly and the magnetic circuit unit are accommodated in a bottomed cylindrical cover. In the manufacturing process, the cover is placed with the open end directed upward. The diaphragm subassembly, the yoke, the magnet, and the base are dropped into the cover in this order. The manufacturing process of a dynamic electroacoustic transducer is thereby simplified.

Abstract: A loudspeaker includes: a frame; a vibrating section including a diaphragm having an internal periphery and an external periphery, a voice coil attached to the internal periphery of the diaphragm, a spider which connects the voice coil to the frame, and a dust cap attached to the internal periphery of the diaphragm; and a surround which connects the external periphery of the diaphragm to the frame, wherein the ratio between the weight of the vibrating section and the weight of the surround is 0.9:1 to 1.5:1.

Abstract: An electroacoustic transducer (1) has a membrane (19), which has a membrane axis (5) and a ring-shaped pleats area (22), the pleats area (22) being provided with a multitude of pleats (26, 27, 28, 32, 33, 34, 38, 39, 40), in which diametrically opposed pleats are embodied differently with regard to at least one of the pleat parameters.

Abstract: A spider-less and suspension-less speaker system, having a diaphragm constrained to move in a linear direction and supported by a frictionless or low friction support. A voice coil coupled to an audio input drives the speaker diaphragm. A position sensor determines the physical position of the diaphragm. A control circuit uses the sensed position information to modify the audio signal in such a way that the interaction of the voice coil and the magnetic field both drives the diaphragm to produce an audible output and restores the diaphragm to a neutral position in the absence of a further audio signal.

Abstract: Electro-dynamic loudspeakers typically include a diaphragm having a conductor applied to one of its surfaces. The diaphragm is secured to a frame. The conductor is connected to a power supply for providing electrical current through linear traces of the conductor that interact with magnetic fields generated by magnets that are mounted to the frame. The diaphragm is driven by a motive force created when current passes through the conductor within the magnetic field. The electrical current is varied to create an acoustical output from the electro-dynamic loudspeaker. Different methods of tensioning the diaphragm are provided for simplifying the manufacturing process and for assuring proper diaphragm tension.

Abstract: Trace runs for Planar Line Source Transducers (or speakers) are separated into multiple trace circuits which are electrically isolated but occupy the same area on the planar film. The separate trace runs are then driven with different electrical signals with tailored spectral content in order to achieve an overall acoustical frequency response. By having the separate trace runs occupy the same area, the line source nature of the transducer is preserved over the entire intended spectral response of the transducer and the mechanical structure is also kept simple. External spectral filtering circuits are used to pre-shape the spectral signal into each individual trace run and in most cases, the filtering components are passive and inexpensive.

Abstract: Electro-dynamic loudspeakers typically include a diaphragm having a conductor applied to one of its surfaces where the diaphragm is secured to a frame. The conductor is connected to a power supply for providing electrical current through linear traces of the conductor that interact with magnetic fields generated by magnets that are mounted to the frame. The diaphragm is driven by a motive force created when current passes through the conductor within the magnetic field. The electrical current is varied to create an acoustical output from the electro-dynamic loudspeaker. Different methods of attaching the diaphragm are provided for simplifying the manufacturing process and for obtaining a robust electro-dynamic loudspeaker.

Abstract: Electro-dynamic loudspeakers typically include a diaphragm having a conductor applied to one of its surfaces. The diaphragm is secured to a frame. The conductor is connected to a power supply for providing electrical current through linear traces of the conductor that interact with magnetic fields generated by magnets that are mounted to the frame. The diaphragm is driven by a motive force created when current passes through the conductor within the magnetic field. The electrical current is varied to create an acoustical output from the electro-dynamic loudspeaker. Different frame structures are provided for simplifying the manufacturing process and defining a reduced cost electro-dynamic loudspeaker.

Abstract: An electro-dynamic loudspeaker includes a frame, a plurality of magnets and a diaphragm. The frame includes a molded plastic body. The magnets may be molded into the frame in a determined configuration. The frame is mechanically coupled to the diaphragm such that the magnets are a determined distance from the diaphragm. The diaphragm may include a conductor applied to a surface of the diaphragm. The diaphragm may be driven by a motive force created when current passes through the conductor within a magnetic field formed by the magnets. The electrical current may be varied to create an acoustical output from the electro-dynamic loudspeaker.

Abstract: The present invention provides a loudspeaker having double symmetric magnet-circuits, double voice coils and double dampers. The loudspeaker comprises a diaphragm holder, a diaphragm, an upper and a lower dampers, an annular steel magnet, a core, voice coils, an upper and a lower plate. Wherein the core is a steel magnet, the polarities of its upper and lower ends being opposite to those of the upper and lower ends of the annular steel magnet, so are two symmetric and parallel magnet-circuits formed. Thus the intensity of the magnet field in the two magnet gaps became very high because of the two magnet sources, so is the high power loudspeaker able to work normally.

Abstract: An electro-dynamic loudspeaker is provided with dampening arrangements that contribute to improved acoustical properties for the electro-dynamic planar loudspeaker. The dampening arrangements include providing a frame having a curved sidewall surface for reducing standing waves. Another design provides for a ferrofluid being disposed between the diaphragm and magnets of the electro-dynamic loudspeaker in order to dampen the resonance frequency of the device. In addition, a diaphragm of an electro-dynamic loudspeaker is provided with a short turn of conductor disposed along a fringe zone at an edge of the diaphragm in order to electro-dynamically dampen the edge resonance of the film.

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: A symmetrically loaded, shallow suspension speaker with stiff diaphragm having a minimum dimension that is greater than the diameter of the magnet that drives the diaphragm thus allowing the suspension of the diaphragm to extend nearly to the bottom of the speaker basket on the maximum inward excursion of the voice coil and diaphragm such that the suspension operational depth is not the limiting factor of the overall height of the speaker. The elements of the suspension system are designed to maximize the spacing between the inner and outer portions of the suspension, thus minimizing the possibility of wobble in the speaker. The speaker design maximizes air movement in a given mounting depth with a configuration that optimizes the operation of the moving parts that complements the fixed mechanical structural configuration of the non-moving parts in either an overhung or underhung configuration. The design also accommodates user replacement of the voice coil or cone.

Abstract: A linearly compliant, flexible, resilient and flat speaker damper connected between the frame and the cone of the speaker with electrically conductive paths applied to the damper to conduct the signal to be applied to the voice coil of the speaker. A method for linearly compliant audio speaker damping and a method for application of voice coil conductors on the damper.

Abstract: The surrounding structure of the loudspeaker forms an annular structure, including attaching parts and curved part. The cross section of the curved part is in a hollow and approximately elliptical form. The height along the major axis of the ellipse is made parallel to the center axis of the vibrating diaphragm of the loudspeaker while the width along the major axis of the ellipse is set in the direction orthogonal to the center axis of the vibrating diaphragm. In the elliptical surrounding structure having such a structure, the width in the cross section of the surrounding structure of the loudspeaker can be made narrow in comparison with a semi-circular surround, whereby the linearity of the amplitude and the maximum displacement are increased.

Abstract: An improved speaker having a modified front plate with air intake apertures, a vented frame, and a voice coil supported by a diaphragm constructed of gas impermeable material connected at one end to the frame and at the other end to the voice coil. Operation of the voice coil causes the diaphragm to draw air through the air intake apertures where it is drawn past the voice coil and vented out through the frame. The diaphragm operates as an air pump forcing the air past the voice coil for supplying of cool are and exhausting of heated air. A unidirectional flap may be used on the vented frame to an create air flow current past the voice coil for higher efficiency. The improved speaker provides longevity to the voice coil, the voice coil to diaphragm coupling, and to the diaphragm itself.

Abstract: A loudspeaker of the present invention includes a diaphragm; a voice coil for driving the diaphragm; and a magnetic circuit including a yoke, a magnet provided on the yoke, and an upper plate provided on the magnet, for producing a magnet field that is perpendicular to the voice coil. The upper plate has a surface configuration such that when reflecting sound waves created by the diaphragm, the upper plate diffuses the sound waves.

Abstract: A speaker includes a disk-shaped base. A substantially hemispherical surface vibrator is fitted into a substantially circular groove formed in the base to be bonded therein. Terminals are attached to electrodes located on both surfaces of the vibrator. The edge portion of the vibrator is bonded with a first adhesive, and further, its circumference is bonded with a second adhesive. The first adhesive has a sufficient bonding strength between the vibrator and the base. The second adhesive has a lower elastic modulus than the first adhesive.

Abstract: A speaker apparatus is provided. A frame has a projecting portion projecting toward a diaphragm at the periphery of the frame. The diaphragm has a rising portion extending opposite to the frame from the periphery of the diaphragm and having an outside surface along an inside surface of the frame projecting portion. The outside surface of the rising portion is adhered to the inside surface of the frame projecting portion.

Abstract: An edge damper frame 18b is disposed in between a part of an outer peripheral surface 20a of a frame-cover 20 and a leveling surface 14c-1 of a frame 14. A slope 18e of a diaphragm 15 is extended from the edge damper frame 18b toward the frame 14 and provided alongside an outer side surface 14c-2 of a convex portion 14c of the frame 14.

Abstract: An electroacoustic transducer, functioning as an acoustic pick-up or as a sound generator, has a housing having a bottom and a wall portion. A diaphragm is connected to the housing opposite the bottom and encloses a diaphragm volume. An electromagnetic system is arranged in the housing and has a coil connected to the diaphragm. The housing has at least one cutout cooperating with at least one projection provided on a device in which the electroacoustic transducer is to be mounted. The projection defines a passage between the diaphragm volume and a volume at the back of the housing and thus forms the main air passage.

Abstract: The invention provides a speaker having a number of features that cooperate to provide a small speaker 10 having a high sound pressure level output capability (volume), a wide frequency range, in particular from below 200 Hz to 20,000 Hz, low distortion, and that is magnetically shielded. The speaker 10 is suitable for mounting in, for example, a television where spaces are confined and stray magnetic fields are undesirable, yet high output is desirable and a wide frequency range is desirable to avoid the need for separate middle frequency (midrange) and high frequency (tweeter) speakers.

Abstract: A speaker has a frame made of resin, a diaphragm provided in the frame, a voice coil mounted on the diaphragm. A pair of holes are formed under the diaphragm so as to be opened at an underside of the frame. A spring is connecting member provided in each of the holes to be projected from the underside of the frame, and connected to an end of the voice coil.

Abstract: An ultra low frequency transducer or subwoofer for automotive speaker systems with a rectangular or square, concave diaphragm. The square periphery preferably is sized to be substantially coextensive with the front of the speaker housing or cabinet. In this way, air displacement in the subwoofer is maximized for a given size of enclosure, and thus so is the loudness of the speaker. The transducer typically includes a frame or basket with a square front for supporting the periphery of the diaphragm. The preferred diaphragm includes a convex surround with pleated corners. For increased durability, trusses are formed in the diaphragm.

Abstract: 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.

Abstract: A high efficiency loudspeaker without a damper is provided. The loudspeaker includes magnetic circuit 9 having magnetic gap 14 and voice coil member 15, which has movable coil 16, disposed in magnetic gap 14 of magnetic circuit 9. The loudspeaker also includes diaphragm 17, whose inner peripheral part is linked with voice coil member 15, outside magnetic gap 14 and frame 19 linked with an outer peripheral part of diaphragm 17 via first edge 18. An inner peripheral part of suspension holder 20 is linked with voice coil member 15 at a linked position, which is nearer to magnetic circuit 9 than a linked position of diaphragm 17 and voice coil member 15. An outer peripheral part of suspension holder 20 is linked with frame 19 via second edge 21. First edge 18 and second edge 21 are substantially symmetrical analog each other about a median of first edge 18 and second edge 21.

Abstract: The outer peripheral site of a loudspeaker unit is provided with predetermined air passages formed along substantially the overall inner perimeter of an opening in a baffle plate for allowing a communication between the interior and the exterior of an enclosure, whereby there is provided a loudspeaker system capable of achieving, e.g., improvements in low-frequency characteristics and in transient characteristics while implementing reductions in size and weight.

Abstract: A passive radiator and method is disclosed which improves frequency response linearity and greatly reduces the possibility that wobble of a passive radiator which will occur without the displacement limitations of a spider containing speaker structure. Two substantially flat surfaced speaker diaphragms are tied together and supported by two sets of surrounds oriented in opposite directions to reduce the non-linearity in the surround spring rate and improve low frequency sound generation. A vent (pressure relief) system is provided to improve the frequency response and range of motion of the passive speaker system. A progressive surround roll arrangement provides for improved sound quality by utilizing localized position based extension while maintaining the range of maximum travel during resonance.

Abstract: An ultra low frequency transducer or subwoofer for automotive speaker systems with a rectangular or square, concave diaphragm. The square periphery preferably is sized to be substantially coextensive with the front of the speaker housing or cabinet. In this way, air displacement in the subwoofer is maximized for a given size of enclosure, and thus so is the loudness of the speaker. The transducer typically includes a frame or basket with a square front for supporting the periphery of the diaphragm. The preferred diaphragm includes a convex surround with pleated corners. For increased durability, trusses are formed in the diaphragm.

Abstract: A speaker comprises: a magnetic circuit composed of a pot yoke, a magnet, and a pole piece; a diaphragm shaped conical, defining an outer periphery and an inner periphery, and having a surround half-rolled and fixedly disposed at the outer periphery and a voice coil bobbin with a voice coil wound thereon fixedly disposed at the inner periphery; a spider having an outer diameter equal to or larger than the outer diameter of the surround; a frame having the magnetic circuit fixedly disposed at its central opening; and a spacer ring fixedly disposed inside the frame, and having a surround edge receiving portion adapted to fixedly receive the entire outer edge of the surround thereon.

Abstract: A holder 1 is provided with two first engaging frame parts 2 and 3 and one second engaging frame part 4. The second engaging frame part 4 includes a pair of supporting parts 41, an elastic beam part 42, and an operating piece 44. The elastic beam part 42 is bendable outward and twistable. A width of the opening of the second engaging frame part 4 is shorter than the sum of a thickness of a flange 61 and a thickness of an edge frame member 62. When the elastic beam part 42 is twisted, the opening width of the second engaging frame part 4 is increased, and the elastic beam part 42 comes in engagement with the rear surface of the flange 61.

Abstract: A mid/high frequency loudspeaker comprising a stiff lightweight resonant panel form member, a housing in which the panel form member is mounted, a suspension connected between the edges of the panel-form member and the housing and by means of which the panel edges are restrained against movement, the arrangement being such that the housing and the panel-form member together define a cavity, and an electrodynamic exciter for applying bending wave energy to the panel-form member to cause it to resonate to produce an acoustic output, the exciter comprising a magnet assembly rigidly fixed to the housing and defining an annular gap, and a voice coil and coil former assembly disposed in the annular gap and rigidly fixed to the panel-form member near to the geometric center thereof, wherein only said panel suspension centers the voice coil and coil former assembly in the annular gap.

Abstract: A loudspeaker has a cylindrical frame, a magnetic circuit formed on the frame, a voice coil disposed in a magnetic gap of the magnetic circuit, a diaphragm. A damper is attached to the frame and supports the voice coil. Leads are connected to both ends of the voice coil. The leads are attached to the damper by stitching.

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: An electroacoustic transducer (1) has a membrane (19), which has a membrane axis (5) and a ring-shaped pleats area (22), with the pleats area (22) being provided with a multitude of pleats (26, 27, 28, 32, 33, 34, 38, 39, 40), with diametrically opposed pleats being embodied differently with regard to at least one of the pleat parameters.

Abstract: The problem of providing an electroacoustic converter for wide-band loudspeakers or magnetless electrodynamic headphones for generating sound, in particular for application in the homogeneous and/or nonhomogeneous magnetic field of a magnetic resonance tomograph, an electroacoustic converter avoiding the drawbacks of the prior art, is essentially resolved in that the electroacoustic converter for generating sound comprises an elastically suspended oscillating body, whereby the oscillating body consists of a non-elastic or low-elastic, non-magnetic or only weakly magnetic material and is flatly and in a fixed manner connected with conductor paths, on which a Lorentz force is acting as the driving force when current is flowing. The Lorentz force is supplied by the magnetic field of the magnetic resonance tomograph.

Abstract: The present invention is a spring suspension speaker that will virtually eliminate failure of the speaker due to fatigue from cyclic stress from regular use of the speaker or due to a surge of power to the speaker. The present invention comprises of a flexible support member installed within the conventional speaker. The present invention improves the performance and the life expectancy of the conventional speaker and also improves the responsiveness of the speaker, thereby increase the accuracy of the sound reproduced by the speaker.

Abstract: A system for tensioning a membrane within a frame for a loudspeaker or a microphone is characterized by a frame containing an opening, a membrane connected to an exterior surface of the frame and spanning the frame opening, and a tensioning device connected with the frame for deflecting a portion of the membrane within the frame opening. The tensioning device is compliant thereby allowing the membrane to exhibit a high degree of flexure both within and beyond a plane containing the membrane.

Abstract: A surround is for use in an electron-dynamic acoustical transducer. The electron-dynamic acoustical transducer includes a frame, a diaphragm and a voice coil. The surround includes a single, large, semi-circular corrugation that is constructed from compressed neoprene foam rubber and secured to the frame by the surround. The surround has a plurality of radially distributed, relatively less-compressed areas.

Abstract: An electroacoustic transducer which has at least one stator member with an operating surface and a suspended emitter diaphragm spaced from the operating surface of the stator member to enable the diaphragm to oscillate in response to an applied signal voltage. The diaphragm has increased stiffness in a direction along the diaphragm and within the emitter section to enable the emitter diaphragm to oscillate without applying tension in the direction of stiffness. A clamp member secures the diaphragm to maintain the diaphragm in a fixed position relative to the stator to minimize distortion. The clamp member is positioned to define at least two isolated emitter sections for enhancing the frequency response of the transducer. A method is also provided for generating audio output from an electroacoustic transducer.

Abstract: A suspension molded from a rubber compound in a molding through a foaming process, having solid top and bottom covering layers that do not admit light, and a foamed intermediate layer integrated in between the solid covering layers.

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 loudspeaker includes a magnetic circuit comprising a center plate, first and second magnets disposed respectively on a lower surface and an upper surface of the center plate and magnetized to be repulsive to each other, an under plate disposed at a lower surface of the first magnet, and a yoke. The loudspeaker further comprises a voice coil, a diaphragm, an edge coupled with the outer circumferential edge of the diaphragm, and a frame. The above-described magnetic circuit further comprises a top plate disposed on an upper surface of the second magnet. Both of the second magnet and the top plate have a ring shape, the inner and the outer diameters of the second magnet and the top plate being substantially the same. Outer diameters of the second magnet and the top plate are smaller than that of the center plate, and the center plate is provided on its upper surface with a protrusion for positioning of the second magnet.

Abstract: An electrodynamic loudspeaker comprising a chassis (2), a three-dimensional diaphragm (8) and an electromagnetic actuator (6). The diaphragm is connected to the chassis by a first flexible connecting means (18) provided near a front part (8a) of the diaphragm and by a second flexible connecting means (20) provided near a back part (8b) of the diaphragm. The actuator includes a stationary actuator element (6a) fixed to the chassis and a translatable actuator element (6b) fixed to the diaphragm. When energized, both actuator elements magnetically co-operate with one another over an air gap (16). In order to realize a flat but powerful speaker, the device as such and the air gap are outside the area (26) enclosed by the diaphragm but within the space (24) between both connecting means.