Abstract: The invention concerns a method for making a material absorbing surface mechanical wave generated by local waves capable of producing interference phenomena relative to the pressure wave with propagation direction orthogonal to said surface. The method consists in forming a support (S) delimiting the surface from a continuous structure, said support having a specific rigidity in a direction substantially orthogonal to said support (S). An sound-absorbing coat (R) is then formed on at least one surface of the support (S), said coat comprising a plurality of obstacles to the propagation of the surface mechanical wave and the local waves, which are thus absorbed. The invention is useful for making diaphragms for electro-acoustic transducers and high quality electro-acoustic transducers.

Abstract: A frame (14) supporting a diaphragm (12) by its outer periphery is constructed by a connecting ring (30) and a base (28) which comprises a bottomed cylinder portion (28A) and a mounting portion (28B) which extends radially outward from the bottomed cylinder portion (28A) which is a part of the magnetic circuit unit (18). The connection is achieved by the caulking of the ring (30) and the mounting portion (28B) with the diaphragm (12) clamped therebetween.

Abstract: A diaphragm of electroacoustic transducer has an edge formed with alternately up-rolled and down-rolled portions with respect to vibration plane of the diaphragm and disposed at regular intervals in circumferential direction and with sloped-plane portions respectively connecting rims opposing above and below of adjacent ones of the up-rolled and down-rolled portions, the sloped-plane portions extending in respective tangential lines with respect to an inner periphery of the edge and intersecting the circumferential direction at an alternately opposite angle with respect to the vibration plane.

Abstract: A flat panel sound radiator system for installation in a suspended ceiling is disclosed. The system is capable of concealing a modular sound radiator so that it appears substantially the same as surrounding ceiling panels. In this way the monolithic appearance of the ceiling is not interrupted. The assembly comprises a frame and a radiating panel resting within the frame and an acoustic facing covering the panel that is substantially indistinguishable from surrounding ceiling panels. Additionally disclosed is a ceiling system including a grid, a plurality of ceiling panels and an acoustical radiator having an acoustical visually matched exposed layer.

Abstract: The invention relates to the embodiment of panel loudspeakers 10 working according to the bending wave principle. Such loudspeakers 10 generally consist of an acoustic panel 11 and drivers 12, whereby the drivers 12 are connected to the acoustic panel 11. For the formation of bending waves in the acoustic panel 11, it is essentially important that the drivers 12 do not unnecessarily rigidize the acoustic panel 11. This has led to the arrangement of the drivers 12 at a distance from the acoustic panel 11 in a separate frame. In view of the complexity of such an arrangement, the invention aims at providing a connection between the drivers 12 and the acoustic panel 11 that can be supported directly on the acoustic panel 11 and which does not impede the propagation of the bending waves. This is achieved by connecting the drivers to the acoustic panel only at very few points 24 or by providing elastic member 25 in the fixing area of the drivers. A combination of both embodiments is also described.

Abstract: Acoustic devices rely on bending wave action in a panel member, particularly distribution of resonant modes of such bending wave action and related acoustically significant surface vibration over area of said panel member favourable to desired or at least acceptable acoustic device performance. The devices comply with selecting parameters of said panel member affecting said distribution, including configuration/geometry and/or bending stiffness(es), and/or location(s) of bending wave transducer(s) in said area of said panel member; the selecting being in accordance with analytical assessment of power transfer related characteristic(s) of said panel member thus said acoustic device concerned and desiderata therefor correlating with achieving said acoustic device performance.

Abstract: A flat panel rectangular or elliptical loudspeaker has one or more anisotropic diaphragms 14, 15, made of double skinned fluted polypropylene copolymer (core flute) or corrugated cardboards having a longitudinal bending strength greater than the transverse bending strength. The diaphragm is vibrated by a driver unit 16 which comprises a magnet 17 and voice coil 18. In this version the magnet 17 is mounted on the rear diaphragm 15 and the voice coil 18 is mounted on the front diaphragm 14. The two diaphragms 14, 15 are mounted at their edges to a frame 11 with the driver unit 16 mounted in the space enclosed by the frame and the diaphragms.

Abstract: An apparatus for mounting a flat panel radiator into a ceiling grid. The ceiling grid system includes openings defined by main beams and crossbeams. The main beams are secured through hanger wires to a hard ceiling. The main beams and the crossbeams have flanges with the crossbeams resting on the flanges of the main beams. The mounting apparatus has a frame including a top plate, a side plate, and a bottom plate, containment elements and isolation elements attached to the frame, and an acoustically transparent scrim attached to the bottom of the frame. The flat panel radiator is mounted between containment elements and isolation elements. The radiator panel can be fabricated from a honeycomb core. The containment elements may be made from a stiff to resilient material, whereas the isolation element will always be resilient to vibration isolate the radiator panel from the ceiling grid system both mechanically and acoustically. The flat panel sound radiator assembly can also be installed in wall partitions.

Abstract: An electroacoustic transducer with attenuated effective output irregularities caused by intrinsic normal modes of oscillation. What stands out, as a structural property of a preferred embodiment, is a sandwich assembly, having an oscillating medium of layered components suspended between two rigid baffles, with a hinged baffle extension supporting the device in upright position. An opening, asymmetrically positioned in each of said two rigid baffles, exposes to the ambient medium a driven and asymmetrically positioned antinode belonging to a predetermined mode pattern of the oscillating medium. The resulting asymmetrical and partial coupling of the oscillating medium with the ambient medium limits occurrences of irregularities in effective output. Similarly, the asymmetrical and partial driving of the oscillating medium leads to a relatively high number of normal modes simultaneously excited.

Abstract: The invention concerns a loudspeaker having an elongate parallelepiped hollow body, whereof one longitudinal surface is made up of a stretched elongate rectangular planar diaphragm. The diaphragm is suspended by its edges to the body adjacent side surfaces, and is integral with an elongate rigid inner part extending in the body longitudinal direction, and bearing a mobile electromagnetic coil, parallel to the diaphragm. The coil is arranged between two fixed magnets located along the body two longitudinal side surfaces which form, with the base of said body, polar parts. Said loudspeaker is useful as component of an active anti-noise system, associated with a double glazing.

Abstract: A diaphragm for a speaker and a speaker device, a frequency characteristic as well as the endurance against input of which are improved, have been provided. A convexo-concave portion is radially formed at a neck of the diaphragm, which is stuck to a voice coil bobbin, to increase an adhesion area of the neck itself, thereby the endurance against input is improved. In addition, the neck is stuck to the voice coil bobbin by an adhesive to increase the mechanical strength of the neck itself, thereby a frequency characteristic as well as the endurance against input are improved.

Abstract: A panel-form loudspeaker has a resonant multi-mode radiator panel which is excited at frequencies above the fundamental frequency and the coincidence frequency of the panel to provide high radiation efficiency through multi-modal motions within the panel, in contrast to the pistonic motions required of conventional loudspeakers. The radiator panel is skinned composite with a honeycomb or similar core and must be such that it has a ratio of bending stiffness to the third power of panel mass per unit area (in mks units) of at least 10 and preferably at least 100. An aluminum skinned, aluminum honeycomb cored composite can meet this more severe criterion easily.

Abstract: The invention herein of a standard-sized Vibrating Diaphragm speaker structure, primarily includes a stand with an enlarged opening in the front and a magnetic element in the rear, a cylinder inside a magnetic element, a spring panel sticking with a cylinder, and a Vibrating Diaphragm located on the enlarged opening of the stand. The inner face of Vibrating Diaphragm sticks with cylinder. The improved structure of the invention is characterized as that the surface of Vibrating Diaphragm is free of end fixture and it sticks with a foam washer, which is located at the lower portion of Vibrating Diaphragm and is stuck with an enlarged opening of a stand. Thus, the effective vibration area for a Vibrating Diaphragm is maximized and the output of sound magnitude for a speaker is enhanced. A foam washer substitutes the function of flexible movement for an end fixture of the invention of prior art to achieve normal sound output of a speaker.

Abstract: A speaker device has a first plate and a second plate disposed behind the first plate. A speaker membrane is disposed between the plates electrically coupled to a driver which supplies an electric signal causing the membrane to vibrate and create sound waves. The first and second plate have a first and second pattern, respectively, of regularly spaced and similarly sized openings. The openings of the first and second patterns may be similarly sized and spaced or the openings of the first pattern may be larger and spaced further apart than the openings of the second pattern. A support structure joins the first and second plates together in a fixed, spaced relationship and at a relative positional orientation, or at a relative rotational orientation. The orientation of the plates develops a repeating pattern of recurring geometric images.

Abstract: A passive radiator assembly for a speaker that substantially reduces diaphragm resonance in the operating frequency range of the device. The new passive radiator assembly includes a quasi-elliptical shaped laminated honeycomb diaphragm, which is damped by an integral outer compliance (suspension) made of an elastomeric material that covers the entire upper surface of the diaphragm. The integrated outer compliance is of a progressive type, having a stiffness that increases in a controlled fashion during large excursions. To prevent non-linear rocking movements and compensate for displacement non-linearities, at least one, and preferably two, opposed spiders supported by a spider assembly frame are used to provide a restoring force applied to the diaphragm.

Abstract: An electroacoustic transducer (1) having a voice coil (17) and having a diaphragm (19) with an annular intermediate zone (22) for securing the voice coil (17), the intermediate zone (22) having angularly spaced-apart trough portions (29) which are each bounded by a trough bottom wall (30) and two trough side walls (31, 32), and the voice coil (17) being secured to the trough bottom walls (30).

Abstract: The invention relates to acoustic walls for large public events. Traditionally, sound is reproduced by using a plurality of large and heavy loudspeaker boxes which requires a complicated and expensive support system. The present invention provides a segmented acoustic wall which has an essentially flat shape and is also extremely lightweight. Several of these segments can be integrated to form an acoustic wall by coupling the different segments with one another, whereby the entire surface area of the acoustic wall can be used to radiate sound without requiring additional sound sources in the audience space. The various segments can be optimized for certain frequency ranges by tuning the surface area and depth of the respective segments to the respective transmitted frequencies. Several acoustic walls can be placed side-by-side to flexibly conform to different requirements in the audience space.

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.

Abstract: A method for manufacturing a speaker diaphragm comprising the steps of forming a plurality of virtual concentric circles between central point of a circle having a predetermined size and a circumference thereof; dividing said each concentric circle with a predetermined angle, forming divided points on the circumference of each concentric circle and arranging a plurality of yarns from a point on the circumference of said circle to another point thereof to come in tangential contact with said divided points, thereby forming a omnidirectional pseudo-textile fabric; thermosetting said pseudo-textile fabric; and removing a gap formed on said pseudo-textile fabric using a resin, a film or a sheet.

Abstract: The present invention is directed to an improved high frequency acoustic speaker center cone, which may be located at a speaker coil tubular support, tube wherein the cone has a plurality of thin, pie-shaped segments radiating outwardly with each of the segments having an arcuated cross-section, so as to create a convex shape towards its center. The segments are highly concave toward the center and less concave with increasing radial distance away from the center. The width of the segments may increase linearly with radial distance so as to create a constant acoustical resistance radially. The center cone also has a thickness gradient with increasing thickness radially towards its center. In another embodiment, the present invention is directed to a system containing both the aforesaid center cone, an outer cone with similar radial characteristics but being concave towards its center. The segments of the outer cone preferably terminate at a flexible, high sound absorption ring.

Abstract: A device for electroacoustic diffusion includes a basket; a balance supported by the basket, made of balsa wood or formed with a balsa wood stripe fixed at its ends with a coil glued at its middle; a balsa wood membrane supported by the basket; a suspension adjacent to the membrane and supported by the basket; and an electroacoustic structure adjacent the basket and opposite the balance. The electroacoustic structure includes a first plate adjacent the basket, a second plate, a magnet between the first plate and the second plate, and a coil between the first plate and the second plate. The membrane can take on various shapes, including: (a) a truncated-cone shape, including triangular pieces of balsa wood, steam folded, glued, and placed with fibers of the balsa wood in a radial orientation, (b) a dome-shape, and (c) a planar shape.

Abstract: The present invention is directed to an improved high frequency acoustic speaker center cone, which may be located at a speaker coil tubular support, tube wherein the cone has a plurality of thin, pie-shaped segments radiating outwardly with each of the segments having an arcuated cross-section, so as to create a convex shape towards its center. The segments are highly concave toward the center and less concave with increasing radial distance away from the center. The width of the segments may increase linearly with radial distance so as to create a constant acoustical resistance radially. In another embodiment, the present invention is directed to a system containing both the aforesaid center cone, an outer cone with similar radial characteristics but being concave towards its center. The segments of the outer cone preferably terminate at a flexible, high sound absorption ring. The center cone fits within an orifice at the center of the outer cone.

Abstract: Acoustic speaker cones have a plurality of thin, pie-shaped segments radiating outwardly from their center with each of the segments having an arcuated cross-section. The cones are made of polycarbonate plastic and take the form of being convex towards the center for high frequency cones or of being concave towards its center for larger broad range cones. The present invention is also directed to a system containing both the aforesaid high frequency cone, and an outer broad range cone with similar radial characteristics The segments of the outer cone preferably terminate at a flexible, high sound absorption ring. The center cone fits within a central orifice at the center of the outer cone. The polycarbonate cones have a specific gravity of about 1.10 and about 1.40, having an electrical dissipation factor of about 0.05 to about 0.30 at 60 Hertz, having an electrical dissipation factor of about 1.00 to about 1.25 at 10.sup.6 Hertz, and having a thermal condutivity of at least 1.2 BTU/hr/ft.sup.2 /.degree.F.

Abstract: An electroacoustic transducer has a diaphragm body including a planar diaphragm having an outer periphery in an elongated generally elliptical shape with semicircular ends and major and minor axes, and an elastometic edge having an outer periphery of an elongated generally elliptical shape with semicircular ends and major and minor axes aligned with the major and minor axis of the diaphragm, the edge being wider along the major axis than along the minor axis and coupled at an inner periphery to the outer periphery of the diaphragm. The edge has a concave cross-section perpendicular to the diaphragm. A cylindrical voice coil bobbin is secured at one end to a central area of the diaphragm, and a voice coil is wound on the voice coil bobbin. A molded resin frame having a generally rectangular shape includes an opening conforming in shape to and receiving the diaphragm body, and is connected to and supports an outer periphery of the edge.

Abstract: The present invention provides a loudspeaker including a case having an inner wall, a front opening, and an edge surrounding the front opening. A diaphragm including a substantially planar front surface, a rear surface, and a periphery is attached to the case with flexible attachment element(s). The attaching means attaches the periphery of the diaphragm to the case in the vicinity of the edge of the front opening. A controller is attached to the case in the vicinity of a central inside portion of the case. An actuator is attached to the diaphragm in the vicinity of a central portion of the diaphragm. The controller and the actuator transform an electric signal provided to the controller into a corresponding vibratory movement of the diaphragm between a high frequency and a low frequency. The diaphragm includes a first area in the vicinity of where the actuator is attached to the diaphragm. The diaphragm also includes a second area between the first area and the periphery of the diaphragm.

Abstract: A planar diaphragm loudspeaker incorporating a planar diaphragm having multiple sound producing regions, a support frame, and one or more electromagnetic drivers coupled to the sound producing regions on the rear surface of the diaphragm. A first sound producing region is formed generally centrally on the rear surface of the diaphragm, and second and third sound producing regions are formed on opposite sides thereof. The sound producing regions comprise raised portions on the rear surface of the diaphragm which are symmetrical about both first and second orthogonal axes for balance. Cross members extend between opposite sides of the support frame so as to overlay all of the sound producing regions to selectively mount separate electromagnetic drivers for coupling to each sound producing region, as well as to mount one or more anchors extending from the cross members to the perimeters of the second and third sound producing regions in order to isolate them from the first sound producing region.

Abstract: A planar-type loudspeaker incorporating a substantially planar diaphragm constructed from a pre-expanded cellular plastic material, such as polystyrene, in which one or more balancing weights are embedded in a resilient material within recesses formed in the rear surface of the diaphragm. The resilient material enables the weights a degree of movement relative to the diaphragm, such that the weights can serve a counteractive function to help control the frequency response characteristic of the diaphragm.

Abstract: To improve loudspeakers (10) with an internal magnet system (11), it is proposed that the moving coil (21) be carrierless in configuration, and be attached to a tubular segment (20) configured concurrently when the membrane (13) is produced.

Abstract: An apparatus for generating acoustic pressure pulses in an acoustic medium has a membrane that can be driven which adjoins the acoustic medium and which is driven in an impact-producing manner. The membrane is mechanically pre-stressed so that it returns into its initial position after a pressure pulse is generated.

Abstract: A loudspeaker diaphragm has a surround comprising vibratile material extending between an inner circle and an outer circle. The material has a thin compliant roll near the outer circle and an outer circular bead inside of and near the thin compliant roll. An inner ridge having both radial and tangential components extends between the inner circle and the outer circular bead. The width of the outer circular bead and the inner ridge is significantly less than the diameter of the outer circle. The attachment area between the cone body and the surround covers a substantial area of the cone body.

Abstract: A speaker has an edge member which includes a plurality of peripheral pieces and a plurality of connecting portions for connecting neighboring ones of the pieces. The neighboring ones of the pieces have cross-sectional shapes symmetric with respect to each other in an axial direction of the edge member. Each of the connecting portions has a cross-sectional shape that changes gradually and continuously. A diaphragm which is secured to an inner periphery or an outer periphery of the edge member, and a frame is secured to an outer periphery or an inner periphery of the edge member.

Abstract: A sonic transducer (10) includes an elongated diaphragm (12) secured to a base (14) by a clamping member (16). The shapes of the surfaces (26, 30) by which the base (14) and clamping element (16) engage the diaphragm (12) are different at the end regions (28) from what they are in the side regions (32). The result is a more-rigid clamping at the ends than at the sides, which causes the lengthwise and widthwise stiffnesses of the diaphragm to be more nearly equal and thus the sound production from various regions of the diaphragm to be more nearly in phase than they would be if the clamping were uniform.

Abstract: A flexural mode acoustic transducer system for use in pulse-echo ranging systems has a radiating plate of which even-numbered antinodal zones, counting from a drive connection to a driving element at the center of the plate, are formed with rings of apertures to reduce the radiating areas of those zones, thus reducing cancellation in the far field, and improving the matching of the device to the atmosphere into which the plate is radiating. The plate is backed by a sound deadening layer on a flange of a transducer housing, from which it is separated by a foil which is non-adherent to the plate, and is preferably covered by an acoustically transparent fabric having a pore size small enough to exclude damaging particulates.

Abstract: An improved audio transducer includes a diaphragm having a pair of cylindrically-shaped webs that provide greater bandwidth, reduced distortion and greater horizontal dispersion of sound. The audio output of the transducer is further improved by forming the diaphragm of a polyvinyl fluoride film. Other improvements include the use of damping pads to damp internal sound waves and damping strips on the diaphragm to minimize distortion at the resonant frequency of the transducer. In one alternative embodiment a laminated diaphragm is used to damp resonance in the high-frequency end of the transducer operating range.

Abstract: This is a highly directional floor microphone. A pair of hinged panels rest upon the floor. A compliance may be used to acoustically seal the panels to the floor. At the apex of the floor and hinge is a transducer. The hinged panels are trapezoidal in shape and the hinge is acoustically opaque. The floor increases the directivity 6 dB. The panels increase the directivity by 12 dB. Tapering the panels in a trapezoidal shape increases the directivity by 2 dB. The total increase in directivity is 20 dB, allowing a working distance of ten times that of an omni-directional microphone. The folding nature allows easy storage and carriage.

Abstract: An acoustic source apparatus has a loudspeaker enclosed within a substantly pressure resistant and water tight enclosure. Acoustic energy from the loudspeaker emanates through an opening in the enclosure. This opening is covered by a resilient diaphragm that transmits the acoustic energy to an aqueous medium. A net constrains the diaphragm to a preselected size and shape. The net further impedes overexpansion of the diaphragm and restrains the diaphragm from migrating due to buoyancy. Additonally, the net stiffens and strengthens the diaphragm, to thereby increase the resonant frequency, impedance and quality factor of the transducer system and decrease the transmission bandwidth of the system. Constraining the transducer diaphragm with the net makes higher transducer source levels possible.

Abstract: The positive characteristics of loudspeaker diaphragms are improved by the use of a thermoplastic polyurethane sheet with a thickness of 0.06 to 0.8 mm at least for the moving part (1).

Abstract: An improved flat sound transducer including a planar diaphragm having at least one region suited for reproduction of low frequencies and one region suited for reproduction of high frequencies wherein the frame of the flat sound transducer is used to sandwich a foam strip between the frame and the diaphragm in order to dampen low frequency vibrations and substantially isolate the high frequency region from the large amplitude low frequency vibrations while still allowing high frequency vibrations to emanate from the entire sound transducer diaphragm. The dampening strip may used with either a metallic frame or with a unitary plastic frame. A high frequency enhancement coating may be used to increase the frequency response in the high frequency region of the diaphragm.

Abstract: A speaker cone plate is provided with an inorganic surfacial hard layer formed at least on a face of a metal substrate and is subjected to a reinforcing treatment by hot isostatic pressing, wherein the surfacial hard layer may be composed of a carbide, an oxide, a borie or a phosphide or may be formed by plasma thermal spraying of an inorganic substance containing silicon nitride whiskers or silicon carbide whiskers.

Abstract: An improved audio transducer includes a diaphragm having a pair of cylindrically-shaped webs that provide greater bandwidth, reduced distortion and greater horizontal dispersion of sound. The audio output of the transducer is further improved by forming the diaphragm of a polyvinyl fluoride film. Other improvements include the use of damping pads to damp internal sound waves and damping strips on the diaphragm to minimize distortion at the resonant frequency of the transducer.

Abstract: A speaker which is thin but which is capable of providing high-fidelity reproduction and ensuring a suitable level of sound pressure even when it is brought close to a wall. A closed chamber is formed behind one part of a diaphragm mounted in an enclosure, and an open chamber is formed behind another part of the diaphragm. At least one voice coil drive unit is connected to the diaphragm. The phase difference between sounds radiated from the front and rear surfaces of the diaphragm is increased as large as possible by using an acoustic duct for the sound radiated through the open chamber, thereby minimizing cancellation of sounds and improving the sound pressure level.

Abstract: The present invention is directed to an improved acoustic speaker having a cone located about a transducer wherein the cone has a plurality a thin, pie-shaped segments radiating outwardly from the transducer with each of the segments having an accuated cross-section, thereby creating a concave side and a convex side. The segments are highly concave at the transducer and less concave with increasing radial distance from the transducer. The segments are made from a metal foil and the width of the segments may increase lineraly with radial distance so as to create a constant acoustical resistance radially. The segments preferably terminate at a flexible, high sound absorption ring.

Abstract: An electromagnetic transducer is disclosed wherein separate elongated strips of magnetic material are secured on both sides of a plane containing a flat flexible insulating thin-film diaphragm. Conductors attached to the diaphram extend primarily parallel to the magnetic strips and cause movement of the diaphram when excited electrically. The conductors can also deliver current induced by diaphram movement within the field. The magnetic strips are fastened to a frame that clamps the perimeter of the diaphram. The sub-assemblies containing the magnetic strips provide maximum available area for the propagation of acoustic waves to and from the environment and provide increased flux density.

Abstract: A speaker system includes a thin plate type vibrating element mounted in, and brought into contact with, a balloon formed of a synthetic rubber or resin film. The balloon comprises a balloon member formed of a flexible film such as a vinyl chloride resin or synthetic rubber film and having therein a pocket, in which an inner film forming the pocket has an area somewhat larger than that surrounded with a laminating line on an outer film forming the pocket, whereby the inner film is brought in pressure contact or engagement with the outer film, when the balloon assembly is inflated.

Abstract: A dome-shaped acoustic motor diaphragm having a core of aluminum foil in the form of a spider web configuration resulting in the dome shape, the diaphragm being in the form of an annular semi-dome outer diaphragm part and a dome-shaped cylindrical inner diaphragm part. The spider web core also enables a wide variety of diaphragm shapes to be possible. A voice coil bobbin is passed through a lower diaphragm layer and unto the underside of an upper diaphram layer via the core which more or less is the greatest height of the same core in the region of the outer diaphragm part, thereby resulting in a highly effective bonding strength between these parts. Damping is accomplished by means of a cylindrical bellows having a height representing the maximum excursion distance of the movable parts. A bobbin guide positioned within the bobbin and bonded to the inner face of the lower magnetic pole piece prevents the bobbin and voice coil in the annular air gap from contacting the pole pieces.

Abstract: A planar loudspeaker system having an elongated and substantially planar enclosure, configured to house tweeter, midrange, and a pair of upper and lower woofer diaphragms in its median, longitudinal section. A pair of woofer labyrinths, acting as quarter-wave transmission lines, extends throughout the remainder of the enclosure's volume. The labyrinths vent the substantially in-phase backwaves forwardly, toward the listener, through a pair of shared ports in the mid-frontal region of the enclosure. An electro-magnetic drive unit, employing bar magnets, pole pieces and thin encapsulated moving coils, all of elongated and symmetrical configuration, is also disclosed. Three versions of the drive unit are shown, each being adapted to provide a distributive driving force to the planar diaphragms of the loudspeaker.

Abstract: A sound projection system for use in diffusing sound of a frequency ranging from 160 Hz up to 5 KHz over a relatively long distance with a substantially constant distribution of the sound over a wide diffusion angle, whereby the quality and intensity of the sound transmitted by the system remain substantially constant for a listener even if this person is substantially offset from the general direction and orientation of the projection system. The system which is advantageously compact in size, comprises a cabinet defining an enclosure in which a loudspeaker is mounted. An acoustic channel of rectangular cross-section is connected to the cabinet in alignment with the loudspeaker.

Abstract: A magnetic speaker equipped with a flat diaphragm comprising a straight-grain wood plate or a cross-grain wood plate, for instance, made of Sitka spruce having the specific gravity range from 0.25 to 0.8, presenting excellent acoustic properties, especially, suitable for low to medium frequency speakers. The flat diaphragm is treated to chemically modify hydroxyl groups contained in the wooden component. Modification may be by esterification, etherification, acetilation, formalinization, or the like to enhance acoustical characteristics.

Abstract: An acoustic diaphragm is made of metallic sheet material forming a raised pattern of the material and unraised sectors of the material. The diaphragm is of the dome-shaped variety. The raised pattern incorporates sets of raised strip elements. There is a set of such elements extending radially from the vicinity of the apex. There is a set extending along areas of the sheet material between the radially extending elements, this second set including pairs of strip elements which intersect one another along such areas. There is also a set of circumferentially extending raised strip elements. The form of the radially extending elements changes along their lengths; for example, they rise to levels which vary along their lengths.

Abstract: The method of making the diaphragm includes pressing on the front face of a film at spaced apart areas to deform it progressively into a series of closely-spaced generally U-shaped projections. A manufacturing device presses the sides of the projections inwardly to rigidify them. The transducer magnet assembly includes a series of elongated magnet pole-piece strips which confine magnets and are arranged in parallel spaced-apart rows with the ends thereof fitted into transverse elongated grooves extending within a pair of elongated cross-piece end members. The driver is fixed together in a precise manner by flowing an adhesive material into the grooves, and then by allowing such material to harden.