Abstract: The present invention relates to a motor for an electrodynamic loudspeaker, comprising a magnetic circuit assembly arranged about a motor axis. The magnetic circuit assembly comprises: an outer magnet, a magnetically permeable top plate, a magnetically permeable bottom plate, a center pole piece and an air gap for receipt of a voice coil. The air gap is formed by an inner axially extending wall of the magnetically permeable top plate facing an axially extending peripheral wall section of the center pole piece to define a width, a bottom, a top and height of the air gap. The magnetic circuit assembly additionally comprises outwardly projecting magnetically permeable member arranged above the top of the air gap. The center pole piece comprises a magnetic member extending axially from at least the bottom of the air gap to a magnetically permeable bottom member or to the magnetically permeable bottom plate.

Abstract: A speaker device including a magnet formed in a ring shape; a yoke having a center pole portion inserted in the center of the magnet; a plate formed in a ring shape and arranged on an outer circumferential surface of the center pole portion of the yoke while being attached to the magnet; a coil bobbin formed in a cylindrical shape and movable in the axial direction of the center pole portion while being partially fitted on the center pole portion of the yoke; a voice coil wrapped around the outer circumferential surface of the coil bobbin, at least part of the voice coil being arranged in a magnetic gap formed between the plate and the center pole portion of the yoke; a diaphragm having its inner circumferential portion connected to the coil bobbin; and a magnetic fluid filled in the magnetic gap.

Abstract: An electromagnetic drive unit for a loudspeaker of the type where an air gap is arranged in a magnet system such that magnetic flux lines are substantially linear across the air gap, and that a voice coil is arranged in said air gap, wherein the magnet system comprises a central yoke separated by said air gap from a ring-shaped magnet system, which magnet system at least comprises a bottom plate connected to said central yoke, and a magnet and a top plate, characterized in that at least a section of the central yoke corresponding to the extent of the air gap and at least a corresponding section of the top plate is made from a soft magnetic composite material.

Abstract: A magnetic motor system for driving a loudspeaker voice coil. The system has first and second parts that define a volume for receiving a voice coil. The first and second parts each have a respective permanent magnet with first and second sidewalls that extend in a direction away from the volume. The first sidewall slopes in a direction towards the second sidewall as the sidewalls extend away from the volume. The first and second parts further have respective guide members for channelling lines of magnetic flux in a return path between the permanent magnets.

Abstract: The present invention is to provide a structure of speaker driver, it comprising a base, a drum paper, a yoke, a sound coil and a magnetic unit. The base includes an upper combining portion and a lower combining portion. The drum paper is configured to the upper combining portion. The yoke is configured to the lower combining portion. The sound coil is configured to an underside of drum paper surroundingly. The magnetic unit has a magnet and a front plate, the magnetic unit is configured to above the yoke. Wherein an internal ring surface of yoke has a surface of first poly-magnet and a surface of second poly-magnet, the surface of first poly-magnet is closer to center of yoke than the internal ring surface, the surface of second poly-magnet rises along with the internal of yoke, a bottom of yoke also rises to correspond to the surface of second poly-magnet; an external ring surface of front piece is more distant from center of front piece than an external ring surface of magnet.

Abstract: An electro-dynamic loudspeaker transducer's motor structure includes a magnetic circuit having a pole with minimal reluctance that allows the use of larger magnets and thicker front plates, thus generating higher flux density in the voice coil gap. The lower reluctance is achieved by increasing the pole piece's outside diameter at all points outside of the voice coil gap and the area swept out by the voice coil at maximal inward excursion. Increasing the pole's diameter over a substantial amount of the pole's distally projecting length (but not extending into the magnetic gap), provides an increased cross sectional area and a reduced magnetic circuit reluctance.

Abstract: This invention relates to acoustic transducers with stationary and moving coils, and methods for operating the acoustic transducers. Time varying signals are applied to the moving and stationary coils to control the movement of a diaphragm, which produces sound. The time varying signal applied to the moving coil corresponds to at least a processed version of an input audio signal and is updated based on, at least, a version of the time varying signal applied to the stationary coil. Some embodiments include updating the processed version of the input audio signal in response to a magnetic flux value corresponding to the time-varying signal applied to the stationary coil. Some embodiments include updating the time-varying signal applied to the moving coil in response to a feedback signal.

Abstract: A loudspeaker includes a woofer having a first permanent magnet disposed substantially within a center pole having an associated magnetic polarity and generating a flux path through an air gap, a voice coil at least partially positioned in the air gap and having an inside diameter larger than an outside diameter of the first permanent magnet, a frame, a spider connecting the voice coil to the frame, and a diaphragm connected between the voice coil and the frame. A tweeter is generally coaxially positioned relative to the woofer and includes a second permanent magnet. A third permanent magnet is coaxially positioned between the woofer and the tweeter. A non-magnetic structure may encompass the third permanent magnet.

Abstract: A speaker device including a magnet formed in a ring shape; a yoke having a center pole portion inserted in the center of the magnet; a plate formed in a ring shape and arranged on the outer circumferential surface of the center pole portion of the yoke while being attached to the magnet; a coil bobbin formed in a cylindrical shape and movable in the axial direction of the center pole portion while being partially fitted on the center pole portion of the yoke; a voice coil wrapped around the outer circumferential surface of the coil bobbin, at least part of the voice coil being arranged in a magnetic gap formed between the plate and the center pole portion of the yoke; a diaphragm having its inner circumferential portion connected to the coil bobbin, the diaphragm being vibrated as the coil bobbin moves; and a magnetic fluid filled in the magnetic gap.

Abstract: An apparatus related to a magnetic circuit design is disclosed. The apparatus includes a magnetic assembly and an electrically-conductive mobile member. The magnetic assembly includes an inner magnet, an outer magnet, an inner cap, an outer cap and a washer. The magnetic assembly is configured to produce a magnetic field having a zone of operation between the inner cap and the outer cap. The zone of operation has substantially uniform magnetic field strength. The zone of operation has magnetic field directions substantially perpendicular to an ideal motion direction. The electrically-conductive mobile member is disposed in the zone of operation of the magnetic field and electrically coupled to a diaphragm of a driver. The electrically-conductive mobile member is configured to move within the zone of operation of the magnetic field in response to the magnetic field when an alternating current is passed through the electrically-conductive mobile member.

Abstract: A magnetic circuit includes a magnet, a first plate, and a yoke, and has a magnetic gap. The first plate and the yoke are joined to the magnet. The magnet includes first and second magnet parts. The second magnet part has a lower magnetic property than that of the first magnet part. Such a first magnet part is disposed in a vicinity of the magnetic gap. On the other hand, the second magnet part is disposed farther from the magnetic gap than the first magnet part. The first and second magnet parts are connected in parallel to each other. With this configuration, the second magnet part makes a small contribution to the magnetic flux density in the magnetic gap. Therefore, the magnetic property of the second magnet part may be low, and an inexpensive magnet can be used as the second magnet part.

Abstract: The present disclosure is directed to inventive methods and apparatus for a variable flux speaker subassembly for a loudspeaker. The variable flux speaker subassembly may contain at least one repositionable structure that is repositionable from at least a first position to a second position. The magnetic flux through a voice coil structure of the speaker subassembly is altered when the repositionable structure is moved from the first position to the second position.

Abstract: A balanced electromagnetic transducer, including first and second components connected together by a flexible component, at least a part of which flexes upon exposure of the transducer to energy, wherein the transducer is configured to generate a static magnetic flux that passes from the first component to the second component via the flexible component and travels across no more than two air gaps.

Abstract: Single magnet coaxial loudspeaker having two air gaps on both sides of its faces, front gap of larger diameter for low frequency voice-coil and the opposite gap accommodating compression driver voice-coil. Front voice-coil drives low frequency membrane and rear voice-coil drives high frequency diaphragm, radiating sound waves through a phasing plug to the horn input through an opening into the magnetic structure, whereas the membrane acts as horn flair. Common region geometry around bottom pole of the magnetic structure controls flux line proportions between the two gaps. The five embodiments use series or parallel, inner or outer magnetomotive flux division. These are suitable for much simpler, more reliable and better balanced coaxial loudspeakers for professional and high-end markets.

Abstract: A magnet assembly for a audio speaker provides a gap through which a voice coil assembly passes. A magnetic member, a yoke, and a pole piece form a magnetic circuit that focuses magnetic energy in the gap. A spider movably supports the voice coil assembly. The spider is coupled to one of the magnetic member or the yoke by forming the one of the magnetic member or the yoke in two parts and joining the two parts with a portion of the spider between the two parts. The spider may be formed from a thin film thermoplastic, such as polyetheretherketone (PEEK), and may be less than 10 microns thick. The portion of the spider that is between the two parts may be shaped such that a portion of the two parts are in direct contact with one another.

Abstract: A speaker includes a ring-shaped magnet, a yoke having a center pole portion inserted in the center of the magnet, and a ring-shaped plate and arranged on the outer circumferential surface of the center pole portion of the yoke and attached to the magnet. The speaker includes a cylindrically-shaped coil bobbin that is movable in the axial direction of the center pole portion and partially fitted on the center pole portion of the yoke. The speaker includes a voice coil wrapped around the outer circumferential surface of the coil bobbin, part of the voice coil being arranged in a magnetic gap, which is filled with a magnetic fluid, formed between the plate and the center pole portion of the yoke. The speaker includes a diaphragm having its inner circumferential portion connected to the coil bobbin, and that is vibrated as the coil bobbin moves.

Abstract: An acoustic transducer includes a sound-producing member at least partially disposed within the first magnetic flux gap region between the magnetic poles. The sound-producing assemblage is magnetically excited through a magnetic circuit that passes from a location outside the magnetic flux gap region to inside the magnetic flux region through an air gap. The moving member is controllably movable under the influence of at least one varying magnetic field, and its movement is constrained by a unique combination of mechanical restraints and magnetic restraints imposed upon the moving member by the interaction of a plurality of magnetic fields.

Abstract: A loudspeaker includes an outer frame with an annular magnet partially exposed from a bottom thereof; a voice coil located inside the annular magnet; a diaphragm glued to between an expanded front opening of the outer frame and the voice coil; a flexible suspension ring having an outer edge fixed to a stepped section of the outer frame and a central opening edge clearance-fitted to a middle/front portion of the annular magnet; and an inner frame having a front portion fitted around the voice coil, a rear portion located on the central opening edge of the flexible suspension ring, and legs extended between the front and rear portions to locate in front of slots formed on the annular magnet. Therefore, the loudspeaker has reduced depth and volume, increased vibration amplitude and stability, and high quality sound output.

Abstract: A magnetic circuit for a loudspeaker includes a magnet and a top plate. The magnet is made of a bonded magnet. The magnet and the top plate are configured to satisfy at least one of conditions that an inner diameter of the magnet is identical to an inner diameter of the top plate, and that an outer diameter of the magnet is identical to an outer diameter of the top plate. This configuration eliminates a wasted space inside the magnetic circuit, and protrusion of the magnet to outside, hence providing a light and efficient magnetic circuit.

Abstract: Disclosed is a multi-magnet system for speaker. The multi-magnet system includes a yoke having a bottom, a pair of main magnets separated from each other and mounted on the bottom of the yoke, respectively, a mid-magnet mounted on the bottom of the yoke and located between the pair of main magnets, and a pair of auxiliary magnets attached to two ends of the yoke. Wherein, the first main magnet together with the first auxiliary magnet and the mid-magnet defines a first magnetic gap and the second main magnet together with the second auxiliary magnet and the mid-magnet defines a second magnetic gap. By virtue of place the magnets at appropriate locations, the sensitivity of the speaker is effectively enhanced.

Abstract: An acoustic transducer includes a sound-producing member at least partially disposed within the first magnetic flux gap region between the magnetic poles, the sound-producing assemblage is magnetically excited through a magnetic circuit that passes from a location outside the magnetic flux gap region to inside the magnetic flux region through an air gap.

Abstract: A speaker includes a ring-shaped magnet, a yoke having a center pole portion inserted in the center of the magnet, and a ring-shaped plate and arranged on the outer circumferential surface of the center pole portion of the yoke and attached to the magnet. The speaker includes a cylindrically-shaped coil bobbin that is movable in the axial direction of the center pole portion and partially fitted on the center pole portion of the yoke. The speaker includes a voice coil wrapped around the outer circumferential surface of the coil bobbin, part of the voice coil being arranged in a magnetic gap, which is filled with a magnetic fluid, formed between the plate and the center pole portion of the yoke. The speaker includes a diaphragm having its inner circumferential portion connected to the coil bobbin, and that is vibrated as the coil bobbin moves.

Abstract: An example apparatus comprises a drive coil energizable by a drive signal, at least one permanent magnet, and at least one magnetic return path element for flux induced by the drive signal, the magnetic return path element, such as a balanced armature, being configured to provide a variable reluctance, so as to reduce nonlinearities in a displacement versus drive signal relationship. Modifying the reluctance versus flux properties of the magnetic return path of a transducer, e.g. the armature of a balanced armature device, allows compensation for nonlinearity arising in another part of the apparatus.

Abstract: Disclosed is a linear actuator which includes a core, a coil, a magnet assembly, and a housing. The coil that is shaped to be positioned about the core for movement along a longitudinal axis of the core. The housing is supported by core flanges and positioned about the coil and the core. The magnet assembly includes magnets of the same polarity facing the coil and shaped to be positioned inside or outside of the coil, and supported by the core or by the housing, respectively. The core includes first and second portions, each having an end face, and the first and second portions are positioned along the longitudinal axis so that the end faces oppose each other and are separated by a gap. A cavity is formed in each of the end faces along the longitudinal axis.

Abstract: A magnetic circuit includes a cylindrical yoke member having an inner circumferential surface and a collar formed at one end thereof and turned back substantially at right angles, and a plurality of permanent magnet segments of a partially circular arc in cross section. Each of the permanent magnets has an outer surface attracted magnetically to the inner circumferential surface of the cylindrical yoke member, and one end face attracted magnetically to the collar of the cylindrical yoke member. The magnetic circuit is applied to an actuator or a speaker.

Abstract: A magnet structure for use with a loudspeaker has an interlocking mechanism. The magnet structure can include a magnet, a shell pot and at least one core cap. The shell pot can contain the magnet in its hollow interior. The magnet can be a single magnet or double magnets. The core cap has two surfaces. For a single magnet, one surface of the core cap faces the magnet. For double magnets, the core cap can be vertically disposed between the two magnets. The magnet, the core cap and the shell pot can interlock with one another such that a position of the magnet relative to the core cap and the shell pot can be rigidly preserved. The magnet can be configured to be, for example, overlapped, inserted, staked and/or engaged with at least one of the shell pot or the core cap.

Abstract: The present disclosure is directed to inventive methods and apparatus for a variable flux speaker subassembly for a loudspeaker. The variable flux speaker subassembly may contain at least one repositionable structure that is repositionable from at least a first position to a second position. The magnetic flux through a voice coil structure of the speaker subassembly is altered when the repositionable structure is moved from the first position to the second position.

Abstract: The present invention relates to a dynamic type unit with a multiple magnetic field system, and more particularly, to a dynamic type unit including a magnet, a diaphragm and a moving coil such as a microphone or a speaker, wherein an auxiliary magnet is mounted around a main magnetic field formed by the magnet so as to form an auxiliary magnetic field to thereby correct a waveform of each individual distorted frequency generated from the microphone or the speaker, which results in realization of the best sound whose quality is closest to that of an original sound.

Abstract: An audio speaker with at least two electric coils on opposite sides of at least one ferro-magnetic plate, the coils and plate forming a radial electro-magnet. A radial electro-magnet can offer many advantages in stereo loudspeakers. The coils are electrically driven in opposite directions. Multiple sets of two coils and intervening ferro-magnetic plate may be provided, adjacent sets being separated by a non-magnetic plate.

Abstract: This invention relates to acoustic drivers with stationary and moving coils. Time varying signals are applied to the moving and stationary coils to control the movement of a diaphragm, which produces audible sound. The time varying signals correspond to an input audio signal such that the sound corresponds to the input audio signal. Some of the described embodiments include multiple moving coils, multiple stationary coils or both. Some embodiments include feedback for adjusting one or more of the signals based on a characteristic of the acoustic driver. Various compensation and other features of the invention are also described in relation to various embodiments.

Abstract: Disclosed is a free air magnetic circuit and speaker in which no pole piece is used. A magnet layer is located between a top plate and a back plate with a gap defined essentially in the center thereof. Into the gap, a wire coil attached to a diaphragm may be inserted. A magnet flux passes between the top and back plates. In some embodiments, the interior edge of each of the metal plates tapers toward the gap, and the magnet layer extends past the peripheral edge of each of the metal plates so as to discourage magnetic flux between the metal layers at the peripheral edge.

Abstract: An electrodynamic transducer includes a frame and contains at least one electric coil which is placed in a static magnetic field and which can move about a rest position in a vertical free space. The coil(s) is wound around and fixed to a mandrel and a return member is used to return the coil-bearing mandrel to the rest position in the absence of an external bias, the straight cylinder defining an inner volume and an outer volume. The magnetic field is produced by outer and inner magnetic structures which each comprise at least one fixed permanent magnet in the form of a ring. The motor does not contain any ferromagnetic or magnetic part between the outer volume and the inner volume. At least the part of the frame that is used to fix the magnets is made from a non-ferromagnetic and non-magnetic material.

Abstract: Disclosed is a magnetic circuit for a speaker. The magnetic circuit includes a yoke defining a bottom and a sidewall extending perpendicularly from the bottom, a magnet mounted on the bottom of the yoke, a pole plate mounted on a top of the magnet. The magnet includes a wider portion mounted on the bottom of the yoke and a narrower portion carrying the pole plate.

Abstract: A magnetic circuit for a speaker device includes a yoke having a pole piece main body formed into a cylindrical shape or a hollow cylindrical column shape, and a flange part provided on an outer side thereof, a magnet arranged on the flange part, a plate arranged on the magnet, and an annular T-shape forming member arranged on the pole piece main body. A magnetic gap is formed between an inner peripheral wall of the plate and an outer peripheral wall of the T-shape forming member. A configuration formed by combining the T-shape forming member and the pole piece main body forms a T-shaped pole piece.

Abstract: A magnet structure for use with a loudspeaker has an interlocking mechanism. The magnet structure can include a magnet, a shell pot and at least one core cap. The shell pot can contain the magnet in its hollow interior. The magnet can be a single magnet or double magnets. The core cap has two surfaces. For a single magnet, one surface of the core cap faces the magnet. For double magnets, the core cap can be vertically disposed between the two magnets. The magnet, the core cap and the shell pot can interlock with one another such that a position of the magnet relative to the core cap and the shell pot can be rigidly preserved. The magnet can be configured to be, for example, overlapped, inserted, staked and/or engaged with at least one of the shell pot or the core cap.

Abstract: A ribbonned microphone assembly, for adjustable sound receiving capabilities, including a transducer having a surrounding flux frame for positioning at least two magnets adjacent a suspended ribbon between the magnets. An array of receiving apertures is arranged in the flux frame. At least one curved return ring positioned in the receiving apertures to create a return path for magnetic flux in the transducer.

Abstract: An electrodynamic electroacoustic transducer comprises: a first magnetic pole; a second magnetic pole that forms a magnetic gap between itself and the first magnetic pole and is arranged in a space excluding spaces in upper and lower face directions of the first magnetic pole; a yoke; a diaphragm; and a voice coil. The yoke magnetically couples one magnetic pole face of the first magnetic pole with one magnetic pole face of the second magnetic pole so as to support them. The diaphragm is arranged in a space in an upper face direction of the first magnetic pole and in a space in a lower face direction of the second magnetic pole, while its outer periphery is supported by the yoke. The voice coil is arranged in the magnetic gap and adhered to the diaphragm. At least one of the first magnetic pole part and the second magnetic pole part includes a magnet.

Abstract: Provided herein is a voice-coil motor that includes a magnetic field having at least two displaced regions of higher intensity separated by a region of lesser intensity and a counter-coil disposed within the region of lesser intensity.

Abstract: An audio speaker has a driver unit having a support frame with a central portion forming a magnetic structure defining an annular gap around a central magnetic post, a vibration system having a diaphragm and a voice coil, the voice coil is attached to one side of the diaphragm where the vibration system is fixed to the support frame and where the voice coil is movably mounted in the annular gap, and a magnetic fluid disposed in the annular gap only in a space between one side of the voice coil and a surface of the annular gap having a higher magnetic flux density.

Abstract: An electrodynamic loudspeaker 1 includes a magnetic circuit 10 and a vibrator 20. The magnetic circuit 10 includes a magnet 11 and poles 12 and 13 adhering to the magnet 11. The vibrator 20 includes a coil bobbin 21 and voice coils 22 and 23 wound around and fixed to a portion of the coil bobbin 21 facing the poles 12 and 13. A magnetic member 30 is fixed to the coil bobbin 21 of the vibrator 20 at a position spaced apart from the voice coils 22 and 23. The magnetic member 30 is fixed at a position on the coil bobbin 21 so as to extend over an area facing the magnet 11 of the magnetic circuit 10.

Abstract: Provided herein is a voice-coil motor that includes a magnetic field having at least two displaced regions of higher intensity separated by a region of lesser intensity and a counter-coil disposed within the region of lesser intensity.

Abstract: A speaker apparatus includes at least one of an inner flux applicator and an outer flux applicator includes an annular first member and an annular second member. The first member having a first surface that faces toward the magnetic gap, the first member satisfying L1>W1 where L1 is a length of the first surface in a direction parallel to the central axis and W1 is a width of the first member in a direction orthogonal to a central axis. The second member is magnetically coupled with the first member and arranged on an outer side of the first member, the second member satisfying W2>L2 where W2 is a width of the second member in a direction orthogonal to a central axis and L2 is a length of the second surface in a direction parallel to the central axis, and L1>L2.

Abstract: Improved loudspeakers, systems and components are adapted to interconnect with many forms of communication media. In one embodiment, a speaker is mountable within a receptacle. The speaker includes a magnetic driver and a diaphragm mounted to a frame. The frame includes a mounting member extending from a surface of the frame behind the flange plane. The mounting member is engagable in a notch formed in the receptacle for securing the speaker within the receptacle. In another embodiment, a low-profile loudspeaker has a front-mounted magnetic driver disposed within a cone-shaped acoustic diaphragm. The magnetic driver includes a first rare earth magnet centrally disposed within an electromagnetic shielding material. In another embodiment, a low-profile, two-way loudspeaker includes a cone-shaped diaphragm and a dome-shaped (tweeter) diaphragm. A front-mounted magnetic driver comprises first and second rare earth magnets each centrally disposed within electromagnetic shielding material.

Abstract: An electromagnetic transducer such as an audio speaker having at least one of the soft magnetic components of its motor assembly constructed as a laminated structure of electrically insulated magnetically conductive sections. Eddy currents, which would have been induced in a monolithic component in response to an electrical signal applied to the voice coil, are prevented or significantly reduced by the electrical insulation material between the sections of the laminated component. The transducer produces less heat, is less susceptible to flux modulation, and has increased power handling and reduced distortion.

Abstract: An acoustic driver has a voice coil in which adjacent turns of the coil are spaced apart. The driver is placed at one end of a foam-lined, elongated structure, such as a tube. An opposing end of the structure is, in one embodiment, enclosed by a wall that is connected to the structure by a suspension so that it moves in sympathy with the driver. In another embodiment, the structure cooperates with the acoustic driver to form one or more restrictive passageways confined around the driver's motor and an inner surface of the structure. The passageway(s) couple a volume of air in the structure to the exterior of the structure in a manner that reduces the transmission of acoustic energy without creating alternating pressure within the structure that interferes with the movement of the voice coil's diaphragm, at its maximum points of excursion.

Abstract: A speaker includes a magnet, a yoke, and a coil. A surface of the magnet opposed to the yoke includes a first magnetized surface at one side in the moving direction of the coil and a second magnetized surface at the other side in the moving direction of the coil. The two magnetized surfaces have the same magnetic polarity. A central surface between the first magnetized surface and the second magnetized surface is not magnetized or is magnetized more weakly than the first magnetized surface and the second magnetized surface. The single magnet of this structure forms the same magnetic force distribution as two separate magnets so that the speaker provides a superior linearity of driving force of the coil.

Abstract: The present invention relates to a low-inductance electromagnetic drive without driving magnetic flux circuit, which comprises a magnetic pole, a drive coil, an upper magnetic inductive board, a permanent magnet and a lower magnetic-inductive board. The magnetic pole is integrated with the lower magnetic-inductive board, and the permanent magnet is located between the upper magnetic-inductive board 4 and lower magnetic-inductive board 6. The drive coil is wrapped around the magnetic pole and is movable in the axial direction. The electromagnetic drive further comprises the fastening coil, and the fastening coil is fastened to a certain proper place of the magnetic flux circuit of the drive coil. Furthermore, the fastening coil is connected with the drive coil in opposite phase.

Abstract: A core cap or top plate for use with loudspeakers that includes offset adhesive control grooves on the opposite faces of the disk-like core cap is disclosed. The grooves are offset from one another by a distance that makes the smallest dimension between any feature of the grooves about the same as the nominal thickness of the core cap. The core cap increases the magnetic flux capacity over prior art core cap designs, while maintaining features advantageous to error-proof the orientation of the core cap in the loudspeaker.

Abstract: An electroacoustic transducer comprising a magnetic circuit of a magnetically conductive material with a pair of opposed surfaces defining a gap therebetween, the magnetic circuit comprising a magnet inducing a magnetic field in the gap, the magnet having a surface constituting one of the opposed surfaces. The magnetic circuit further comprises a diaphragm and a coil having electrically conducting paths secured to the diaphragm. The coil has portions of its paths situated in the gap.

Abstract: An electromechanical transducer comprising at least one transducer element which has a multilayer structure comprising at least two layers such that the transducer element is capable of changing its thickness. The transducer element allows air to flow inside the transducer element in the direction of thickness thereof and inside and out of the transducer element through at least one surface of the transducer element in the direction of thickness of the transducer element. The transducer element can be used e.g. for transforming energy from mechanical energy into electric energy and/or vice versa.