Abstract: A loudspeaker driver surround 2 comprises a flexible, generally annular element having a central axis 8 along which in use a diaphragm is driven, an outer edge 6 for fitment to an enclosure and an inner edge 4 for fitment to the diaphragm, with a roll surface which extends between the edges and which projects in the direction of the axis, wherein the roll surface has a shape formed by a plurality of axial corrugations 10 extending generally radially with respect to the annular element between the outer and inner edges thereof, the corrugations being shaped and configured such that the roll surface is non-axisymmetric about the axis, and the arrangement being such that cross-sections of the roll surface which extend radially with respect to the annular element between the outer and inner edges thereof have a substantially constant length at all circumferential positions around the annular element and so that the shape of the said cross-section varies continuously between circumferential positions around the an

Abstract: The present invention relates to a loudspeaker which can be arranged to minimise its overall depth while also increasing the breakup frequency and reducing potential rocking vibrations.

Abstract: An acoustic insert for lining a loudspeaker reflex port, the insert comprising an elongate hollow tube formed of a flexible material, having an outer wall sized and configured to seat within the port and an inner wall extending in the elongate direction, the inner wall having a circumference which varies along the length of the insert, When inserted in a port, the insert alters the port resonance so as to vary the acoustic perfoi mance of the loudspeaker.

Abstract: A phase plug for a loudspeaker having a driven diaphragm, wherein at least a portion of the surface of the phase plug disposed in use adjacent the diaphragm is generally annular in two orthogonal directions and has an axis in a third orthogonal direction, and wherein at least a portion of the said annular surface is shaped such that as successive radial cross-sections through the annular surface are generated by rotating a plane about the axis, the cross-sectional shape of the surface of the phase plug varies periodically as the angle of rotation increases.

Abstract: A diaphragm for a loudspeaker, wherein the diaphragm is formed generally in a closed loop around a central void, the loop lying in a plane, the diaphragm having an axis in a direction orthogonal to the plane along which axis the diaphragm is arranged to be driven in use, the diaphragm having inner and outer circumferential edges which are adapted, in use, to be fixed in position, wherein a substantial portion of the diaphragm between the inner and outer edges is shaped in the direction of the said axis so as to protrude from the general plane of the diaphragm in either or both directions along the axis, and wherein said shaped portion when viewed along the direction of the axis comprises at least one series of curves extending radially across substantially all of the driven area of the diaphragm.

Abstract: A ring-shaped surround for a loudspeaker is disclosed, in the form of a membrane formed in a shape that, when relaxed (i.e. when not being driven), has a cross sectional shape with a first portion extending in a radial direction for a first distance, a second portion extending in an axial direction for a second distance, and a third portion extending in a radial direction for a third distance, the first and second portions being connected by a first flexible join, and the second and third portions being connected by a second flexible join, the first join having a first radius of curvature that is shorter than at least one of said first and second distances, the second join having a second radius of curvature that is shorter than at least one of said second and third distances. Thus, the surround has a Z-shape, with a first radially extending portion, and a relatively sharp bend leading to an axially-extending portion.

Abstract: The present invention provides a loudspeaker with at least two diaphragm assemblies, in which the reactive forces acting on the magnets in each assembly cancel. By linking the two magnets together via a non-rigid material, resonance in the drive assemblies is highly damped and corresponding distortion of the loudspeaker output is reduced.

Abstract: The present invention provides a loudspeaker with a port tube having an acoustic leakage path through a motile part thereof. In this way, excess energy caused by longitudinal resonance at higher frequencies is radiated transversely through the port tube walls rather than contributing to the output of the loudspeaker itself.

Abstract: A loudspeaker radiating diaphragm can be stiffened to help increase the breakup frequency to above the working frequency range of the driver concerned, by forming it of a molded part and an attached formed part. The molded part is a radiating surface with stiffening ribs. The formed part is a thin surface of high modulus material, attached to the rear of the ribs. The overall structure can have significantly higher stiffness than either of the two parts. This helps in designing a loudspeaker driver that does not breakup within its working frequency range.

Abstract: A loudspeaker is disclosed, comprising a driven body and a suspension for providing a restoring force to the driven body, the suspension having a cup geometry wherein its attachment point on the fixed portion of the loudspeaker is displaced along the axis of motion relative to its attachment point on the driven body and comprising a first concentric region that is extendible to allow reciprocating axial movement of the driven body, a second concentric region which extends transversely from the first region toward one of the attachment points, and a circumferential member affixed to the suspension at a location between the first and second concentric regions, the circumferential member being relatively stiff compared to the material forming the first and second concentric regions.

Abstract: A loudspeaker comprising an acoustically radiating diaphragm comprising a generally frustoconical membrane having a narrow neck end and a wide mouth end, stiffening formations for stiffening the radiating membrane and an interface region by which the diaphragm is adapted to be driven; and a transducer comprising a voice coil mounted to drive the diaphragm via its interface region; wherein the interface region is located at the node of the first mode of vibration of the diaphragm.

Abstract: The present invention provides a loudspeaker with a port tube having an acoustic leakage path through a motile part thereof. In this way, excess energy caused by longitudinal resonance at higher frequencies is radiated transversely through the port tube walls rather than contributing to the output of the loudspeaker itself.

Abstract: A loudspeaker comprising a horn waveguide having a throat and a waveguide surface; an acoustic radiator assembly, located at the throat of the waveguide, comprising a diaphragm having a rigid acoustically radiating surface shaped as a section from a toroidal surface for generating acoustic wavefronts, the waveguide surface being adapted to match the shape of the wavefronts coming from the assembly.

Abstract: A loudspeaker radiating diaphragm can be stiffened to help increase the breakup frequency to above the working frequency range of the driver concerned, by forming it of a moulded part and an attached formed part. The moulded part is a radiating surface with stiffening ribs. The formed part is a thin surface of high modulus material, attached to the rear of the ribs. The overall structure can have significantly higher stiffness than either of the two parts. This helps in designing a loudspeaker driver that does not breakup within its working frequency range.

Abstract: A loudspeaker that can be bi-wired or not according to a user's preference comprises a case in which is provided a plurality of audio drivers supplied by a respective plurality of audio networks, the networks being supplied (in turn) by a respective plurality of input terminal pairs, further comprising at least one switch bridging the terminals of different pairs, and adapted to selectively connect the terminals to each other.

Abstract: A loudspeaker comprising an acoustically radiating diaphragm comprising a generally frustoconical membrane having a narrow neck end and a wide mouth end, stiffening formations for stiffening the radiating membrane and an interface region by which the diaphragm is adapted to be driven; and a transducer comprising a voice coil mounted to drive the diaphragm via its interface region; wherein the interface region is located at the node of the first mode of vibration of the diaphragm.

Abstract: A ring-shaped surround for a loudspeaker is disclosed, in the form of a membrane formed in a shape that, when relaxed (i.e. when not being driven), has a cross sectional shape with a first portion extending in a radial direction for a first distance, a second portion extending in an axial direction for a second distance, and a third portion extending in a radial direction for a third distance, the first and second portions being connected by a first flexible join, and the second and third portions being connected by a second flexible join, the first join having a first radius of curvature that is shorter than at least one of said first and second distances, the second join having a second radius of curvature that is shorter than at least one of said second and third distances. Thus, the surround has a Z-shape, with a first radially extending portion, and a relatively sharp bend leading to an axially-extending portion.

Abstract: A compound loudspeaker comprises an acoustically radiating first diaphragm and an acoustically radiating second diaphragm. The first and second diaphragms are substantially coaxial and at least part of the second diaphragm is situated radially outwards of the first diaphragm. There is a gap situated between the first and second diaphragms, and a seal is provided in the gap, thereby preventing or hindering the passage of air through the gap. By providing the seal, the invention solves the problem of audible turbulent airflow through the gap.

Abstract: A phase plug comprises a body having an input side for receiving acoustic waves and an output side for transmitting acoustic waves, the body including a plurality of channels extending from the input side to the output side for propagating acoustic waves through the body. The input side comprises an input surface which includes a plurality of openings constituting entrances for the channels, the input surface being substantially part of a sphere or an ellipsoid in shape. The areas of the openings vary with radial position on the input surface, the radial position being measured in a direction extending perpendicularly from a central axis extending through the input surface. The variation in the areas is a function of the cosine of an angle subtended at the centre of the sphere or a focus of the ellipsoid between the central axis and the radial position.

Abstract: A phase plug comprises a body having an input side for receiving acoustic waves and an output side for transmitting acoustic waves, the body including a plurality of channels extending from the input side to the output side for propagating acoustic waves through the body. The input side comprises an input surface which includes a plurality of slots constituting entrances for the channels, each slot being arranged in a substantially radial orientation on the input surface about a central axis extending through the input surface. Substantially the entire input surface situated between the slots is concave and substantially part of a sphere or an ellipsoid in shape.