Gp Acoustics (uk) Limited

Kh Technology Corporation

Gp Acoustics International Limited

Mark Alexander Dodd

Jack Anthony Oclee-Brown

Christopher Spear

Julia Davidson

A method of designing an acoustic waveguide in which acoustic waves travelling along the waveguide are treated as exhibiting single parameter behaviour, and in which the waveguide provides a boundary confining the acoustic waves as they travel along the wave propagation path and has two substantially parallel, primary surfaces spaced apart a distance less than a wavelength of a high frequency acoustic wave. The primary surfaces may be planar, curved, or a combination of planar portions and curved portions.

Acoustic waveguides

Sound emanating from the high-frequency diaphragm of a coaxial speaker will diffract into the annular gap between the tweeter unit and the midrange cone. This results in response irregularities. We therefore disclose a loudspeaker, comprising first and second drivers located substantially coaxially with the first driver located centrally and the second driver located concentrically around the first driver, the loudspeaker being bounded at its radially outer side for at least part of its extent by the voice coil former of the second driver and including a spacing between the outermost extent of the first driver and the innermost extent of the second driver thus defining an annular space, the annular space containing a sound-absorbent material. By placing the sound-absorbing material in the annular space, the resonances within this space are damped, thus alleviating their effect. The annular space can have a lower resonant frequency that is below the passband of the first driver. Essentially, instead of minimising the effect of the annular gap by reducing its size and seeking to seal its outer opening, we propose to enlarge the space so that the fundamental resonant frequency it exhibits drops out of the passband of the high-frequency driver and hence out of the frequency range of interest. This both prevents the fundamental frequency of the cavity from being excited, and also allows sufficient room within the space to accommodate a sound-absorbent material to absorb these undesirable resonances.

Loudspeaker

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.

Acoustic phase plug

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.

Electro acoustic diaphragm

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.

Loudspeaker with force cancelling configuration

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.

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.

Loudspeaker and diaphragm therefor

A loudspeaker comprises a reflex port located within the enclosure at a point substantially co-incident with a nodal surface of at least one resonant mode within the enclosure. The amplitude of that resonance at the input to the duct is minimized, hence assisting in filtering out the effect of that resonance without needing absorptive material. Ideally, it is placed at the intersection of two or more nodal surfaces.

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.

An electro-acoustic transducer with a front part having an acoustically radiating surface, a supporting part that supports the front part and that extends from a peripheral region of the front part in a direction away from the acoustically radiating surface, and a reinforcing part that provides rigidity to the transducer. The reinforcing part extends from the supporting part to the front part such that a portion of the reinforcing part is spaced from the front part and/or the supporting part.

Electro-acoustic transducer

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.

Phase plug

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.

Phase plug for compression driver

A loudspeaker comprises a horn waveguide having a waveguide surface, and a transducer located in, or adjacent to, a throat of the horn waveguide. The transducer has a substantially rigid convex dome-shaped acoustically radiating surface. A horn angle subtended between a longitudinal axis of the horn waveguide and the waveguide surface at the throat of the horn, is in the range 20 to 60 degrees. An intersection angle subtended between a plane tangential to the dome shape of the acoustically radiating surface and a plane tangential to the waveguide surface at a point where the dome shape or an extrapolation of the dome shape meets the waveguide surface or an extrapolation of the waveguide surface, is in the range 85 to 110 degrees.

Tangerine wave guide

An improved acoustic horn for loudspeakers is provided. The acoustic horn of the referred embodiment of the present invention includes a one piece body that incorporates damping material within the body. Preferably, the one piece body is slotted and vibration damping material is provided within the slots. The horn is fabricated by casting from suitable metals and metal alloys. In the preferred embodiment, the body comprises four outwardly curved and flared side walls and is generally rectangular. Each wall of a pair of the opposed side walls is cast with a slot. Vibration damping material is provided in each slot to substantially reduce the structural resonances of the one piece body, so that the acoustic horn has enhanced vibration damping. Various vibration damping materials that are flexible relative to the body and have a high loss tangent are used. Suitable materials include hot melt adhesives, epoxy resins, and commercially available elastomeric materials.

Growing community of inventors

Woodbridge, United Kingdom

Mark Alexander Dodd