Abstract: An audio loudspeaker which includes a plurality of line source transducers arranged side by side and operated utilizing Bessel coefficient such that the loudspeaker as a whole operates as a line source within a line source operating frequency range. Optionally, the line source transducers may be operated in conventional line array fashion outside the frequency range in which the Bessel coefficients exhibit polar response benefit; for example, the line source transducers may all be driven with +1 coefficients below the Bessel coefficient frequency range to increase low frequency output. The loudspeaker may optionally include a tweeter that operates above the Bessel coefficient frequency range, and/or a woofer that operates below the Bessel coefficient frequency range.

Abstract: An electromagnetic transducer, such as an audio loudspeaker, having an underhung voice coil disposed in a magnetically tapered air gap. The taper provides asymmetry in the magnetic flux field. As the voice coil moves in one direction, the motor becomes stronger and more efficient, and as the voice coil moves in the other direction, the motor becomes weaker and less efficient. This results in an increase in even-order harmonics. The magnetic taper may result from a geometric taper of one or both of the opposing steel pieces which form the gap, or it may result from one or both of them having an at least partially laminated structure. The geometric taper provides a magnetic reluctance gradient along the height of the magnetic air gap. The laminated structure provides a magnetic reluctance gradient through the thickness of the laminated member (e.g. top plate). The magnetic reluctance gradient produces a magnetic flux density gradient along the height of the magnetic air gap.

Abstract: An electromagnetic transducer such as an audio speaker, having three or more voice coils disposed in one or more magnetic air gaps. The voice coils can be combined in any permutation of series/parallel connections, to select any one of a predetermined set of impedance values for the transducer. Optionally, the transducer is equipped with a set of different terminal connector plugs, each of which automatically performs the series/parallel connections for its designated impedance value. All voice coils may be selected as active, allowing for a constant maximum efficiency, regardless of which impedance option is selected.

Abstract: An electromagnetic transducer such as an audio speaker, having an air-return motor. The use of an air return geometry lacking motor components in the region outside the voice coil assembly permits the spider and cone to be coupled to the bobbin much lower, significantly reducing the thickness of the transducer. The use of both a radially-charged primary magnet and axially-charged concentrating magnets provides greatly increased magnetic flux in the voice coil region. The primary magnet may be a cylindrical magnet or it may include a plurality of flat magnet segments arranged in a polygon. The motor may be coupled to the frame by steel bolts which pass through holes in the spider, to reduce the reluctance of the magnetic circuit.

Abstract: One or two thermally conductive chimney tubes extend through a loudspeaker cabinet that encloses a volume of air heated by a speaker driver. The open ends of each chimney are outside the cabinet. A column of air within each chimney is in contact with the external ambient air, but sealed off from the enclosed volume of air. As the speaker driver heats the enclosed volume of air, the material of the chimney transfers the heat to the column of air, which rises and carries the heat away into the external ambient air, cooling the inside of the loudspeaker cabinet and thus cooling the speaker driver. A second chimney can be oriented perpendicular to the first, ensuring that one of them is vertical regardless of cabinet orientation. A single chimney can be oriented diagonally, ensuring some chimney effect regardless of cabinet orientation.

Abstract: An electromagnetic transducer such as an audio speaker, having a multi-gap air-return motor. The use of an air return geometry lacking motor components in the region outside the voice coil assembly permits the spider and cone to be coupled to the bobbin much lower, significantly reducing the thickness of the transducer. The use of multiple high-flux regions increases Xmax.

Abstract: An electromagnetic transducer such as an audio speaker, having a conical magnet, and an inner yoke and an outer yoke having conical surfaces for mating with the conical magnet. The conical magnet may be radially-charged, semi-radially-charged, or axially charged.

Abstract: An electromagnetic transducer, such as an audio loudspeaker, having an underhung voice coil disposed in a magnetically tapered air gap. The taper provides asymmetry in the magnetic flux field. As the voice coil moves in one direction, the motor becomes stronger and more efficient, and as the voice coil moves in the other direction, the motor becomes weaker and less efficient. This results in an increase in even-order harmonics. The magnetic taper may result from a geometric taper of one or both of the opposing steel pieces which form the gap, or it may result from one or both of them having an at least partially laminated structure. The geometric taper provides a magnetic reluctance gradient along the height of the magnetic air gap. The laminated structure provides a magnetic reluctance gradient through the thickness of the laminated member (e.g. top plate). The magnetic reluctance gradient produces a magnetic flux density gradient along the height of the magnetic air gap.

Abstract: A loudspeaker cabinet with a laminated internal brace which has a first rigid layer coupled to a first exterior panel of the cabinet, a second rigid layer coupled to an a second exterior panel of the cabinet, and a damping layer affixed between the rigid layers where they overlap. Vibration, flexure, and expansion/contraction of the cabinet are damped by shearing forces applied to the damping layer as the rigid layers move in opposite, parallel directions.

Abstract: A soundbar of loudspeakers for use with a television or the like. The soundbar includes two, three, or more Bessel Arrays configured to produce sound for a corresponding number of audio channels. To reduce the transducer count and/or the soundbar width, adjacent channels may share a transducer in their respective Bessel Arrays, and/or one or more of the channels may use a Reduced Bessel Array.

Abstract: An MTM loudspeaker in which the Ms and/or the T is constructed as a Bessel Array. The shapes of the diaphragms, the transducer count, the Bessel type, and/or the acoustic center positioning can be adjusted to achieve desired packing factor, enclosure size, off-axis performance, and so forth.

Abstract: An e.g. 7-element Bessel Array in which the null or zero positions are occupied with sound producing means producing sound outside the Bessel functional frequency range, such as a higher frequency Bessel Array, a higher frequency MTM, or a port.

Abstract: A dipole loudspeaker in which the oppositely oriented transducers each is a Bessel Array. Optionally, Improved or Super Bessel Arrays are used, and their half-amplitude end position transducers may be shared and aimed in a perpendicular—typically vertical—orientation. The Bessel Dipole is especially useful as a surround channel loudspeaker; for the same effective radiating area and/or sound production, the Bessel Dipole has a narrower cabinet than a conventional two-transducer dipole loudspeaker.

Abstract: A Bessel Array loudspeaker in which identical transducers are fed full amplitude signals. The half amplitude output at some Bessel positions can be achieved by angling those transducers to the side or up/down. The half amplitude transducers can be coupled to separate cabinets which can be rotated left/right with respect to the full amplitude transducers' cabinet, and the rotation can automatically reconfigure the wiring of the half amplitude transducers. The half amplitude output can alternatively be achieved by driving only half of the voice coil windings of the half amplitude transducers. The other half of their voice coil windings can optionally be driven via a low pass filter, to achieve an Improved Bessel with increased bass output and sensitivity.

Abstract: An optical disc drive including, in a separate sealed chamber, a magnetic disk drive which serves as a cache for the optical disc drive. The optical disc and the magnetic disk are carried on separate spindles which are non-coaxial. Optionally, the optical disc and the magnetic disk overlap.

Abstract: A loudspeaker in which an electromagnetic transducer drives a chamber-loaded augmented passive radiator (APR). The loudspeaker uses a bandpass enclosure such that the transducer produces sound pressure directly into a listening space, and the APR produces sound pressure into the listening space via an acoustic coupler through a chamber which loads the large diaphragm of the APR. The augmented passive radiator enhances low frequency output, permitting the use of a smaller electromagnetic transducer, which in turn improves high frequency output. This improved loudspeaker system may be used in stand-alone loudspeakers, in-ceiling or in-wall loudspeakers, automotive loudspeakers, pro-audio loudspeakers, and in other applications.

Abstract: A loudspeaker in which a compound driver drives an augmented passive radiator (APR). Either the compound driver and/or the APR may be coupled to the enclosure in a high-pass configuration such that it produces sound pressure directly into a listening space, or in a band-pass configuration such that it produces sound pressure into the listening space via an acoustically coupled loading chamber. The augmented passive radiator enhances low frequency output, permitting the use of a smaller electromagnetic transducer, which in turn improves high frequency output. This improved loudspeaker system may be used in stand-alone loudspeakers, in-ceiling or in-wall loudspeakers, automotive loudspeakers, pro-audio loudspeakers, and in other applications.

Abstract: A disk drive including two or more spindles each carrying one or more media platters. The disk drive may have an industry standard sized chassis. By using reduced diameter platters, two spindles' platters can be fit within the chassis, increasing the capacity and/or performance of the drive. The two spindles' platters may be of the same type, such as magnetic hard disk platters, or they may be different, such as one spindle of hard disk and one spindle of optical disk. Optionally, one spindle's platter may be used as a cache or buffer for the other spindle's platter.

Abstract: An audio speaker driver having a voice coil with graduated windings such that different sections of the voice coil have different electrical resistances and/or lengths per unit of height of the voice coil. A center portion of the voice coil gives a greater BL, while outer portions give lower overall electrical resistance, such that the audio speaker driver is highly efficient and linear during low excursion operation, with a smoother transition from the linear region to the grossly non-linear region. The wire of the graduated voice coil can have varying cross-sectional area over its length, can be wound on varying on-center spacing, can be wound in different numbers of layers in the various sections, and/or it can fork into interlaced, parallel windings.

Abstract: An improved Bessel array of electromagnetic transducers, in which the Bessel coefficients (phase and/or magnitude) are applied only in the useful high frequency range, where off-axis interference patterns between the outputs of respective transducers cause undesirable acoustic results. One improvement is in using an all-pass filter or the like in lieu of an inverter in the inverting Bessel coefficient path, to provide an in-phase signal in low frequencies and an opposite-phase signal in high frequencies. This achieves the improved off-axis result of a conventional Bessel array, with improved low-frequency maximum sound pressure and efficiency. Another improvement is in using a frequency-dependent voltage divider, such as a shelf circuit, in the half-strength Bessel coefficient paths, to provide full-strength signals in low frequencies and half-strength signals in high frequencies. This achieves even more improved low-frequency maximum sound pressure.