Purifi Aps

Dali A/s

Bruno Putzeys

Lars Risbo

Carsten Tinggaard

Morten Halvorsen

Kim Kristiansen

A motor for an electrodynamic loudspeaker and an electrodynamic loudspeaker including the motor. The motor includes a magnetic circuit assembly arranged about a motor axis. The motor includes: a magnetically permeable top plate, a magnetically permeable bottom plate, a magnetically permeable member disposed between, and magnetically coupled to, the magnetically permeable top and bottom plates, a center pole piece and an air gap for receipt of a voice coil. The motor also includes an outwardly projecting magnetically permeable member, or hat, arranged above a top of the air gap. The center pole piece includes a permanent magnet, such as a Neodymium magnet or a Ferrite magnet, extending axially from at least the bottom of the air gap to a magnetically permeable bottom member or to the magnetically permeable bottom plate.

Loudspeaker motor with inner permanent magnet

A loudspeaker with a non-uniform surround, a membrane and a stiffening element preventing the surround from flexing the membrane during operation. A non-uniform surround does not have the same cross section, along the radius of the speaker if circular, all around the perimeter of the membrane as some portions will be upwardly directed and other portions downwardly directed.

Loudspeaker with a non-uniform suspension and an enforcement element

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. The magnetic member exhibits a relative AC magnetic permeability smaller than 10, such as smaller than 5 or smaller than 2, such as about 1 which corresponds to the relative AC magnetic permeability of free air.

Loudspeaker motor with improved linearity

An amplifier, such as a Class D amplifier, having one or more feedback loops comprising a path from the input to the primary amplifier input, where the paths comprise a low pass filter and a compensator which is disabled when the primary amplifier clips.

Amplifier circuit

The present invention discloses a loudspeaker driver comprising a magnet system having at least one gap where in each gap a voice coil assembly is arranged for movement in the gap, wherein either two distinct coils are arranged on the voice coil assembly, one above the other, and the magnet system comprises two pole pieces, one above the other, creating a pair of magnetized areas between said pole pieces and a yoke, such that a magnetic flux field is created between each pole piece and the yoke. In an alternative two concentric gaps are provided, where the voice coil assembly comprises two concentrically arranged sub-voice coils, where each sub-voice coil is provided with a distinct voice coil and the magnet assembly has two concentrically arranged magnet rings arranged with a yoke in the center, such that two concentric gaps are created, and that the voice coil assembly moves substantially orthogonal to the flux fields in the gap(s) and further that at least the part of each pole piece facing the gap(s) is made from a soft magnetic composite (SMC) material.

Double voice coil loudspeaker transducer unit

A Class D amplifier having an integrating primary amplifier with an internal feedback, the amplifier further comprising a feedback loop with a filter of at least second order.

Amplifier with an at least second order filter in the control loop

An amplifier comprising a gain stage with a feedback network comprising two ports between which at least three capacitors are connected in series and between each pair of capacitors a resistor is connected to a predetermined voltage. The gain stage is provided in a feedback loop over a primary amplifier.

Amplifier with a compensator with a network of at least third order

The present invention relates in one aspect to a method of controlling or limiting diaphragm excursion of a loudspeaker. The method comprising steps of receiving a first audio signal and deriving an excursion signal representing diaphragm excursion of the electrodynamic loudspeaker from the first audio signal. The method additionally comprises deriving an excursion envelope from the excursion signal and applying a second audio signal, derived from the first audio signal, to an input of an adjustable low-frequency suppressor. The second audio signal is filtered by the adjustable low-frequency suppressor to selectively attenuate low-frequency components based on the excursion envelope to produce a processed audio signal with reduced low-frequency content.

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Achel, Belgium

Bruno Putzeys