# US 2014/0211963 A1 · Loudspeaker with force cancelling configuration

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- Number: US 2014/0211963 A1
- Document ID: US20140211963A1
- Status: Published application
- Kind: A1
- Application number: 14/117,290
- Filed: 2012-05-18
- Published: 2014-07-31
- Earliest claimed: 2011-05-18
- Assignees: GP Acoustics (UK) Limited
- Applicants: GP Acoustics (UK) Limited
- Inventors: Mark Alexander Dodd
- Web page: https://patentgrep.com/patent/US20140211963A1

## CPC

- H04R 9/063: {using a plurality of acoustic drivers (H04R1/24 and H04R1/403 take precedence)}
- H04R 1/2896: {for loudspeaker transducers}
- H04R 7/12: Non-planar diaphragms or cones
- H04R 1/288: {for loudspeaker transducers}
- H04R 7/04: Plane diaphragms
- H04R 2209/027: Electrical or mechanical reduction of yoke vibration
- H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K)

## 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.

## Claims

### Claim 1

A loudspeaker, comprising:
a first diaphragm and a respective first drive assembly, the first drive assembly comprising at least a first magnet;
a second diaphragm and a respective second drive assembly, the second drive assembly comprising at least a second magnet; and
a coupling member connecting the first magnet to the second magnet, said coupling member comprising a non-rigid material arranged such that forces are conveyed from the first magnet to the second magnet and vice versa, but that vibrations in the coupling member are damped.

### Claim 2 (depends on 1)

The loudspeaker according to claim 1, wherein the first and second drive assemblies and the coupling member have dimensions so as to result in resonance at a resonant frequency.

### Claim 3 (depends on 2)

The loudspeaker according to claim 2, wherein the addition of the coupling member results in a system Q factor of less than 5 at said resonant frequency.

### Claim 4 (depends on 3)

The loudspeaker according to claim 3, wherein the addition of the coupling member results in a system Q factor of less than 0.5 at said resonant frequency.

### Claim 5 (depends on 1)

The loudspeaker according to claim 1, wherein the non-rigid material is a viscous material.

### Claim 6 (depends on 5)

The loudspeaker according to claim 5, wherein the viscous material is retained in its position by a visco-elastic member.

### Claim 7 (depends on 1)

The loudspeaker according to claim 1, wherein the non-rigid material is a visco-elastic material.

### Claim 8 (depends on 1)

The loudspeaker according to claim 1, wherein the non-rigid material is adhesive.

### Claim 9 (depends on 8)

The loudspeaker according to claim 8, wherein the non-rigid material provides a clamping force F between the first and second magnets of:
F>2IBl
where I is the current flowing in a voice coil of the first or second drive assembly, and Bl is the force generated by 1 ampere of current flowing through the voice coil.

### Claim 10 (depends on 1)

The loudspeaker according to claim 1, wherein the non-rigid material comprises Blu Tack (®), mastic, putty or butyl mastic.

### Claim 11 (depends on 1)

The loudspeaker according to claim 1, wherein the non-rigid material is formed into a disc.

### Claim 12 (depends on 1)

The loudspeaker according to claim 1, further comprising a box in which the first and second diaphragms and the first and second drive assemblies are mounted.

### Claim 13 (depends on 12)

The loudspeaker according to claim 12, wherein the box is wooden or plastic.

### Claim 14 (depends on 1)

The loudspeaker according to claim 1, wherein the first and second diaphragms and the first and second drive assemblies are substantially identical.

### Claim 15 (depends on 1)

The loudspeaker according to claim 1, wherein the first and second drive assemblies are mounted and wired such that the forces acting on the magnets substantially cancel.

### Claim 16 (depends on 2)

The loudspeaker according to claim 2, wherein the non-rigid material is a visco-elastic material.

### Claim 17 (depends on 3)

The loudspeaker according to claim 3, wherein the non-rigid material is a visco-elastic material.

### Claim 18 (depends on 4)

The loudspeaker according to claim 4, wherein the non-rigid material is a visco-elastic material.