GB2522055A - Loudspeaker system - Google Patents

Abstract

The loudspeaker system 1 wherein one or more drivers is used for each frequency band. One band, preferably high-frequency has one driver 10 mounted on an axis X- X, and the remaining one or more frequency bands each have a respective plurality of drivers 20A, 20B, 20C, 30A, 30B, 30C radially spaced on the circumference of an imaginary circle around the axis X-X, and a cross- over to drive the bands of drivers at different frequencies. Further arrangements are shown in the remaining figures.

Description

TIThE: Loudspeaker System The present invention relates to a novel loudspeaker system and especially to a multi-way loudspeaker system with an array of drivers are adapted to operate at two or more different frequency ranges.

It is known to create a multi-frequency band, e.g. two band or three (or more) band, loudspeaker system in which two or three (or more) drivers are spaced apart on a common plane. The driver/s in each "band" are adapted to operate at different frequency ranges and are fed through a crossover device which feeds the correct frequency range to the correct driver/s.

If different driver designs are used within the same loudspeaker system, they will occupy different physical positions. At the crossover centre frequency, the same signal is being fed to more than one driver and the acoustic output is the sum of the acoustic outputs from distance separated discrete sources. If, as is almost always the case, the physical location of the drivers is separated by more than the sum of the two driver's radii, and this distance is of the order of half the wavelength or greater anywhere in the overlap region, there will be certain points in space where the two outputs are non-coherent and ifill or partial acoustic cancellation occurs. If the ideal output is visualised as a uniform sphere of sound all around a loudspeaker system with a consistent spherical shape at all frequencies, these cancellations would look like dips in the surface, small and deep, wide and shallow and sometimes both wide and deep, the degree and position changing with change in frequency.

It is known to avoid this difficulty with what is known as co-axial or fri-axial loudspeakers where two or more drivers, each covering different frequency bands, are mounted on a common axis.

This however makes it hard to create a loudspeaker system with the drivers on a common plane without the transducers physically and acoustically interfering with each other. Various systems have been made each with their own drawbacks.

The invention seeks to provide an improved loudspeaker.

According to the present invention there is provided with a multi-frequency band loudspeaker system wherein each band comprises one or more drivers, one band having one driver and being mounted on an axis, and one or more bands each having more than one driver radially spaced on the circumference of an imaginary circle around the axis, and a cross-over to drive the bands of drivers at different frequencies.

Preferably the on axis driver covers the highest frequencies.

Preferably the bands of more than one drivers, have drivers which are equally radially spaced.

Preferably bands of more than one driver have at least three drivers, such as three or four (or more) drivers.

Drivers of each band may be on a common plane and/or or axially spaced.

Preferably the bands of drivers show rotational symmetry about said axis.

In one embodiment the drivers are mounted in a cabinet with a front wall, side walls and rear wall. Preferably the cabinet shows rotational symmetry about said axis Preferably the drivers in each band are mounted in a plane formed by the front wail or in the side walls. The front wall may be triangular, square or other regular polygon, with rectangular side walls. If the front wall is a regular polygon it may be preferred that one band on an axis passing through the centre of the front wall and one or more bands have a number of drivers equal to the order of polygon on said front wall and one or more bands on said side walls.

In one embodiment the front wall is triangular and has one band on an axis passing through the centre of the front wall and one or more bands have at least three drivers on said front wall and one or more bands on said side walls.

In another embodiment the front wall is rectangular and has one band on an axis passing through the centre of the front wall and one or more bands have at least four drivers on said front wall and one or more bands on said side walls.

Alternatively the driven are may be mounted in a common plane on a baffle or on a folded baffle. Preferably the baffle shows rotational symmetry about said axis.

An embodiment of the invention will now be described with reference to the accompanying drawings in which: Figure 1 shows a schematic perspective view of a loudspeaker system with a triangular front wall, Figure 2 shows a schematic perspective view of a loudspeaker system with a square front wall, and Figures 3A and 3B show schematic front views of loudspeakers systems of different configurations to that shown in Figures 1 and 2.

Referring to Figure 1 there is shown a 3-frequency band loudspeaker system 1 with 3-fold rotational symmetry.

System 1 has a housing 2 with a triangular front wall (or baffle) 3 a triangular rear wall 4, and three rectangular side walls 5,6,7. Housing 2 has an axis of symmetry X-X ninning through the centres of the front and rear walls. Housing 2 shows rotational symmetry about axis X-X.

A first band comprises one driver 10 mounted on the front wall 3 aligned on the axis X. Driver provides the highest frequency band (driver 10 could be a two or more component co-axial driver with each component providing frequencies making up the highest frequency band). A second band comprises three drivers 20A,20B,20C mounted on the front wall 3 spaced with rotational symmetry around the axis X-X (i.e. radially spaced on the circumference of the dotted circle around the axis). A third band comprises three driven 30A,308,30C mounted on side walls 5,6,7 spaced with rotational symmetry around the axis X-X (i.e. radially spaced on the circumference of the dotted circle around the axis). Driven 10 and 20A,20B,20C are on a common plane and drivers 30A,30B,30C are on a plane axially spaced from drivers 10 and 20A,20B,20C.

A cross-over (not shown but known in the all) is provided to drive the different bands, e.g. an active or passive cross-over amplifier system.

Referring to Figure 2 there is shown a 3-band loudspeaker system 40 with 4-fold rotational symmetry.

System 40 has a housing 42 with a rectangular front face (or baffle) 43, a rectangular rear face 4, and four rectangular side walls 45,46,47,48. Housing 42 has an axis of rotational symmetry X-X running through the centres of the front and rear walls.

A first band comprises one driver 50 mounted on the front wall 43 aligned on the axis X-X.

Driver 50 provides the highest frequency band (again driver 50 could be a two or more component co-axial driver with each component providing frequencies making up the highest frequency band). A second band comprises four drivers 60A,60B,60C,60D mounted on the front wall 43 spaced with rotational symmetry around the axis X-X (i.e. radially spaced on the circumference of the dotted circle around the axis). A third band comprises four drivers 70A,70B,70C,70D mounted on side walls 45,46,47,48 spaced with rotational symmetry around the axis X-X (i.e. radially spaced on the circumference of the dotted circle around the axis).

Drivers 50 and 60A,60B,60C,60D are on a common plane, and drivers 70A,70B,70C,70D are on a plane axially spaced from driven 50 and 60A,60B,60C,60D.

A cross-over (not shown but known in the art) are provided to drive the different bands.

Because the drivers in the loudspeaker systems I and 40 above are closely spaced with rotational symmetry around the axis X-X, minimum accoustic cancellation occurs. All drivers forming a frequency band' are preferably identical and optimised to provide good performance within that band while being small enough for the group to give wide dispersion at the HF part of its band.

All drivers used above the lowest frequency band preferably have their own sealed enclosures.

The LF band driver group may share the main cabinet volume.

The loudspeaker system of the invention may have two or more bands and other configurations to that shown in Figure 1 or 2. Figures 3A and 3B show how three bands may be mounted on a triangular or rectangular front face or baffle. The loudspeaker system of the invention may include an enclosed housing to provide a monopole system or a just a planar or folded baffle supporting unenclosed drivers for a dipole system.

The size and types of drivers may be selected as desired for different applications of a given loudspeaker system. If multiple identical driven are used in a physical configuration that is coaxial with another driver or group of drivers, the chosen number of drivers in the group has a big influence on the overall product design. In theory, any quantity could be used from 2 upwards; in practice 3 or 4 are optimum as cost and complexity increase with larger numbers.

We will consider groups of three and four in the following. Groups of four indicate square aspect cabinets or baffles. Three indicates a triangular cabinet or baffle, not a unique shape for a loudspeaker but unusual and one which can be made to work extremely well. It uses the lowest practical number of drivers.

The invention may take a form different to that specifically described above.

Further modifications will be apparent to those skilled in the art without departing from the scope of the present invention.

Claims (17)

1. CLAIMS1. A multi-frequency band loudspeaker system wherein each band comprises one or more drivers, one band having one driver and being mounted on an axis, and one or more bands each having more than one driver radially spaced on the circumference of an imaginary circle around the axis, and a cross-over to drive the bands of drivers at different frequencies.
2. 2. A loudspeaker system according to claim 1, wherein the on axis driver covers the highest frequencies.
3. 3. A loudspeaker system according to claim 1 or 2, wherein the bands of more than one driver, have drivers which are equally radially spaced.
4. 4. A loudspeaker system according to claim 1, 2 or 3, wherein bands of more than one driver have at least three drivers.
5. 5. A loudspeaker system according to any preceding claim, wherein drivers of each band may be on a common plane and/or or axially spaced.
6. 6. A loudspeaker system according to any preceding claim, wherein the bands of drivers show rotational symmetry about said axis.
7. 7. A loudspeaker system according to any preceding claim, wherein the drivers are mounted in a cabinet with a front wall, side walls and rear wall.
8. 8. A loudspeaker system according to claim 7, wherein the cabinet shows rotational symmetry about said axis
9. 9. A loudspeaker system according to claim 7 or 8, wherein the drivers in each band are mounted in a plane formed by the front wall or in the side walls.
10. 10. A loudspeaker system according to claim 7, 8 or 9, wherein the front wall is triangular or square, with rectangular side walls.
11. 11. A loudspeaker system according to any of claims 7th 10, wherein the front wall is a regular polygon and has one band on an axis passing through the centre of the front wall and one or more bands have a number of drivers equal to the order of polygon on said front wall and one or more bands on said side walls.
12. 12. A loudspeaker system according to claim 11, wherein the front wall is triangular and has one band on an axis passing through the centre of the front wall and one or more bands have at least three drivers on said front wall and one or more bands on said side walls.
13. 13. A loudspeaker system according to claim 11, wherein the front wall is rectangular and has one band on an axis passing through the centre of the front wall and one or more bands have at least four drivers on said front wall and one or more bands on said side walls.
14. 14. A loudspeaker system according to any of claims 1 to 6, wherein the drivers are maybe mounted in a common plane on a baffle.
15. 15. A loudspeaker system according to any of claims Ito 6, wherein the driven are may be mounted on a folded baffle
16. 16. A loudspeaker system according to claim 14 or 15, wherein the baffle shows rotational symmetry about said axis.
17. 17. A multi-frequency band loudspeaker system substantially as hereinbefore described with reference to and as shown in the accompanying drawings.