GB2435729A

GB2435729A - A slot-loaded loudspeaker enclosure with curved walls

Info

Publication number: GB2435729A
Application number: GB0604254A
Authority: GB
Inventors: Mark Treanor
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-03-03
Filing date: 2006-03-03
Publication date: 2007-09-05
Anticipated expiration: 2026-03-03
Also published as: GB0604254D0; GB2435729B

Abstract

The loudspeaker 2 comprises a body 4 having an inlet and an outlet formed by a curved front wall 14, a curved rear wall 12 and two mutually parallel sidewalls. The outlet opens at the slot 30 and the inlet accommodates a loudspeaker driver mounted within an acoustic low-pass filtering housing 32. Discs 20 may be mounted within the enclosure to affect standing waves. A further embodiment (figs 3 and 4) makes use of two such bodies. The pressure and the velocity of the sound waves within the enclosure are affected by both the low-pass filtering housing 32 and the loading slot 30.

Description

A Speaker The invention relates to a speaker system. Particularly, the

invention relates to a horn type speaker system.

A loudspeaker, or driver, is an electromechanical transducer which converts an electrical signal into sound.

Traditionally, a loudspeaker comprises a coil of wire mounted in a cone. A permanent magnet is provided close to the coil to induce a magnetic field upon application of an electrical signal. The magnetic field causes vibration of the coil and the cone. The vibration produces sound at the frequency of the applied electrical signal. When a multi-frequency signal is applied, a complex vibration occurs, which causes reproduction of the applied signal as an audio signal.

Sound emanating from a loudspeaker can be characterised into three ranges: a low range which includes bass frequencies, generally between 50Hz to 3KHz; a mid-range, generally between 200Hz to 5KHz; and a high range, generally between 1KHz to 35KHz. A single driver is often capable of producing sound across the whole range of frequencies. In particular, it is understood that the source of high range notes is more easily determined by a listener, whereas a source position of low range notes is more difficult to discern. This leads to problems with noise cancellation because the low range notes, or multi directional notes, tend to cancel out the high range higher notes. This effect impacts on the quality of sound coming from the speaker. In order to overcome this problem a baffle is often used to redirect the low range notes away from the high range notes.

The driver is usually mounted in a housing or enclosure.

The housing helps to prevent noise interference and cancellation and so provides a better quality of sound from the loudspeaker. A particular type of enclosure is the horn speaker in which the enclosure flares outwardly in a cone shape. It is commonly accepted that domestic horn loudspeakers produce very little deep bass and are generally, overly large in size. Therefore, such speakers are impractical to use in domestic environments. The problem of producing bass sound is not easily overcome because as the size of the enclosure is reduced, the quality of the bass sound emanating from the loudspeaker system becomes diminished.

It is an object of the present invention to provide a domestic full range horn speaker system with improved acoustical bass quality.

According to a first aspect of the present invention, there is provided a speaker comprising a body having an inlet and an outlet formed by a front wall and a rear wall, a first sidewall and a second sidewall; at least one driver located at the inlet that is operable to produce sound waves; and a baffle; wherein the front wall and the rear wall are curved and wherein said sidewalls are substantially parallel to each other.

Preferably, the centre of the curve of the front wall is offset from the centre of the curve of the rear wall.

Preferably, the radius of curvature of the rear wall is greater than the radius of curvature of the front wall.

Preferably, the radius of curvature of the rear wall is between substantially two times and six times greater than the radius of curvature of the front wall, more preferably substantially four times greater.

The radius of curvature is large in the rear wall because the curve turns less sharply than it does for the front wall.

Preferably, the curve of the front wall is substantially semicircular. Preferably, the curve of the rear wall is substantially semicircular.

Preferably, the centre of the front wall is parallel with an edge of the rear wall.

According to a further aspect of the present invention, there is provided a speaker comprising a body having an inlet, an outlet, and a wall therebetween; at least one driver located at the inlet and operable to produce sound waves; and a baffle, wherein the inlet is adapted to provide sound waves at high pressure and low velocity, and the outlet is adapted to provide sound waves at higher pressure and lower velocity.

Preferably, the baffle is adapted to filter higher frequencies, and is preferably a reflex baffle.

Advantageously, the speaker arrangement acoustically amplifies bass frequencies. Further, the arrangement produces rather than reduces the amount of bass resonance emanating from the speaker. The effect is to produce an improved quality of bass sound.

Preferably, an enclosure is provided which is adapted to house the body. Most preferably, the enclosure is manufactured from materials having a thickness of substantially between 0.5cm and 2cm, most preferably substantially 1.25cm. Preferably, the enclosure is manufactured from wooden materials.

Preferably, the wall of the speaker is manufactured from materials having a thickness of substantially between 0.5cm and 2cm, most preferably substantially 1.25cm.

Preferably, the wall is manufactured from wooden materials.

The wall may include the rear wall or the front wall and/or said sidewalls of the first aspect of the invention.

Preferably, a base of the speaker is manufactured from materials having a thickness of substantially between 0.5cm and 5cm, preferably between substantially 3cm and 4cm, most preferably substantially 3.75cm. Preferably, the base is manufactured from wooden materials.

Unlike known domestic horn enclosures which are manufactured from thick, heavy construction materials, the enclosure of the present invention has thin walls. In so doing, the effect is to produce bass resonance, rather than eliminate bass resonance. In this manner, the speaker is acting as both a bass horn and a bass resonator.

Preferably, the rear wall has an internal diameter of between substantially 40cm and. 120cm. Preferably, when the speaker is a single driver horn speaker, the rear wall has an internal diameter of between 100 and 110cm, most preferably substantially 106cm. Preferably, when the speaker is a dual horn driver speaker, the rear wall has an internal diameter of between substantially 40cm and 65cm, most preferably 59.5cm.

Preferably, the front wall has a diameter of between substantially 10cm and 30cm. Preferably, when the speaker is a single driver horn speaker, the front wall has an internal diameter of between 20cm and 30cm, most preferably substantially 25cm. Preferably, when the speaker is a dual horn driver speaker, the front wall has an internal diameter of between substantially 12cm and 15cm, most preferably substantially 13.5cm.

Preferably, when the speaker is a single horn speaker, the rear wall is substantially between 45cm and 55cm in height from the front panel of the speaker. Most preferably, substantially 50.5cm. Preferably, the front wall is substantially between 12cm and 30cm in height from the front panel of the speaker. Most preferably, substantially 24.5cm.

Preferably, when the speaker is a dual horn speaker, the rear wall is substantially between 20cm and 30cm in height from the front panel of the speaker. Most preferably, substantially 26.5cm. Preferably, the front wall is substantially between 5cm and 15cm in height from the front panel of the speaker. Most preferably, substantially 13.5cm.

Preferably, at least one disc is located on the body.

Most preferably, two discs are provided. Preferably, each said disc has a diameter of substantially 21cm.

Preferably, the driver is located in a driver housing, preferably centrally thereof. Preferably, the driver has a diameter between substantially 8cm and 25cm.

Preferably, the driver has a diameter between substantially 9cm and 12cm, most preferably substantially 10cm.

Preferably, the driver housing is generally rectangular in shape and preferably has a cross sectional area of between substantially 200cm2 and 400cm2, most preferably substantially 382.25cm2. Preferably, the driver housing is located in a front panel of the speaker. Preferably, the driver housing is located towards a top portion of the speaker. Alternatively, the driver housing may be located centrally of the front panel, preferably when the speaker is a dual horn speaker.

Preferably, the driver housing is manufactured from materials having a thickness of substantially between 1cm and 2cm, most preferably substantially 1.5cm. Preferably, the driver housing is manufactured from wooden materials.

Preferably, a port is located in the driver housing.

Preferably, the port is located at the rear of the driver housing. Preferably, the port has an internal diameter preferably, substantially between 1.5cm and 10cm. Most preferably, substantially between 1.5.cm and 2.4cm.

Preferably, the port is substantially between 1.5cm and 10.5cm in length. Most preferably, substantially between 9.5cm and 10.5cm. Most preferably, substantially 10.3cm.

Preferably, the port projects inwardly of the driver housing.

Preferably, a baffle is located in the body, preferably in the driver housing. Most preferably, the baffle is located between the port and the driver. Preferably, the baffle extends from a portion of the rear wall to a portion of the front wall.

Preferably, a front panel is located on the body.

Preferably, the front panel extends from the front wall preferably towards the outlet of the speaker. In an alternative arrangement shown as a dual horn speaker, a front panel further extends upwards towards the inlet. In this arrangement, an outlet, or mouth of the speaker, is created at both the top and bottom of the speaker.

Preferably, the outlet, or mouth, is located towards an end of the speaker. Preferably, the outlet is substantially rectangular in cross section. Preferably, the outlet has a longitudinal length of between substantially 15cm and 35cm, most preferably substantially 2 5cm.

Preferably, the outlet has a height of substantially between 0.1cm and 100cm, preferably substantially between 0.5cm and 5cm, most preferably 4cm. In the preferred arrangement, the outlet is substantially 25cm in width and substantially 4cm in height, preferably having an approximate area of substantially 100 cm2.

The invention provides a domestic horn loudspeaker which incorporates a 10cm driver (or 4inch driver) operating in reflex mode to produce a deep accurate bass. In combination with the enclosure construction, the speaker of the invention produces improved quality of sound across a full range, at least 65Hz to 25KHz.

All of the features described herein may be combined with any of the above aspects, in any combination.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, wherein: Figure 1 is a schematic sectional side view of a horn speaker; Figure 2 is a schematic front view of a horn speaker; Figure 3 is a schematic sectional side view of a horn speaker; and Figure 4 is a schematic front view of the embodiment of Figure 3.

Figure 1 shows a horn speaker 2 according to the present invention. The horn speaker 2 comprises a body 4 having a top portion 6, a bottom portion 8, a front panel 10, a rear wall 12 or outer curved portion, and a front wall 14 or an inner curved portion 14. The diameter of the rear wall 12 is approximately 106cm and the diameter of the front wall 14 is approximately 27cm. An apex 16 of the inner curved portion 14 is approximately 13.5cm from the front panel 10. The apex 16 is offset from a corresponding apex 18 of the outer curved portion 12. The apex 18 is approximately 52cm from the front panel 10.

Two discs 20 are located on an inner surface 22 of the body 4. The discs 20 each have a diameter of approximately 21cm.

The body 4 is surrounded by an outer casing 24 which extends from the top portion 6, to form a shoulder 26 and then curves downwardly to extend around the body 4 towards the bottom portion 8 of the horn speaker 2. Adjacent the bottom portion 8, the outer casing 18 extends inwardly to form a concave cutout 28, and then outwardly to meet the bottom portion 8.

A mouth 30 is located adjacent the base portion 8. The mouth 30 is generally rectangular in shape and extends across the whole length of the base portion 8, from the outer curved portion 12, to meet the inner curved portion 14. The mouth 30 is shown by the hatched lines in Figure 2. The mouth 30 is defined by the front panel 10 which extends downwardly from the inner curved portion 14 towards the bottom portion 8 as shown in Figures 1 and 2.

The mouth 30 is approximately 25cm in width and 4cm in height.

A driver housing 32 is provided between the upper part of the front wall 14 and the top portion 6 of the horn speaker 2. The driver housing 32 is generally rectangular in cross section having a height of approximately 21.5cm and, a length of approximately 15.5cm. The driver housing is fitted into the horn speaker 2 such that a front part 34 thereof extends forwardly from the front panel 10. A driver 36 is located at the front of the driver housing 32 in a front wall 38. The driver 36 is located approximately centrally of the front wall. The driver 36 has a diameter of approximately 10cm to 11cm and is of a type known as a Fostex (RTM) driver. An alternative driver would be the type known as an NXT (RTM) driver, probably 10cm to 11cm in diameter. A baffle 40 is provided towards the rear of the driver 36. The baffle 40 extends from the inner curved portion 14 to join the Outer curved portion 12. A port 42 is located in a rear wall 44 of the driver housing 32. The port 42 projects inwardly by approximately 10.3cm towards the baffle 40. The port 42 has a diameter of approximately 1.5cm. However, a port having a diameter of 2.4cm would be equally suitable.

The outer casing 24 provides a skin around the body 4 of the horn speaker 2. The outer casing 24 is approximately between 1.2mm and 1.3mm thick as represented by X in Figure 2.

Figure 3 shows an alternative embodiment of a horn speaker in accordance with the present invention. The horn speaker 100 comprises a pair of rear walls outer curved portions 112 and a pair of corresponding front walls or inner curved portions 114. The diameter of each rear wall 112 is approximately 44cm. The diameter of each front wall 114 is approximately 13.5cm. Said outer and inner portions are arranged in the same offset manner to those shown in Figure 1. A disc 120 is provided in each outer curved portion 112, being located towards the top portion 106 and bottom portion 108 respectively.

A driver housing 132 is located centrally of the horn speaker 100 and between the pair of front walls 114. The driver housing 132 comprises a driver 136 mounted in a front wall 138. A baffle 140 is provided upstream of the driver 136. The baffle 140 extends across the driver housing 132 to join together the inner curved portions 114. The port 142 is located on a rear wall 144 of the driver housing 132. The port 142 is located centrally of said rear wall 144. The port 142 has a diameter of 1.5cm and 2.4cm and extends inwardly towards the rear of the driver 136 by approximately 1.5cm. The port 142 lies along generally the same plane as the driver 136 and an apex 148 of the outer curved portions 112.

In the embodiment shown in Figure 3, two mouths 130 are provided on the body 104. One mouth 130 is located adjacent to the top portion 106 and one mouth 130 is located adjacent to the bottom portion 108. Said mouths are approximately the same width, 25cm, as those shown for the single horn speaker. However, each of the mouths of the dual horn are 2cm in height, whereas the corresponding mouths of the single horn are 4cm in height.

The mouth area of both speakers is the same.

Alternatively as with the single horn, the dual horn speaker can be used without the two front panels.

Therefore, in this arrangement, each mouth 130 would measure 25cm in width and 26.5cm in height. The total mouth area would be approximately 1325cm2.

The body 104 is housed in an outer casing 124 which extends around the outer curved portion 112. The outer casing 124 is approximately 12mm to 13mm in width as shown as shown by distance X in Figure 4 In use, the horn speaker 2, 100 is connected to a power source, generally an alternating current, and is provided with an input signal to cause vibration of the driver 36, 136. The driver 36, 136 produces a full range of frequencies of sound. The baffle 40, 140 operates to separate the high range and the low range sound so that the low range sound waves are directed towards the rear wall 44, 144, of the driver housing 32, 132.

Due to the arrangement of the driver housing 32, 132, and the curved outer portion 12, 112, and the curved inner portion 14, 114, a high air pressure is created in the region of the port 42, 142, and a low velocity of air movement, by movement of the driver 36, 136. The low range noise is directed around the body 4 of the horn speaker 2, 100 passing the disks 120 which help to reduce standing waves, and are directed out of the horn speaker 2, 100 via each mouth 30, 130. The configuration of the mouth 30,130 acts to maintain a high pressure and low velocity for sound transmission through the horn speaker 2, 100. The result is a horn speaker which produces deep, fast accurate bass sound.

The horn speaker acoustically amplifies the bass frequencies produced by the driver 36, 136. The speaker according to the invention produces, rather than reduces, the amount of bass resonance heard. This is due to the construction of the enclosure being thin walled which not only acoustically amplifies bass frequencies but audibly produces an amount of bass resonance as well.

Any modifications will be apparent to the skilled user.

For example, any bass driver, with or without an internal throat inside the horn enclosure, mounted on the baffle or, a one way bass reflex enclosure mounted through the baffle or replacing the baffle importing into the horn enclosure. Further, any two way, mid or bass, treble drive combination (with or without an internal throat inside the horn enclosure) mounted on the baffle or, any two way reflex enclosure utilising any mid or bass, treble driver combination mounted through the baffle or replacing the baffle importing the horn enclosure. A further example would include any full range driver (with or without an internal throat inside the horn enclosure) mounted on the baffle or any one way, full range driver reflex enclosure mounted through the baffle or replacing the baffle importing into the horn enclosure.

Advantageously, the arrangement of the present invention provides a horn type speaker which produces a quality bass sound. The configuration of the horn speaker allows for a reduced size speaker system as compared to those known in the art. Particularly, when the enclosure is manufactured from wood materials, the quality of the bass sound is maximised and the weight of the horn speaker system is minimised. Furthermore, the horn speaker system of the present invention operates at a sound pressure level of approximately 90dB and operates at approximately 30W.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

S

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings) , and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) , may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment (s) . The invention extends to any novel one, or any novel combination, of the features

disclosed in this specification (including any

accompanying claims, abstract and drawings) , or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS

1. A speaker comprising a body having an inlet and an outlet formed by a front wall and a rear wall, a first sidewall and a second sidewall; at least one driver located at the inlet that is operable to produce sound waves; and a baffle; wherein the front wall and the rear wall are curved and wherein said sidewalls are substantially parallel to each other.

2. A speaker as claimed in claim 1, wherein the centre of the curve of the front wall is offset from the centre of the curve of the rear wall. * S ****

3. A speaker as claimed in claims 1 or 2, wherein the' radius of curvature of the rear wall is greater than the'.: radius of curvature of the front wall. *, * * *

4. A speaker as claimed in claim 3, wherein the radius of' curvature of the rear wall is substantially four times.".

S

greater than the radius of curvature of the front wall.

5. A speaker as claimed in any one of the preceding claims, wherein the curve of the front wall is substantially semicircular, and the curve of the rear wall is substantially semicircular.

6. A speaker as claimed in any one of the preceding claims, wherein the centre of the front wall is parallel with an edge of the rear wall.

7. A speaker comprising a body having an inlet, an outlet, and a wall therebetween; at least one driver located at the inlet and operable to produce sound waves; and a baffle, wherein the inlet is adapted to provide sound waves at high pressure and low velocity, and the outlet is adapted to provide sound waves at higher pressure and lower velocity.

8. A speaker as claimed in any one of the preceding claims wherein the baffle is adapted to filter higher frequencies.

9. A speaker as claimed in claim 8, wherein the baffle is a reflex baffle.

10. A speaker as claimed in any one of the preceding S.....

claims wherein an enclosure is provided which is adapted:.

to house the body. : ..

S S..

11. A speaker as claimed in claim 10, wherein the..: enclosure is manufactured from materials having a S...

thickness of substantially between 0.5cm and 2cm.

S S.

12. A speaker as claimed in any one of the preceding claims wherein the wall of the speaker is manufactured from materials having a thickness of substantially between 0.5cm and 2cm.

13. A speaker as claimed in any one of the preceding claims wherein the rear wall has an internal diameter of between substantially 40cm and 120cm.

14. A speaker as claimed in any one of the preceding claims wherein when the speaker is a single driver horn speaker, the rear wall has an internal diameter of between and 110cm.

15. A speaker as claimed in any one of claims 1 to 13, wherein when the speaker is a dual horn driver speaker, the rear wall has an internal diameter of between substantially 40cm and 65cm.

16. A speaker as claimed in any one of the preceding claims wherein at least one disc is located on the body, said disc having a diameter of substantially 21cm.

17. A speaker as claimed in any one of the preceding claims wherein the driver is located in a driver housing, the driver housing being located in a front panel of the speaker. : ..

S S..

18. A speaker as claimed in any one of the preceding:..

claims wherein a port is located in the driver housing, the port being located at the rear of the driver housing. .,..

19. A speaker as claimed in claim 18, wherein a baffle is located between the port and the driver.

20. A speaker as claimed in any one of the preceding claims wherein a front panel is located on the body, the front panel adapted to extend from the front wall towards the outlet of the speaker.

21. A speaker as claimed in any one of the preceding claims wherein the outlet is located towards an end of the speaker, and is substantially rectangular in cross section.

22. A speaker as substantially as hereinbefore described with reference to any one of the accompanying drawings. * * S.... U. * * S * * S* e * * S * * ** S... * S *55*

SSU S * S S.