GB2538785A

GB2538785A - Horn arrangement

Info

Publication number: GB2538785A
Application number: GB1509207.5A
Authority: GB
Inventors: John Andrews Anthony; Newsham John
Original assignee: FUNKTION ONE RES
Current assignee: FUNKTION ONE RES
Priority date: 2015-05-28
Filing date: 2015-05-28
Publication date: 2016-11-30
Also published as: GB201509207D0

Abstract

The horn comprises a first opening at an inlet; a second opening at an outlet, wherein the second opening is substantially rectangular; a wall connecting the first and second openings, wherein the wall comprises opposed upper and lower wall portions 308a, 308b that are divergent towards the second opening and at least a part of which are substantially planar, wherein an angle between the upper and lower wall portions is less than 30 degrees. This horn arrangement is said to give improved uniformity of sound distribution.

Description

Horn Arrangement

Technical Field

The invention relates to horns (or waveguides) for audio drivers, loudspeakers and columns of loudspeakers. In particular, the invention relates to loudspeaker horns, loudspeakers and columns of loudspeakers for high power audio output.

Background

Conventionally, loudspeakers have been used in different settings for delivering music and/or other audio output such as speeches. Loudspeakers may be used for producing and directing high power music audio output. High power music audio output may be required for large indoor or outdoor events such as music concerts. There is a need at such events for audio output to be distributed amongst an audience that may cover a large area such as a field. Taking the example of an outdoor music concert, some members of the audience may be located close to an audio output (the output situated at a stage, for example), whilst other members may be located far away from the audio output. For example, some members of the audience may be listening to the music from the back of a field which is hosting the concert. Therefore, there is a need to ensure that members of an audience close to an audio output and far away from the audio output are delivered good, and preferably the same, sound quality. It is also important that the audio output that they receive is of sufficient volume.

For the purposes of this disclosure, large-scale events can be taken to mean events composing an audience of over 100 people where audio is delivered to the audience by some means. The term high-power audio output encompasses audio transmitted to large arenas, concerts and outdoor spectator events. Typically, high-power audio will produce a sound level of 100 dB or more at a distance of 15 metres from the source.

Different loudspeaker arrangements and configurations have been developed to deliver even distributions of audio at large-scale events. To distribute audio evenly at large-scale events, sound reinforcement may need to be utilised. A sound reinforcement system may make use of a plurality of loudspeakers. Each loudspeaker comprises an electro-acoustic driver housed in some form of enclosure with the diaphragm of the driver radiating directly into the environment and to an audience of listeners. In a sound reinforcement arrangement, a plurality of individual loudspeakers may be arranged such that their outputs coalesce and form higher amplitude acoustic waves.

In addition, as part of a loudspeaker arrangement, loudspeaker horns may be utilised.

Loudspeaker horns are configured to receive an audio driver output. A loudspeaker horn may form part of a loudspeaker itself. Loudspeaker horns comprise two basic functions. A first function relates to loading of the driver to provide efficient operation at the working frequencies of the driver. A second function relates to direction control. A sidewall of the horn restricts the spreading out of waves, so that the sound is focused on an intended area.

For the purposes of this disclosure, the term "high-frequency" or "high-frequency audio" encompasses audio waves with frequencies greater than approximately 4 kHz.

Problems exist with high power high frequency audio output in that it is difficult to achieve the desired power with a single audio driver.

Summary of the Invention

The inventors have appreciated that it is desirable for a large audience to receive even distribution of low and high frequencies. However, it can be difficult to project high-frequency acoustic waves to an audience evenly and, in particular, deliver high-frequency acoustic waves to portions of the audience far away from a loudspeaker.

The difficulties stem from the small size and commensurate low energy of the wavelengths of acoustic waves in the high frequency band. In addition, the speed of diaphragm vibration for high-frequency sound requires a diaphragm of low mass, which contradicts the requirements for strength and power handling and this is also problematic. To vibrate at high-frequencies requires a strong magnetic force and light-weight diaphragms in audio drivers. This means that high-power high frequency audio is difficult to achieve.

The inventors have appreciated that sound reinforcement must be used to produce high-power audio at high-frequency that can project long distances, e.g. to the back of an audience at a large-scale event.

The inventors have further appreciated that sound reinforcement for high-frequency music audio output can result in a reduced sound quality. Diffraction of acoustic waves as they leave a loudspeaker horn and interference with acoustic waves from adjacent loudspeaker horns can lead to reduced sound quality. The interference may mean that if a listener moves only slightly they may receive acoustic waves with a significantly different volume.

According to the invention in a first aspect, there is provided a loudspeaker horn for high power music audio output, the horn comprising: a first opening at an inlet; a second opening at an outlet, wherein the second opening is substantially rectangular; a wall connecting the first and second openings, wherein the wall comprises opposed upper and lower wall portions that are divergent towards the second opening and at least a part of which are substantially planar, wherein an angle between the upper and lower wall portions is less than 30 degrees.

Optionally, the opposed planar upper and lower portions diverge towards the second opening at a relative angle in a range from 10 to 26 degrees.

Optionally, a height of the second opening is in a range from 10 cm to 15 cm.

Optionally, the height of the second opening is one of 12.2 cm and 10.95 cm.

Optionally, the height of the second opening is at least half the wavelength of the lowest frequency sound waves of the audio output.

Optionally, the lowest frequency sound waves are substantially 4 kHz.

Optionally, a vertical edge of the second opening is rounded.

Optionally, a distance from the first opening to the second opening is in a range from 15cm to 30cm.

Optionally, the first opening at the inlet of the horn is substantially circular.

According to the invention in a second aspect, there is provided a loudspeaker horn arrangement comprising a plurality of adjacent loudspeaker horns as described above.

Optionally, the plurality of loudspeaker horns are vertically aligned.

Optionally, an upper horizontal edge of a second opening of a first loudspeaker horn is adjacent a lower horizontal edge of a second opening of a second loudspeaker horn.

Optionally, the adjacent upper and lower horizontal edges abut to form an interconnecting edge.

Optionally, the interconnecting edge substantially forms a vertex.

Optionally, the vertex is rounded at a radius of less than 5mm.

Optionally, an internal angle between adjacent loudspeaker horns is less than 25°.

Optionally, the internal angle between adjacent loudspeaker horns is in a range from 20 to 21 degrees.

Optionally, central axes of adjacent loudspeaker horns converge in a direction towards the first openings.

Optionally, the relative angle between central axes of adjacent loudspeaker horns is in a range from 0.1° to 6°.

Optionally, a distance between the first openings of adjacent loudspeaker horns is at least 10 cm.

Optionally, a distance between the first openings of adjacent loudspeaker horns is substantially 12.5 cm.

Optionally, the interconnecting edge protrudes from a plane of the second openings of the adjacent loudspeaker horns.

Optionally, the wall comprises opposed vertical wall portions divergent towards the second opening, wherein an angle between the horizontally opposed substantially planar sidewall portions is substantially 90 degrees.

Optionally, the loudspeaker horn arrangement comprises two adjacent loudspeaker horns only.

Optionally, the sidewall comprises opposed vertical wall portions divergent towards the second opening, wherein an angle between the horizontally opposed substantially planar sidewall portions is substantially 65 degrees.

Optionally, the loudspeaker horn arrangement comprises three adjacent loudspeaker horns.

According to the invention in a third aspect, there is provided a loudspeaker arrangement comprising a loudspeaker horn arrangement described above and a plurality of audio drivers, each audio driver configured to emit audio into a loudspeaker horn of the loudspeaker horn arrangement.

According to the invention in a fourth aspect, there is provided a column of loudspeakers comprising a loudspeaker arrangement as described above.

Brief description of drawings

Exemplary embodiments of the invention are disclosed herein with reference to the accompanying drawings, in which: Figure 1 is a diagram showing interference of acoustic waves from two adjacent sources; Figure 2 is a diagram showing coalescence of acoustic waves from two adjacent sources after guiding; Figures 3a-3c are diagrams showing a loudspeaker horn arrangement; and Figures 4a-4c are diagrams showing a loudspeaker horn arrangement.

Detailed description

Generally, disclosed herein are exemplary loudspeaker horns configured to cause acoustic waves emitted therefrom to coalesce with acoustic waves emitted from an adjacent source. A plurality of loudspeaker horns may be placed adjacent to each other such that the acoustic waves emitted from each coalesce into a single acoustic wave. That is, the output of each loudspeaker horn constructively interferes with the output of the other loudspeaker horn to produce a single acoustic wave of greater amplitude.

Figure 1 shows sinusoidal waves emitted from source 1 100 and source 2 102. In the example shown in Figure 1, the waves from source 1 100 interfere with the waves emitted from source 2 102 according to the principle of superposition. This results in points of maximum intensity, such as point 104, and points of minimum intensity, such as point 106, where the waves from each source 100, 102 intersect. Points of maximum intensity 104 are those points at which the waves constructively interfere to produce a wave of increased amplitude. Points of minimum intensity 106 are those at which the waves destructively interfere to produce a wave of decreased amplitude. Points of minimum intensity 106 are represented in Figure 1 by circles and points of minimum intensity 106 are represented in Figure 1 by triangles.

Figure 1 shows the principle of uneven audio distribution of audio from adjacent audio sources 100, 102. Dependent on where a listener is stood, a different level of sound will be heard because of the different amplitudes of the waves. For example, a listener at point A will hear louder audio than a listener at point B because the listener at point A receives the constructively interfered waves, whereas the listener at point B receives the destructively interfered waves.

Figure 2 shows the interference of acoustic waves emitted from a first source 200 and a second source 202 when the waves are guided down adjacent waveguides 204, 206.

The waveguides 204, 206 prevent the acoustic waves from the two sources 200, 202 from interfering until they leave the openings of the waveguides 204, 206. In the example of Figure 2, the waveguides 204, 206 have parallel walls. This means that the waves 208, 210 travelling through the waveguides 204, 206 are substantially straight lines, in that they represent only a relatively short portion of the circular omnidirectional wave that is emitted from each source 200, 202. Therefore, as the waves reach the openings of the waveguides 204, 206, they interfere in a more constructive way, producing more evenly distributed audio, as shown by the substantially uniform waves 212. There is therefore a significant reduction, if not eradication, of points of maximum and minimum intensity.

Figures 3a-c show an exemplary loudspeaker horn arrangement 300 comprising three loudspeaker horns 301a-c. Each loudspeaker horn 301a-c comprises a first opening 304 at an inlet and a second opening 306 at an outlet. In the exemplary loudspeaker horn arrangement 300, the second opening 306 is substantially rectangular. A wall 308 connects the first and second openings 304, 306 and diverges towards the second opening 306. That is, the wall 308 is relatively narrow at the first opening 304 and broadens out towards the larger second opening 306.

The wall 308 comprises opposed upper and lower wall portions 308a, 308b. At least part of the opposed upper and lower wall portions 308a, 308b are substantially planar.

The upper and lower wall portions 308a, 308b form the top and bottom of the wall 308 of the speaker horn.

The angle between the planar regions of the opposed upper and lower wall portions 308a, 308b is less than 30 degrees. In other exemplary loudspeaker horns 300, the angle may be less than 25 degrees and may be substantially 20.8 degrees. The low angle between the opposed upper and lower wall portions 308a, 308b creates a situation similar to that shown in Figure 2, in which sidewall portions of waveguides are substantially parallel. The loudspeaker horns 301a-c therefore reduce the destructive interference between audio signals emitted from separate sources into each loudspeaker horn.

Although the loudspeaker horns 301a-c are shown in Figures 3a-c as being vertically aligned and formed into a single unit, it is noted that in exemplary apparatus the loudspeaker horns may be individually formed.

The second opening has a vertical height of at least half the wavelength of the lowest frequency audio signals to be transmitted therefrom. In exemplary apparatus, the second opening 306 may have a vertical height in a range from 10 cm to 15 cm and, in a particular exemplary apparatus the vertical height may be substantially 12.2 cm. The width of the second opening may be determined by the horizontal angle between vertical sidewall portions 308c, 308d. In exemplary loudspeaker horns, the horizontal angle may be 65 degrees or 90 degrees. In the example of Figures 3a-c, the horizontal angle is 65 degrees. In the example of Figures 4a-c, the horizontal angle is 90 degrees.

It is noted that relative terms, such as top, bottom, horizontal and vertical are used herein to aid description, but they need not be limiting on the scope of the apparatus disclosed herein.

The first opening 304 is configured to receive audio signals from an audio driver 309. The audio driver may be a compression driver, such as a B&C DE820TN, which has a substantially disc shaped body with a circular section having a radius of substantially 4.9 inches (12.45 cm). The size of the audio driver is, in some exemplary loudspeaker horn arrangements, a governing factor on the distance between first openings 304 of adjacent loudspeaker horns, as explained in more detail below with reference to Figures 4a-c. For example, in the exemplary loudspeaker horn arrangements 300 and 400 of figures 3a-c and 4a-c, the distance between first openings is approximately 12.5 cm.

An interconnecting edge 310 is formed by a lower edge of a second opening 306 of the first loudspeaker horn 301a and an upper edge of the second opening 306 of the second loudspeaker horn 301b. The interconnecting edge 310 substantially forms a vertex. The precision of the vertex may be restricted by manufacturing materials and processes. In exemplary loudspeaker horn arrangements 300, the vertex formed by the interconnecting edge 310 may be rounded and may have an internal radius of less than 5 mm and, in particular exemplary apparatus, the radius of the vertex may be substantially 2.5 mm. In other exemplary loudspeaker horn arrangements 300, the vertex formed by the interconnecting edge 310 may have a chamfered edge. The chamfered edge may have a vertical dimension in a range from 5 to 15 mm. In exemplary loudspeaker horn arrangements 300, it is desirable for the vertex formed by the interconnecting edge 310 to be as sharp as possible.

As a result of the horizontal angle between the opposed vertical wall portions 308c-d being 65 degrees, the maximum horizontal dimension of the second opening 306 is reached after around 27-29 cm. This is greater than in the loudspeaker horns 401a-b of Figures 4a-c. The angle between the opposed upper and lower wall portions 308a, 308b (in some apparatus fixed at a value of 20.8) and the distance between the first openings 304 (restricted to accommodate a particular audio driver) mean that the interconnecting edge 310 can be formed at a position flush with the second opening 306.

An internal angle 312 between adjacent loudspeaker horns 301a, 301b or 301b, 301c may be less than 30 degrees and, in particular exemplary apparatus, may be less than 25 degrees or substantially 20.8 degrees. In exemplary loudspeaker horn arrangements, centre lines 314a-c of adjacent loudspeaker horns 301a-c may converge in a direction towards the first openings 304. That is, the adjacent loudspeaker horns 301a-c may be rotated relative to one another such that the first openings 304 of each are closer together and the internal angle 312 is reduced. As shown in Figure 3b, the angle of relative rotation may be in a range from 0.1-1 degrees and in a specific exemplary apparatus may be substantially 0.3 degrees. Therefore, the internal angle 312 may be less than 29.7 degrees and, in specific exemplary apparatus, may be less than 24.7 or substantially 20.5 degrees. This may decrease further the destructive interference between audio emitted from separate sources into each of the adjacent loudspeaker horns 301a-c.

Outer edges 316a, 316b of the top horn 301a and bottom horn 301c may be rounded and have a radius of less than 10 mm and, in a specific apparatus, a radius of substantially 4 mm. Vertical edges 318a-b of each loudspeaker horn 301a-c are rounded with a radius in a range from 1-3 cm and, in a specific exemplary apparatus, a radius of 22 mm.

Figures 4a-c show a further exemplary loudspeaker horn arrangement 400 comprising two loudspeaker horns 401a-b arranged vertically adjacent. Many of the features of the loudspeaker horn arrangement 400 are similar to those described already in respect of the loudspeaker horn arrangement 300 and so they are not discussed in detail again here. Similar features have been given corresponding reference numerals starting with a "4" as opposed to a "3".

Each loudspeaker horn 401a-bc comprises a first opening 404 at an inlet and a second opening 406 at an outlet. A wall 408 comprises opposed upper and lower wall portions 408a-b at a relative angle of less than 30 degrees. In specific apparatus, the opposed upper and lower wall portions 408a-b of the loudspeaker horn 401a-b may have a relative angle of 25.2 degrees.

Respective upper and lower edges of the second openings 406 of adjacent loudspeaker horns 401a-b may abut to form an interconnecting edge 410. As in Figures 3a-c, the interconnecting edge 410 may be a vertex having a curved or a chamfered end.

An internal angle 412 between adjacent loudspeaker horns 401a-b may be less than 30 degrees or less than 26 degrees and, in a specific exemplary apparatus, may be 25.2 degrees. In exemplary loudspeaker horn arrangements, centre lines 414a-b of adjacent loudspeaker horns 401a-b may converge in a direction towards the first openings 404. That is, the adjacent loudspeaker horns 401a-b may be rotated relative to one another such that the first openings 404 of each are closer together and the internal angle 412 is reduced. As shown in Figure 4b, the angle of relative rotation between each loudspeaker horn 401a-b may be in a range from 2 degrees to 7 degrees and in a specific apparatus may be 5 degrees. Therefore, the internal angle 412 may be less than 26 degrees and in a specific apparatus may be substantially 20.2 degrees. This may decrease further the destructive interference between audio emitted from separate sources into each of the adjacent loudspeaker horns 401a-b.

The loudspeaker horn arrangements 300, 400 may be located within a speaker cabinet and have audio drivers attached thereto and configured to emit sound into each of the loudspeaker horns. Such an arrangement may form a loudspeaker. There may be one audio driver for each loudspeaker horn. A plurality of such loudspeakers may be arranged in a loudspeaker column.

The skilled person will appreciate that other embodiments are possible without departing from the scope of the appended claims.

Claims

CLAIMS: 1. A loudspeaker horn for high power music audio output, the horn comprising: a first opening at an inlet; a second opening at an outlet, wherein the second opening is substantially rectangular; a wall connecting the first and second openings, wherein the wall comprises opposed upper and lower wall portions that are divergent towards the second opening and at least a part of which are substantially planar, wherein an angle between the upper and lower wall portions is less than 30 degrees.
2. The loudspeaker horn of preceding claim 1, wherein the opposed planar upper and lower portions diverge towards the second opening at a relative angle in a range from 10 to 26 degrees.
3. The loudspeaker horn of claim 1 or 2, wherein a height of the second opening is in a range from 10 cm to 15 cm.
4. The loudspeaker horn of claim 3, wherein the height of the second opening is one of 12.2 cm and 10.95 cm.
5. The loudspeaker horn of any preceding claim, wherein the height of the second opening is at least half the wavelength of the lowest frequency sound waves of the audio output.
6. The loudspeaker horn of claim 5, wherein the lowest frequency sound waves are substantially 4 kHz.
7. The loudspeaker horn of any preceding claim, wherein a vertical edge of the second opening is rounded.
8. The loudspeaker horn any preceding claim, wherein a distance from the first opening to the second opening is in a range from 15cm to 30cm.
9. The loudspeaker horn of any preceding claim, wherein the first opening at the inlet of the horn is substantially circular.
10. A loudspeaker horn arrangement comprising a plurality of adjacent loudspeaker horns of any preceding claim.
11. The loudspeaker horn arrangement of claim 10, wherein the plurality of loudspeaker horns are vertically aligned.
12. A loudspeaker horn arrangement according to claim 11, wherein an upper horizontal edge of a second opening of a first loudspeaker horn is adjacent a lower horizontal edge of a second opening of a second loudspeaker horn.
13. The loudspeaker horn arrangement of claim 11 or 12, wherein the adjacent upper and lower horizontal edges abut to form an interconnecting edge.
14. The loudspeaker horn arrangement of claim 13, wherein the interconnecting edge substantially forms a vertex.
15. The loudspeaker horn arrangement of claim 13, wherein the vertex is rounded at a radius of less than 5mm.
16. The loudspeaker horn arrangement of any of claims 10 to 15, wherein an internal angle between adjacent loudspeaker horns is less than 25°. 25
17. The loudspeaker horn arrangement of claim 16, wherein the internal angle between adjacent loudspeaker horns is in a range from 20 to 21 degrees.
18. The loudspeaker horn arrangement of any of claims 10 to 17, wherein central axes of adjacent loudspeaker horns converge in a direction towards the first openings.
19. The loudspeaker horn arrangement of claim 18, wherein the relative angle between central axes of adjacent loudspeaker horns is in a range from 0.1° to 60.
20. The loudspeaker horn arrangement of any of claims 10 to 19, wherein a distance between the first openings of adjacent loudspeaker horns is at least 10 cm.
21. The loudspeaker horn arrangement of any of claims 10 to 20, wherein a distance between the first openings of adjacent loudspeaker horns is substantially 12.5 cm.
22. The loudspeaker horn arrangement of any of claims 10 to 21, wherein the interconnecting edge protrudes from a plane of the second openings of the adjacent loudspeaker horns.
23. The loudspeaker horn arrangement of claim 22, wherein the wall comprises opposed vertical wall portions divergent towards the second opening, wherein an angle between the horizontally opposed substantially planar sidewall portions is substantially 90 degrees.
24. The loudspeaker horn arrangement of any of claims 22 to 23, comprising two adjacent loudspeaker horns only.
25. The loudspeaker horn arrangement of any of claims 10 to 19, wherein the sidewall comprises opposed vertical wall portions divergent towards the second opening, wherein an angle between the horizontally opposed substantially planar sidewall portions is substantially 65 degrees.
26. The loudspeaker horn arrangement of claim 25, comprising three adjacent loudspeaker horns.
27. A loudspeaker arrangement comprising a loudspeaker horn arrangement according to any of claims 10 to 26 and a plurality of audio drivers, each audio driver configured to emit audio into a loudspeaker horn of the loudspeaker horn arrangement.
28. A column of loudspeakers comprising a loudspeaker arrangement according to claim 27.
29. A loudspeaker horn substantially as herein described with reference to the accompanying drawings.
30. A loudspeaker horn arrangement substantially as herein described with reference to the accompanying drawings.