Omni-directional speaker with asymmetric vertical directivity

Abstract

A compression driver for an omnidirectional loudspeaker includes a motor assembly and a ring diaphragm coaxially disposed below and operably connected to the motor assembly. A phase plug is mounted to the motor assembly and includes a top portion facing the diaphragm, a bottom portion extending downward from the top portion from a first end to a second end, and a plurality of apertures extending through the phase plug. The bottom portion has an inner surface defining a cavity and widening from the first end to the second end, the inner surface having a plurality of radial channels having a diagonal orientation acoustically connected to the apertures. A housing is mounted to the phase plug and received within the cavity, the housing having an outer surface spaced apart from the inner surface of the bottom portion to form a waveguide arranged to radiate sound waves downward and outward in an asymmetric vertical directivity.

Description

Technical Field

[0001] The implementation scheme involves an omnidirectional loudspeaker with asymmetric vertical orientation, and a compression driver and waveguide used in the omnidirectional loudspeaker. Background Technology

[0002] Omnidirectional loudspeakers radiate sound in all directions. Current designs of ceiling omnidirectional loudspeakers, suspended omnidirectional loudspeakers, and column omnidirectional loudspeakers include direct-radiating transducers with conical or dome diaphragms that have corresponding "diffusers" that diffuse sound waves in an omnidirectional manner. The transducer is oriented vertically with the diaphragm axis aligned, such that the sound radiation is converted into a distribution in the horizontal plane. Unfortunately, direct-radiating transducers are inefficient, at most only a few percent. This limits the efficiency, sensitivity, and maximum sound pressure level (SPL) of transducers and loudspeaker systems that provide omnidirectional radiation. Furthermore, in ceiling or suspended loudspeakers, the sound radiation is typically distributed symmetrically in the vertical plane, but radiation in the upper vertical hemisphere is unwanted or undesirable. Summary of the Invention

[0003] In one or more embodiments, a compression driver for an omnidirectional loudspeaker includes: a motor assembly disposed about a central axis; and an annular diaphragm coaxially disposed below and operatively connected to the motor assembly. A phase-modulation plug is mounted to the motor assembly and includes a top portion facing the diaphragm and defining a compression chamber between the diaphragm and the top portion. The phase-modulation plug includes a bottom portion extending downward from the top portion along the central axis from a first end to a second end, the bottom portion including a plurality of orifices extending therethrough. The bottom portion has an inner surface defining a cavity and widening from the first end to the second end, the inner surface having a plurality of radial channels having a diagonal orientation acoustically connected to the orifices. A housing is mounted to the phase-modulation plug along the central axis and received within the cavity, the housing having an outer surface spaced apart from the inner surface of the bottom portion to form a waveguide, the waveguide being arranged to radiate sound waves asymmetrically vertically downward and outward.

[0004] In one or more embodiments, a waveguide for an omnidirectional loudspeaker includes a phase-modulation plug comprising a top portion and a bottom portion extending downward along a central axis from a first end to a second end. The phase-modulation plug includes a plurality of orifices extending therethrough, and the bottom portion has an inner surface defining a cavity and widening from the first end to the second end, the inner surface having a plurality of radial channels having a diagonal orientation acoustically connected to the orifices. A housing is mounted to the phase-modulation plug along the central axis and received within the cavity, the housing having an outer surface spaced apart from the inner surface of the bottom portion to form an annular passage arranged to radiate sound waves asymmetrically vertically downward and outward.

[0005] In one or more embodiments, an omnidirectional loudspeaker includes a compression driver having: a motor assembly disposed about a central axis; and an annular diaphragm coaxially disposed below and operatively connected to the motor assembly. A phase-modulating plug is mounted to the motor assembly and includes a top portion facing the diaphragm and defining a compression chamber between the diaphragm and the top portion. The phase-modulating plug includes a bottom portion extending downward from the top portion along the central axis from a first end to a second end, the bottom portion including a plurality of orifices extending therethrough. The bottom portion has an inner surface defining a cavity and widening from the first end to the second end, the inner surface having a plurality of radial channels having a diagonal orientation acoustically connected to the orifices. A housing is mounted to the phase-modulating plug along the central axis and received within the cavity, the housing having an outer surface spaced apart from the inner surface of the bottom portion to form a waveguide, the waveguide being arranged to radiate sound waves downward and outward. The horn is mounted to the compression driver along the central axis so as to propagate the sound waves in an asymmetrical vertical direction. Attached Figure Description

[0006] Figure 1 It is an exploded perspective view of a compression driver used in an omnidirectional loudspeaker with asymmetric vertical orientation, according to one or more embodiments;

[0007] Figure 2 yes Figure 1 A cross-sectional view of the assembled compression drive;

[0008] Figure 3 yes Figure 1 A bottom perspective view of the assembled compressor drive;

[0009] Figure 4It is a top view of the phase-shifting plug of a compression driver according to one or more embodiments;

[0010] Figure 5 yes Figure 4 A bottom view of the phase-shifting plug;

[0011] Figure 6A and Figure 6B These are symmetric omnidirectional actuators and Figures 1 to 3 A schematic diagram of the directionality of an asymmetric omnidirectional actuator in the vertical plane;

[0012] Figure 7 It includes, according to one or more implementation schemes. Figures 1 to 5 A cross-sectional view of an omnidirectional loudspeaker with asymmetric vertical orientation, consisting of a compression driver and an attached horn.

[0013] Figure 8 It is based on another implementation scheme including Figures 1 to 5 A cross-sectional view of an omnidirectional loudspeaker with asymmetric vertical orientation, consisting of a compression driver and an attached horn.

[0014] Figure 9 This is a top view of the phase-shifting plug of a compression drive according to another embodiment; and

[0015] Figure 10 yes Figure 9 A bottom view of the phase-adjusting plug. Detailed Implementation

[0016] As requested, detailed embodiments of the invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely examples of the invention that may be embodied in various alternative forms. The drawings are not necessarily drawn to scale; some features may be enlarged or minimized to show details of specific components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching those skilled in the art to apply the invention in different ways.

[0017] The embodiments disclosed herein include an omnidirectional loudspeaker that provides omnidirectional directivity in the horizontal plane while also providing asymmetric vertical directivity. Utilizing a compression driver, high efficiency and sensitivity, as well as lower distortion, are thus provided compared to direct-radiating loudspeakers used for the same SPL. Furthermore, the phase-modulating plug and waveguide configuration disclosed herein allows sound to be radiated both downwards and outwards simultaneously, while naturally blending into the corresponding outward- and downward-radiating loudspeakers to provide optimized SPL coverage.

[0018] First refer to Figures 1 to 5The diagram illustrates a compression driver 100, comprising a motor assembly 102, an annular curved diaphragm 104 disposed below and operatively connected to the motor assembly 102, a phase-shifting plug 106 mounted to the motor assembly 102, and a housing 108 mounted to the phase-shifting plug 106, all components being coaxial along a central axis 110. In one or more embodiments, the motor assembly 102 may include an annular permanent magnet 112 disposed between an annular top plate 114 and a back plate 116, the back plate comprising centrally located cylindrical or annular pole pieces 118, but the motor assembly 102 is not limited to this configuration. As is known in the art, the motor assembly 102 provides a permanent magnetic field for electro-coupled with a voice coil (not shown), wherein the voice coil is mechanically coupled to the diaphragm 104 and produces movement of a flexible portion of the diaphragm 104 to convert received electrical signals into sound waves. The motor assembly 102, diaphragm 104, phase-shifting plug 106, and housing 108 may be joined together by fasteners or adhesives.

[0019] There are two main types of compression drivers: the first utilizes a dome diaphragm, and the other uses a toroidal curved diaphragm 104 as disclosed herein. One advantage of the toroidal diaphragm is that the radial dimension of the moving portion of the diaphragm is smaller compared to a dome diaphragm with the same moving voice coil diameter. In the compression driver, the diaphragm 104 consists of a compression chamber 120 (… Figure 2 The compression chamber 104 is a thin layer of air separating the diaphragm 104 from the phase-tuning plug 106. The volume of air trapped in the compression chamber 120 is characterized by acoustic compliance proportional to the volume of the compression chamber 120. In practice, the height of the compression chamber 120 can be very small (e.g., about 0.5 mm or less), resulting in a small volume of the compression chamber 120. The small radial dimension of the annular diaphragm 104 corresponds to the small radial dimension of the matching compression chamber 120, which shifts undesirable air resonances (cross modes) within the chamber to higher frequencies, sometimes above the audio range. Because the annular diaphragm 104 has two clamping peripheries, one inside and one outside the moving portion of the diaphragm 104, it has better dynamic stability and is less prone to swing modes compared to a dome diaphragm with only external clamping. The diaphragm 104 may include irregularly shaped segments such as V-shaped segments 122, or may have other suitable configurations.

[0020] As background, Figure 6A A schematic diagram of the directional pattern of a typical symmetrical omnidirectional loudspeaker in a vertical plane is shown. At low frequencies, the loudspeaker is virtually omnidirectional in the vertical plane. However, as the frequency increases, the upward and downward radiation attenuates, as indicated by the arrows. There are many applications that require vertical asymmetric radiation, such as ceiling loudspeakers or suspended loudspeakers. For such systems, radiation in the upper vertical hemisphere is undesirable or unwanted. Figure 6BA schematic diagram of the directional pattern of an asymmetric omnidirectional loudspeaker in a vertical plane, as disclosed herein, is shown. The directional pattern is the desired directional pattern of a ceiling loudspeaker or a suspended loudspeaker in a vertical plane.

[0021] exist Figure 6B In the scenario illustrated, sound energy is primarily directed downwards and laterally, as indicated by the arrows, thus providing acoustic illumination beneath the speaker covering a specific area. Ideally, the directional response beneath the speaker should compensate for the attenuation of the directional response with distance in the horizontal plane (at the listener's level) as the listener moves away from the stilted or ceiling speaker. For example, for a typical ceiling or stilted speaker with a 140-degree coverage area (corresponding to a -6 dB attenuation in the polarity response), the attenuation corresponding to the projected listening plane beneath the speaker is approximately -15 dB. Therefore, the directional pattern should compensate for the additional attenuation caused by the change from polarity directivity requirements to listening plane directivity.

[0022] To compensate for additional attenuation in the listening plane, the phase-modulating plug 106 disclosed herein includes a top portion 124 and a bottom portion 126 extending downward from the top portion 124 along a central axis 110, as follows: Figure 1 and Figures 4 to 5 As best shown. The top portion 124 includes a top side 128 facing the diaphragm 104, wherein the compression chamber 120 is defined in the space between the diaphragm 104 and the top side 128. The top portion 124 may be integrally formed with the bottom portion 126, or may be attached to the bottom portion 126 by any suitable means. The top portion 124 of the phase-shifting plug 106 may be generally circular or may have any other suitable geometry. The top portion 124 may be coupled to or mounted to the backplate 116 of the motor assembly 102.

[0023] refer to Figure 2 and Figure 4 The phase-shifting plug 106 may include a mounting member 130 located on a top portion 124, the mounting member abutting upward from a top side 128. The mounting member 130 may have any configuration suitable for coupling the phase-shifting plug 106 to a motor assembly 102 or to the rear of a compression driver 100. In one embodiment, the mounting member 130 may be provided in a cylindrical form, the cylinder being arranged to press-fit into a recess 132 formed in an electrode plate 118. The phase-shifting plug 106 may also include a central hole 134 for coupling or mounting the phase-shifting plug 106 to a back plate 116 of the motor assembly 102 via a fastener (not shown).

[0024] like Figures 1 to 3As shown, the bottom portion 126 has a first end 136 disposed near the top portion 124 and a second end 138 disposed at a certain distance from the top portion 124. The outer surface 140 of the bottom portion 126 may be generally cylindrical, while the inner surface 142 of the bottom portion 126 may widen relative to the central axis 110 from the first end 136 to the second end 138. Therefore, the inner surface 142 may be generally truncated conical in shape and define a cavity 144, wherein the radius from the central axis 110 to the inner surface 142 increases from the first end 136 to the second end 138.

[0025] like Figures 1 to 2 and Figures 4 to 5 As shown, the phasing plug 106 includes a plurality of orifices 146 extending from the top portion 124 through the phasing plug 106 to the bottom portion 126, through which acoustic energy generated by the diaphragm 104 can propagate. For each orifice 146, the area of ​​the inlet of the phasing plug 106 is significantly smaller than the area of ​​the diaphragm 104. In the embodiment depicted herein, the orifices 146 may be arranged generally circumferentially around a central axis 110, forming a generally circular shape. However, the orifices 146 are not limited to the embodiment depicted herein and may include other suitable shapes and configurations. For example, in… Figure 9 and Figure 10 In an alternative embodiment depicted, orifice 146 may be an end-to-end positioned diagonal slot, such as arranged generally circumferentially around central axis 110 in a zigzag or sawtooth pattern. This zigzag distribution of orifice 146 may have the effect of eliminating air resonance in compression chamber 120 in order to shape and improve the wavefront exiting compression actuator 100.

[0026] In one or more embodiments, the inner surface 142 of the bottom portion 126 may have a central section 148 and a plurality of arms 150 extending downward and outward from said central section, such as Figure 1 and Figure 5 As best shown. The aperture 146 may be disposed or formed along the edge 152 of the central section 148, wherein an arm 150 extends between each pair of adjacent apertures 146. In other words, the arm 150 may be disposed on each side of the aperture 146. From a bottom view (see...) Figure 5 It is evident that each arm 150 may be generally triangular in shape. For this triangular shape, the arm 150 is widest at its edge 152 near the central segment 148, and its width gradually tapers towards the second end 138 of the bottom portion 126. It should be understood, of course, that the phase-shifting plug 106 is not limited to the embodiments depicted herein, and that the top portion 124 and the bottom portion 126 may include other suitable shapes and configurations. For example, in an alternative embodiment, each arm 150 may have a thin-walled configuration with a generally constant width.

[0027] Therefore, each orifice 146 is acoustically connected to a corresponding radial channel 154 defined between each pair of adjacent arms 150. The radial channel 154 may have an extended width and converge at a second end 138 of the bottom portion 126. The channel 154 can be used to ensure a uniform distribution of sound pressure around the entire compression driver 100 to achieve omnidirectional radiation of sound in the horizontal plane. Advantageously, the diagonal orientation of the radial channel 154 in the phase-modulation plug 106 simultaneously directs the acoustic signal outward and downward. In addition to the embodiments depicted herein, it is contemplated that the phase-modulation plug 106 may include fewer or more orifices 146 or channels 154, or alternatively may be configured without radially extended channels 154.

[0028] refer to Figures 1 to 3 The housing 108 is received within the cavity 144 and attached to the bottom portion 126 of the phase-modulation plug 106. The housing 108 has a top end 156 disposed on or attached to the phase-modulation plug 106 (e.g., at the central section 148 of the bottom portion 126) and a bottom end 158 disposed at a distance from the bottom portion 126. The housing 108 may include a downwardly extending boss 160 having a central hole 162 for mounting the housing 108 to the bottom portion 126 and the motor assembly 102 via fasteners (not shown). As shown, the housing 108 may be generally truncated conical in shape, wherein the outer surface 164 of the housing 108 may have a generally straight, smooth profile from the top end 156 to the bottom end 158. When assembled, the bottom portion 126 of the phase-modulation plug 106 and the housing 108 together form a waveguide 166. More specifically, the inner surface 142 of the bottom portion 126 and the outer surface 164 of the housing 108 cooperate to form a waveguide 166 and annular outlet 168 of the compression driver 100, providing a generally annular path for the propagation of sound waves from the orifice 146 to the annular outlet 168. The waveguide 166 can be used to control the directionality of sound waves propagating from the compression driver 100 into the surrounding environment (i.e., the coverage of sound pressure over a specific listening area) and to increase the reproducible SPL within a specific frequency range.

[0029] refer to Figure 7 and Figure 8 A cross-sectional view of an omnidirectional loudspeaker 300, including a compression driver 100 and an attached horn 200, is shown according to one or more embodiments. The compression driver 100 and the horn 200 are arranged substantially symmetrically about a central axis 110. Figure 7 and Figure 8As shown, the horn 200 may include one or more walls 202 surrounding the interior 204 of the horn 200. The horn walls 202 may widen outwardly from the central axis 110 to provide an expanded cross-sectional area through which sound waves propagate. The horn walls 202 form an inlet 206 or throat (adjacent to the bottom 126 of the phase plug 106) and an outlet 208 (also referred to as the flare). The horn 200 includes suitable construction for mounting to the compression driver 100 via fasteners or adhesives (such as via the boss 160 and central hole 162 of the housing 108). The phase plug 106, housing 108, and waveguide 166 are formed as disclosed herein to provide a smooth transition to the axially symmetric horn 200 in a corresponding orientation, which provides uniform coverage of the listening area below the speaker.

[0030] In operation, the actuation of the diaphragm 104 by the motor assembly 102 generates a high-pressure acoustic signal within the compression chamber 120, and the high-pressure acoustic signal propagates as a sound wave through the top portion 124 and bottom portion 126 of the phase plug 106 via the aperture 146. Then, the acoustic signal passes through the radial channel 154 within the waveguide 166 formed by the bottom portion 126 and the outer surface 164 of the housing 108 and exits from the annular outlet 168. The sound wave enters through the attached horn inlet 206 and radiates through the interior 204 of the horn 200 and propagates from the horn outlet 208 into the surrounding environment. The total acoustic cross-sectional area of the air path including the aperture 146 and the outwardly radiating channel 154 gradually increases to provide a smooth transition of the sound wave.

[0031] Figure 7 and Figure 8 An example of the assembly of the compression driver 100 and the horn 200 is shown, having different coverage ranges in a vertical plane and different SPL ratios below and at a certain distance from the speaker 300. Figure 7 The configuration provides a "longer throw", i.e., the SPL difference below the speaker 300 and at a certain distance from the speaker 300 is greater than Figure 8 the SPL difference in the version shown. The arrows in each figure indicate the orientation of the radiation direction of the horn 200. A tweeter (not shown) may be provided in the Figure 7 smaller horn 210. Figure 7 and Figure 8 The horn 200 depicted in and is merely exemplary, and other configurations are fully conceivable.

[0032] It should be understood that directional identifiers such as top, bottom, above, below, upper, lower, upward, and downward used herein are not intended to be limiting, but are merely used to provide an exemplary context for the components of the compression driver 100, horn 200, and omnidirectional speaker 300 as disclosed herein. Any directional terms used herein are used only to indicate the relative arrangement of the various components of the compression driver 100, horn 200, and omnidirectional speaker 300, and are not intended to be limiting.

[0033] The applications of the compression driver 100 and omnidirectional speaker 300 described herein include, but are not limited to, landscape sound systems, home loudspeaker systems, public address systems, alarm and warning sound systems, Bluetooth-based portable audio loudspeakers, high-power pendant loudspeakers, negative-directivity ceiling loudspeakers, or other applications where omnidirectionality in the horizontal plane and asymmetric vertical directionality are desired or required. The use of the compression driver 100 in the omnidirectional speaker 300 disclosed herein results in a tenfold increase in efficiency and sensitivity, as well as an increase in maximum sound pressure level, compared to a direct-radiating dome loudspeaker.

[0034] While exemplary embodiments have been described above, they do not imply that these embodiments describe all possible forms of the invention. In fact, the wording used in this specification is descriptive rather than limiting, and it should be understood that various changes can be made without departing from the spirit and scope of the invention. Furthermore, features of various implementation embodiments can be combined to form other embodiments of the invention.

Claims

1. A compression driver for an omnidirectional loudspeaker, the compression driver comprising: A motor assembly, wherein the motor assembly is arranged around a central axis; A ring diaphragm, the ring diaphragm being coaxially disposed below the motor assembly and operably connected to the motor assembly; A phasing plug is mounted to the motor assembly and includes a top portion facing the diaphragm and defining a compression chamber between the diaphragm and the top portion. The phasing plug includes a bottom portion extending downward from the top portion along the central axis from a first end to a second end. The phasing plug includes a plurality of orifices extending therethrough. The bottom portion has an inner surface defining a cavity and widening from the first end to the second end. The inner surface has a plurality of radial channels having a diagonal orientation acoustically connected to the orifices. as well as A housing, which is mounted to the phase-tuning plug along the central axis and received within the cavity, has an outer surface spaced apart from the inner surface of the bottom portion to form a waveguide, the waveguide being arranged to radiate sound waves asymmetrically vertically downward and outward.

2. The compression driver of claim 1, wherein the plurality of radial channels have an extended width and converge at the second end of the bottom portion.

3. The compression actuator of claim 1, wherein the plurality of orifices are arranged generally circumferentially around the central axis.

4. The compression actuator of claim 1, wherein the inner surface of the bottom portion has a central segment and a plurality of arms extending downward and outward from the central segment, wherein a pair of adjacent arms defines one of the plurality of radial channels therebetween, wherein one of the plurality of arms extends between each pair of adjacent orifices.

5. The compression drive of claim 4, wherein each of the plurality of arms is generally triangular in shape and is widest at the edge adjacent to the central section and tapers in width toward the second end of the bottom portion.

6. The compression driver of claim 1, wherein the inner surface of the bottom portion has a truncated conical shape, wherein the radius from the central axis to the inner surface increases from the first end to the second end.

7. The compression actuator of claim 1, wherein the housing is generally truncated conical in shape, and wherein the outer surface has a generally straight, smooth profile from top to bottom.

8. A waveguide for an omnidirectional loudspeaker, the waveguide comprising: A phase-shifting plug, the phase-shifting plug including a top portion and a bottom portion, the bottom portion extending downward along a central axis from a first end to a second end from the top portion, the phase-shifting plug including a plurality of orifices extending therethrough, the bottom portion having an inner surface defining a cavity and widening from the first end to the second end, the inner surface having a plurality of radial channels having a diagonal orientation acoustically connected to the orifices; as well as A housing, which is mounted to the phase-shifting plug along the central axis and received within the cavity, the housing having an outer surface spaced apart from the inner surface of the bottom portion to form an annular passage, the annular passage being arranged to radiate sound waves asymmetrically vertically downward and outward.

9. The waveguide of claim 8, wherein the plurality of radial channels have an extended width and converge at the second end of the bottom portion.

10. The waveguide of claim 8, wherein the plurality of apertures are arranged generally circumferentially around the central axis.

11. The waveguide of claim 8, wherein the inner surface of the bottom portion has a central segment and a plurality of arms extending downward and outward from the central segment, wherein a pair of adjacent arms defines one of the plurality of radial channels therebetween, wherein one of the plurality of arms extends between each pair of adjacent apertures.

12. The waveguide of claim 11, wherein each of the plurality of arms is generally triangular in shape and is widest at the edge adjacent to the central segment and tapers in width toward the second end of the bottom portion.

13. The waveguide of claim 8, wherein the inner surface of the bottom portion has a truncated conical shape, wherein the radius from the central axis to the inner surface increases from the first end to the second end.

14. The waveguide of claim 8, wherein the housing is generally truncated conical in shape, and wherein the outer surface has a generally straight, smooth profile from top to bottom.

15. An omnidirectional loudspeaker, comprising: A compression driver, the compression driver comprising: A motor assembly, wherein the motor assembly is arranged around a central axis; A ring diaphragm, the ring diaphragm being coaxially disposed below the motor assembly and operably connected to the motor assembly; A phase-shifting plug, mounted to the motor assembly and including a top portion facing the diaphragm and defining a compression chamber between the diaphragm and the top portion, the phase-shifting plug including a bottom portion extending downward from the top portion along the central axis from a first end to a second end, the phase-shifting plug including a plurality of orifices extending therethrough, the bottom portion having an inner surface defining a cavity and widening from the first end to the second end, the inner surface having a plurality of radial channels having a diagonal orientation acoustically connected to the orifices; and A housing, mounted along the central axis to the phase-tuning plug and received within the cavity, the housing having an outer surface spaced apart from the inner surface of the bottom portion to form a waveguide, the waveguide being arranged to radiate acoustic waves downwards and outwards; and A horn, which is mounted to the compression driver along the central axis, so as to propagate the sound waves in an asymmetrical vertical direction.

16. The omnidirectional loudspeaker of claim 15, wherein the plurality of radial channels have an extended width and converge at the second end of the bottom portion.

17. The omnidirectional loudspeaker of claim 15, wherein the plurality of apertures are arranged generally circumferentially around the central axis.

18. The omnidirectional loudspeaker of claim 15, wherein the inner surface of the bottom portion has a central section and a plurality of arms extending downward and outward from the central section, wherein a pair of adjacent arms defines one of the plurality of radial channels therebetween, wherein one of the plurality of arms extends between each pair of adjacent apertures.

19. The omnidirectional loudspeaker of claim 18, wherein each of the plurality of arms is generally triangular in shape and is widest at the edge adjacent to the central section and tapers in width toward the second end of the bottom portion.

20. The omnidirectional loudspeaker of claim 15, wherein the housing is generally truncated conical in shape, and wherein the outer surface has a generally straight, smooth profile from top to bottom.

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