Dual compression driver with annular outlet

Abstract

A dual compression driver includes a first driver assembly and a second driver assembly, the first driver assembly and the second driver assembly each including: a motor assembly disposed about a central axis; the annular diaphragm is coaxial with each motor assembly and is operably connected to each motor assembly; and a phase plug which is coaxial with each diaphragm. Each phase plug includes an input side oriented toward the diaphragm, an output side oriented away from the diaphragm, and a plurality of apertures therethrough. A hollow extension conduit has a bottom end mounted to a phase plug of the first driver assembly, with an inner surface of the extension conduit and an outer surface of the second driver assembly forming an annular passage that terminates at an annular outlet of the dual compression driver. Acoustic signals from the first driver assembly and the second driver assembly merge between the output sides of the phase plugs and radiate radially outward to the annular passage and through the annular outlet.

Description

Technical Field

[0001] The embodiments relate to a dual compression driver having an annular outlet leading to a waveguide or a horn. Background Art

[0002] The dual compression driver includes two annular diaphragms, where the diaphragms either have the same profile and operate in the same frequency range or have different profiles and radiate in different frequency bands. In addition to the two diaphragms, the dual compression driver also includes two motor assemblies and two phase plugs. The phase plugs are positioned facing each other, and the diaphragms radiate through two acoustic chambers having mutual acoustic loads (waveguide or horn).

[0003] Comparing the dual compression driver with a conventional driver having a dome diaphragm and a voice coil of the same diameter, the moving mass of each diaphragm in the dual compression driver is lower because the mass is distributed between the two diaphragms. Advantageously, the lower moving mass extends the high-frequency range of the dual compression driver. Using two voice coils instead of one voice coil reduces thermal compression and increases the dynamic range and the maximum SPL (Sound Pressure Level) because the same level of output acoustic signal can be achieved with smaller displacements of each voice coil and each diaphragm. For the same reason, the low-frequency distortion of the dual compression driver is also smaller compared to the conventional driver.

[0004] Existing dual compression drivers utilize a circular outlet. The diameter of the outlet is related to the cross-mode excited at the entrance of the corresponding horn or waveguide and the directivity control at high frequencies. In a constant directivity waveguide, when the driver outlet diameter (equal to the waveguide or horn inlet diameter) is comparable to the wavelength of the radiated signal, the directivity control is lost. The same effect has also been observed in waveguides used in line arrays, where a larger outlet diameter deteriorates the high-frequency directivity control.

[0005] In a line array, the inlet of the waveguide is typically circular, while the outlet of the waveguide is typically rectangular, with a vertical dimension significantly larger than the horizontal dimension. For this reason, wide directivity is provided in the horizontal plane, and narrow directivity is provided in the vertical plane. The goal of the waveguide in a line array is to transform the circular inlet into a rectangular outlet and provide a "flat" wavefront in the vertical plane. When several line arrays are stacked vertically and a single or several waveguides form a very long vertically directed radiator, a cylindrical wave rather than a spherical wave is generated. This is achieved via a progressive time delay of the sound waves towards the middle of the vertically directed outlet such that the arrival time of the sound waves is equal along the vertical profile of the waveguide. In a driver having a circular outlet and a corresponding circular inlet of the waveguide, the acoustic path has to narrow to reach the outlet of the driver and then starts widening again in the waveguide, resulting in unnecessary redundancy. Summary of the Invention

[0006] In one or more embodiments, a dual compression driver includes a first driver assembly that includes: a first motor assembly disposed about a central axis at a first end of the dual compression driver; a first annular diaphragm coaxially disposed above the first motor assembly and operably connected to the first motor assembly; and a first phase plug coaxially disposed above the first annular diaphragm, the first phase plug including an input side oriented toward the first annular diaphragm and an output side oriented away from the first annular diaphragm, the first phase plug including a first plurality of holes therethrough. A second driver assembly includes: a second motor assembly disposed about the central axis at a second end of the dual compression driver; a second annular diaphragm coaxially disposed below the second motor assembly and operably connected to the second motor assembly; and a second phase plug coaxially disposed below the second annular diaphragm, the second phase plug including an input side oriented toward the second annular diaphragm and an output side oriented away from the second annular diaphragm, the second phase plug including a second plurality of holes therethrough. A hollow extension duct has a bottom end mounted to the first phase plug and a top end extending toward the second end of the dual compression driver, wherein an inner surface of the extension duct and an outer surface of the second driver assembly form an annular passage that terminates at an annular outlet at the second end of the dual compression driver. Acoustic signals from the first plurality of holes are combined with acoustic signals from the second plurality of holes between the output side of the first phase plug and the output side of the second phase plug, and radiate radially outward into the annular passage and through the annular outlet.

[0007] In one or more embodiments, the second driver assembly includes a housing mounted at the second end of the dual compression driver, a side surface of the housing forming at least a portion of the annular passage. In one or more embodiments, the diameter of the first phase plug is greater than the diameter of the second phase plug.

[0008] In one or more embodiments, the extension duct is generally cylindrical. In one or more embodiments, the inner surface of the extension duct includes a plurality of spaced-apart members that define acoustic channels therebetween. In one or more embodiments, each of the plurality of spaced-apart members is wider at the bottom end of the extension duct than at the top end thereof, such that the acoustic channels expand from the bottom end of the extension duct to the top end of the extension duct.

[0009] In one or more embodiments, the first motor assembly includes a first annular magnet, and the second motor assembly includes a second annular magnet. In one or more embodiments, the first plurality of holes and the second plurality of holes are each circumferentially arranged generally around the central axis. In one or more embodiments, the first plurality of holes and the second plurality of holes each have a zigzag configuration around the central axis.

[0010] In one or more embodiments, the output side of the first phase plug includes a first plurality of radial channels extending outwardly from the first plurality of holes, and the output side of the second phase plug includes a second plurality of radial channels extending outwardly from the second plurality of holes, the first plurality of radial channels and the second plurality of radial channels forming a part of a shared acoustic path for directing the combined acoustic signal to the annular passage. In one or more embodiments, the width of the first plurality of radial channels expands from the first plurality of holes toward the outer edge of the first phase plug, and the width of the second plurality of radial channels expands from the second plurality of holes toward the outer edge of the second phase plug.

[0011] In one or more embodiments, the first phase plug includes: a first base and a first mounting portion, the first mounting portion extending downwardly from the first base on the input side of the first phase plug for mounting to the first motor assembly; and the second phase plug includes a second base and a second mounting portion, the second mounting portion extending upwardly from the second base on the input side of the second phase plug for mounting to the second motor assembly.

[0012] In one or more embodiments, a first compression chamber is defined between the input side of the first phase plug and the first annular diaphragm, and a second compression chamber is defined between the input side of the second phase plug and the second annular diaphragm, the first plurality of holes forming an outlet leading to the first compression chamber, and the second plurality of holes forming an outlet leading to the second compression chamber.

[0013] In one or more embodiments, a dual compression driver includes a first driver assembly that includes: a first motor assembly disposed about a central axis at a first end of the dual compression driver; a first annular diaphragm coaxially disposed above the first motor assembly and operatively connected to the first motor assembly; and a first phase plug coaxially disposed above the first annular diaphragm, the first phase plug including an input side oriented toward the first annular diaphragm and an output side oriented away from the first annular diaphragm, the first phase plug including a first plurality of holes therethrough. A second driver assembly includes: a second motor assembly disposed about the central axis at a second end of the dual compression driver; a second annular diaphragm coaxially disposed below the second motor assembly and operatively connected to the second motor assembly; and a second phase plug coaxially disposed below the second annular diaphragm, the second phase plug including an input side oriented toward the second annular diaphragm and an output side oriented away from the second annular diaphragm, the second phase plug including a second plurality of holes therethrough. A bottom end of a hollow extension duct is mounted to the first phase plug, and its top end extends toward the second end of the dual compression driver. A housing is mounted to the second driver assembly at the second end of the dual compression driver, wherein an inner surface of the extension duct and an outer surface of the housing form an annular passage that terminates at an annular outlet at the second end of the dual compression driver. Acoustic signals from the first plurality of holes and acoustic signals from the second plurality of holes are combined between the output side of the first phase plug and the output side of the second phase plug and radiate radially outward into the annular passage and through the annular outlet.

[0014] In one or more embodiments, the extension duct has a generally frustoconical shape with its width expanding from the bottom end of the extension duct to the top end of the extension duct, and the housing substantially encloses the second driver assembly, wherein the top end of the housing is wider than the bottom end of the housing.

[0015] In one or more embodiments, the transducer includes a dual compression driver and a waveguide. The dual compression driver includes a first driver assembly that includes: a first motor assembly disposed about a central axis at a first end of the dual compression driver; a first annular diaphragm coaxially disposed above the first motor assembly and operatively connected to the first motor assembly; and a first phase plug coaxially mounted to the first motor assembly above the first annular diaphragm, the first phase plug including an input side oriented toward the first annular diaphragm and an output side oriented away from the first annular diaphragm, the first phase plug including a first plurality of holes therethrough. The dual compression driver further includes a second driver assembly that includes: a second motor assembly disposed about a central axis at a second end of the dual compression driver; a second annular diaphragm coaxially disposed below the second motor assembly and operatively connected to the second motor assembly; and a second phase plug coaxially mounted to the second motor assembly below the second annular diaphragm, the second phase plug including an input side oriented toward the second annular diaphragm and an output side oriented away from the second annular diaphragm, the second phase plug including a second plurality of holes therethrough. A hollow extension duct has a bottom end mounted to the first phase plug and a top end extending toward the second end of the dual compression driver, wherein an inner surface of the extension duct and an outer surface of the second driver assembly form an annular waveguide that terminates at an annular outlet at the second end of the dual compression driver. Acoustic signals from the first plurality of holes are combined with acoustic signals from the second plurality of holes between the output side of the first phase plug and the output side of the second phase plug and radiate radially outward into the annular waveguide and through the annular outlet. The waveguide is disposed on the top end of the extension duct and has an annular inlet adjacent the annular outlet of the dual compression driver.

[0016] In one or more embodiments, the extension duct includes an upper flange for mounting the waveguide. In one or more embodiments, the waveguide includes a rectangular outlet. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a cross-sectional view of a dual compression driver having an annular outlet according to one or more embodiments;

[0018] Figure 2 is a perspective view of a dual compression driver according to one or more embodiments;

[0019] Figure 3 is a top view of a dual compression driver according to one or more embodiments;

[0020] Figure 4 is a side view of a dual compression driver according to one or more embodiments;

[0021] Figure 5 is a perspective view of the input side of a rear phase plug according to one or more embodiments;

[0022] Figure 6 is a perspective view of the output side of a rear phase plug according to one or more embodiments;

[0023] Figure 7 is a perspective view of the output side of a front phase plug according to one or more embodiments;

[0024] Figure 8 is a perspective view of the input side of a front phase plug according to one or more embodiments;

[0025] Figure 9 is a perspective view of the hollow extension duct of a dual compression driver according to one or more embodiments;

[0026] Figure 10 is Figure 5 a top view of the extension duct;

[0027] Figure 11 is Figure 5 a bottom view of the extension duct mounted on the first phase plug;

[0028] Figure 12 is a schematic cross-sectional view of a dual compression driver showing the acoustic path through the driver to the annular outlet;

[0029] Figure 13 is a side view of the conical extension duct of a dual compression driver according to one or more embodiments;

[0030] Figure 14 is Figure 13 a top view of the conical extension duct;

[0031] Figure 15 is Figure 13 a bottom view of the conical extension duct;

[0032] Figure 16 is a schematic cross-sectional view of a dual compression driver with a conical extension duct according to one or more embodiments;

[0033] Figure 17 is a bottom perspective view of a corresponding waveguide with an annular inlet, the corresponding waveguide being used with a dual compression driver having an annular outlet; and

[0034] Figure 18 is Figure 17 A front perspective view of a waveguide according to one or more embodiments depicting a rectangular exit of the waveguide. DETAILED DESCRIPTION

[0035] As needed, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary embodiments of the invention, which can be embodied in various and alternative forms. The drawings are not necessarily to scale; some features may be enlarged or minimized to show details of particular components. Accordingly, the specific structural and functional details disclosed herein are not to be construed as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

[0036] It is to be understood that the directional identifiers (such as but not limited to top, bottom, above, below, upper, lower, upward, and downward) used herein for descriptive purposes are not intended to be limiting, but merely to provide an exemplary environment for the components of the dual compression driver disclosed herein. Any directional terms used herein are merely to indicate the relative positions of the various components of the dual compression driver and are not intended to limit the components to any particular orientation in space.

[0037] The configuration of existing dual compression drivers does not allow for an annular exit because the acoustic signal passes radially inward from an adjacent phase plug and then axially toward the circular exit of the dual driver. The disclosed embodiments enable an annular exit in a dual compression driver by radially guiding the output acoustic signal (outward instead of inward) in each phase plug. This configuration combines the acoustic signals from the two driver assemblies and radiates the combined acoustic signal outward and then upward toward the annular exit. The conduit for the signal to reach the annular exit is formed by the outer cylindrical surface of the dual driver and an extension conduit attached to the rear phase plug, as further described below. The disclosed embodiments are scalable and are advantageous for various applications, particularly line arrays.

[0038] First referring to Figures 1 to 4 , a dual compression driver 100 having an annular exit is disclosed herein, the dual compression driver including a first rear driver assembly 102 and a second front driver assembly 104, which can be used for a transducer or a speaker. The first driver assembly 102 and the second driver assembly 104 can be configured to operate in the same frequency range or in different frequency ranges. The various components of the dual compression driver 100 can be disposed generally about a central axis 106.

[0039] As Figure 1As shown in the cross-sectional view, the first driver assembly 102 includes a first motor assembly 108 that is disposed about a central axis 106 at the first end 110 of the dual compression driver 100, and the second driver assembly 104 includes a second motor assembly 112 that is disposed about the central axis 106 at the second end 114 of the dual compression driver 100. In one or more embodiments, the first motor assembly 108 may include a first annular permanent magnet 116 that is disposed between a first annular top plate 118 and a first back plate 120, the first back plate including a centrally disposed cylindrical or annular first pole shoe 122, and the second motor assembly 112 may include a second annular permanent magnet 124 that is disposed between a second annular top plate 126 and a second back plate 128, the second back plate including a centrally disposed cylindrical or annular second pole shoe 130. However, it should be understood that the first motor assembly 108 and the second motor assembly 112 are not limited to this configuration.

[0040] Continuing to refer Figure 1 , a first annular flexure diaphragm 132 is coaxially disposed above the first motor assembly 108 and is operatively connected to the first motor assembly, and a second annular flexure diaphragm 134 is coaxially disposed below the second motor assembly 112 and is operatively connected to the second motor assembly. In one or more embodiments, the first annular diaphragm 132 and the second annular diaphragm 134 may be formed of a polymer film. The first motor assembly 108 provides a permanent magnetic field for electro-dynamic coupling with a first voice coil 136, wherein the first voice coil 136 is mechanically coupled to the first annular diaphragm 132 and generates movement of a flexible portion of the first annular diaphragm 132 to convert a received electrical signal into an acoustic signal (sound wave). Similarly, the second motor assembly 112 provides a permanent magnetic field for electro-dynamic coupling with a second voice coil 138, wherein the second voice coil 138 is mechanically coupled to the second annular diaphragm 134 and generates movement of a flexible portion of the second annular diaphragm 134 to convert a received electrical signal into an acoustic signal. The first annular diaphragm 132 and the second annular diaphragm 134 may each include shaped sections, such as a first V-shaped section 140 and a second V-shaped section 142, respectively, having flat "wings" on either side, or the first annular diaphragm 132 and the second annular diaphragm 134 may have other suitable configurations.

[0041] Now turning to Figures 5 to 8, the first phase plug 144 is coaxially disposed above the first annular diaphragm 132 and includes a first input side 146 oriented toward the first annular diaphragm 132 and an output side 148 oriented away from the first annular diaphragm 132. The second phase plug 150 is coaxially disposed below the second annular diaphragm 134 and includes a second input side 152 oriented toward the second annular diaphragm 134 and a second output side 154 oriented away from the second annular diaphragm 134. The first phase plug 144 includes a first plurality of holes 156 extending from the first input side 146 to the first output side 148, and the second phase plug 150 includes a second plurality of holes 158 extending from the second input side 152 to the second output side 154.

[0042] In a compression driver, the diaphragm is loaded by a compression chamber, which is a thin layer of air separating the diaphragm from the phase plug. In the embodiments disclosed herein, as Figure 1 best shown in, a first compression chamber 160 is defined between the first input side 146 and the first annular diaphragm 132, wherein the first plurality of holes 156 form an outlet leading to the first compression chamber 160. A second compression chamber 162 is defined between the second input side 152 and the second annular diaphragm 134, wherein the second plurality of holes 158 form an outlet leading to the second compression chamber 162. The amount of air retained in the compression chamber is characterized by an acoustic compliance proportional to the volume of the compression chamber. In fact, the height of the compression chamber can be very small (e.g., about 0.5 mm or less), such that the volume of the compression chamber is also small. The small radial dimensions of the first annular diaphragm 132 and the second annular diaphragm 134 correspond to the small radial dimensions of the matching compression chambers 160, 162, which shifts the undesirable air resonances (cross modes) in the compression chambers 160, 162 to higher frequencies, sometimes above the audio range.

[0043] In one or more embodiments, the first phase plug 144 may include a first base 164 and a first mounting portion 166 extending downward from the first base 164 on the first input side 146 for mounting the first phase plug 144 to the first motor assembly 108 ( Figures 5 to 6 ). Correspondingly, the second phase plug 150 may include a second base 168 and a second mounting portion 170 extending axially downward from the second base 168 on the second input side 152 for mounting the second phase plug 150 to the second motor assembly 112( Figures 7 to 8)。In one or more embodiments, each of the first base 164 and the second base 168 can be generally disc-shaped and located in a plane orthogonal to the central axis 106. The first mounting portion 166 can be a hollow cylinder arranged to press-fit into a first groove 172 formed in the first pole shoe 122, and the second mounting portion 170 can be a hollow cylinder arranged to press-fit into a second groove 174 formed in the second pole shoe 130, as Figure 1 shown. However, it should be understood that the first mounting portion 166 and the second mounting portion 170 can have any configuration suitable for coupling the first phase plug 144 and the second phase plug 150 to the first motor assembly 108 and the second motor assembly 112, respectively.

[0044] A first central hole 176 coaxial with the central axis 106 is formed in the thickness (axial direction) of the first base 164, and a second central hole 178 coaxial with the central axis 106 is formed in the thickness of the second base 168. The fastener 180 can fix the first driver assembly 102 to the second driver assembly 104 through the second central hole (see Figure 1 ). Generally, the components of the first driver assembly 102 and the second driver assembly 104 can be connected together by fasteners or adhesives.

[0045] The acoustic signal generated by the first annular diaphragm 132 travels through a first plurality of holes 156 that serve as the inlet of the first phase plug 144, while the acoustic signal generated by the second annular diaphragm 134 travels through a second plurality of holes 158 that serve as the inlet of the second phase plug 150. Accordingly, the areas of the inlets of the first phase plug 144 and the second phase plug 150 are significantly smaller than the areas of the first annular diaphragm 132 and the second annular diaphragm 134, respectively. As Figures 5 to 8 shown, the first plurality of holes 156 and the second plurality of holes 158 can each be arranged circumferentially around the central axis 106, thus generally forming a circle. In one or more embodiments, the first plurality of holes 156 and the second plurality of holes 158 each have a "zigzag" or serrated configuration arranged circumferentially around the central axis 106, as shown. This serpentine configuration of the holes 156, 158 helps mitigate any adverse effects of diaphragm rupture on the frequency response and can have the effect of smearing the air resonance in the first compression chamber 160 and the second compression chamber 162 in order to shape and improve the wavefront leaving the dual compression driver 100. However, the first plurality of holes 156 and the second plurality of holes 158 are not limited to the embodiments depicted herein and can include other suitable shapes and configurations.

[0046] In one or more embodiments, the first output side 148 includes a first plurality of radial channels 182 extending outwardly from the first plurality of holes 156 ( Figure 6 ), and the second output side 154 includes a second plurality of radial channels 184 extending outwardly from the second plurality of holes 158 ( Figure 8 ). Accordingly, each hole 156, 158 is acoustically connected to a corresponding radial channel 182, 184. In one or more embodiments, the width of the first plurality of radial channels 182 expands from the first plurality of holes 156 toward the first outer edge 186 of the first phase plug 144, while the width of the second plurality of radial channels 184 expands from the second plurality of holes 158 toward the second outer edge 188 of the second phase plug 150, thereby providing a natural outward expansion of the wavefront. As Figure 12 best shown, in the embodiments disclosed herein, the first output side 148 faces the second output side 154 such that the first plurality of radial channels 182 and the second plurality of radial channels 184 form part of a shared acoustic path 190 for combining the acoustic signals from the first driver assembly 102 and the second driver assembly 104.

[0047] Now referring Figures 9 to 11 , the dual compression driver 100 further includes a hollow extension duct 192 having a bottom end 194 mounted to the first driver assembly 102 (such as to the first phase plug 144), and a top end 196 extending toward the second end 114 of the dual compression driver 100. To this end, the extension duct 192 can act as an extension of the first phase plug 144.

[0048] In one or more embodiments, the extension duct 192 can be generally cylindrical, wherein the inner surface 198 of the extension duct 192 includes a plurality of spaced-apart members 200 protruding from the inner surface 198 and defining an acoustic channel 202 therebetween. In one or more embodiments, each of the plurality of spaced-apart members 200 is wider at the bottom end 194 of the extension duct 192 than at its top end 196 such that the acoustic channel 202 expands from the bottom end 194 of the extension duct 192 to the top end 196. In one or more embodiments, the plurality of spaced-apart members 200 can have a generally triangular shape or a circular profile of a "bullet" shape (see Figure 14 ), but is not limited to these configurations. The size (such as width) of the plurality of spaced-apart members 200 can be uniform or non-uniform.

[0049] In one or more embodiments, the diameter of the first phase plug 144 is greater than the diameter of the second phase plug 150, as Figure 1 and Figure 12As shown, thereby providing an easily accessible installation area for the extension duct 192. Refer to Figure 6 , in the first phase plug 144, the first plurality of radial channels 182 may terminate inside the first outer edge 186, thereby providing an installation area 204 for positioning the extension duct 192 around the perimeter of the first phase plug 144. The installation area 204 may include spaced grooves 206 for receiving fasteners 208 to mount the extension duct 192 to the first phase plug 144. Correspondingly, the extension duct 192 may include spaced holes 210 therethrough at the bottom end 194 for receiving fasteners 208 to secure the extension duct 192 to the first phase plug 144.

[0050] Refer to Figures 1 to 3 and Figure 12 , in one or more embodiments, the second driver assembly 104 includes a housing 212 mounted at the second end 114 of the dual compression driver 100. The housing 212 has a bottom surface 214 disposed on or attached to the second driver assembly 104, and a top surface 216 that forms the outer surface of the second end 114 of the dual compression driver 100. As best shown in Figure 1 and Figure 12 , the inner surface 198 of the extension duct 192 and the outer surface 218 of the second driver assembly 104 together form an annular passage 220 that terminates at an annular outlet 222 at the second end 114 of the dual compression driver 100. The outer side surface 224 of the housing 212 may form at least a portion of the annular passage 220. In operation, the acoustic signals from the first plurality of holes 156 are combined with the acoustic signals from the second plurality of holes 158 between the first output side 148 and the second output side 154, and radiate radially outward into the annular passage 220, where the acoustic channel 202 provides a natural upward expansion of the wavefront through the annular outlet 222 of the dual compression driver 100. The total acoustic cross-sectional area of the air path (including the first plurality of holes 156 and the second plurality of holes 158, the first plurality of radial channels 182 and the second plurality of radial channels 184, and the acoustic channel 202) gradually increases to provide a smooth transition of the acoustic signal through the dual compression driver 100.

[0051] As shown in Figures 13 to 16 , in one or more embodiments, the extension duct 192 may alternatively have a generally frustoconical shape, with its width expanding from the bottom end 194 to the top end 196. Unlike the embodiment in Figures 9 to 11 where the transition angle of the shared acoustic path 190 to the annular passage 220 is approximately 90 degrees, in this embodiment, the transition angle may be approximately 120 degrees. As shown in Figure 16As best shown, the outer housing 212 can substantially surround the second driver assembly 104, where the top end 226 of the outer housing is wider than the bottom end 228, and the side surface 224 has a generally straight and smooth profile from the bottom end 194 to the top end 196. Accordingly, the annular passage 220 can be formed by the inner surface 198 of the extension duct 192 and the outer surface 224 of the outer housing 212.

[0052] Figures 17 to 18 An exemplary waveguide 230 of the dual compression driver 100 is shown. In one or more embodiments, the waveguide 230 can have an annular inlet 232 and a rectangular outlet 234. The waveguide 230 can be used to control the directivity (i.e., the sound pressure coverage over a specific listening area) of sound waves propagating from the dual compression driver 100 into the surrounding environment and to increase the reproduced SPL within a specific frequency range. The rectangular outlet 234 has a smaller dimension in the horizontal plane and a larger dimension in the vertical plane, thus providing a wide directivity response (wider dispersion) in the horizontal plane and a narrower dispersion in the vertical plane. Such a configuration is optimal for forming the cylindrical wavefront required in a line array cluster, although the waveguide 230 is not limited to this configuration. The waveguide 230 can be received and mounted on the top end 196 of the extension duct 192, where the annular inlet 232 is adjacent to and aligned with the annular outlet 222 of the dual compression driver 100. In one or more embodiments, the extension duct 192 can include an upper flange 236 for receiving and mounting the waveguide 230. Sound waves enter through the annular outlet 222 of the dual compression driver 100, radiate through the rectangular outlet 234 via the waveguide 230, and propagate into the surrounding environment.

[0053] Although the exemplary embodiments are described above, it does not mean that these embodiments describe all possible forms of the invention. On the contrary, the words used in this specification are descriptive words rather than limiting words, and it should be understood that various changes can be made without departing from the spirit and scope of the invention. Additionally, the features of the various implementation embodiments can be combined to form additional embodiments of the invention.

Claims

1. A dual compression driver comprising: a first driver assembly comprising: a first motor assembly disposed about a central axis at a first end of the dual compression driver; a first annular diaphragm coaxially disposed above the first motor assembly and operably connected to the first motor assembly; and a first phase plug coaxially disposed above the first annular diaphragm, the first phase plug comprising an input side oriented toward the first annular diaphragm and an output side oriented away from the first annular diaphragm, the first phase plug comprising a first plurality of holes therethrough; a second driver assembly, the second driver assembly comprising: a second motor assembly disposed about the central axis at a second end of the dual compression driver; a second annular diaphragm coaxially disposed below the second motor assembly and operably connected to the second motor assembly; and a second phase plug coaxially disposed below the second annular diaphragm, the second phase plug comprising an input side oriented toward the second annular diaphragm and an output side oriented away from the second annular diaphragm, the second phase plug comprising a second plurality of holes therethrough; and a hollow extension conduit having a bottom end mounted to the first phase plug and a top end extending toward the second end of the dual compression driver, wherein an inner surface of the extension conduit and an outer surface of the second driver assembly form an annular passage terminating in an annular outlet at the second end of the dual compression driver, wherein acoustic signals from the first plurality of holes combine with acoustic signals from the second plurality of holes between the output side of the first phase plug and the output side of the second phase plug and radiate radially outward to the annular passage and through the annular outlet.

2. A dual compression driver as described in claim 1, wherein the second driver assembly includes a housing mounted at the second end of the dual compression driver, and a side surface of the housing forms at least a portion of the annular passage.

3. The dual compression driver of claim 1, wherein a diameter of the first phase plug is greater than a diameter of the second phase plug.

4. The dual compression driver of claim 1, wherein the extension conduit is generally cylindrical.

5. The dual compression driver of claim 1, wherein the inner surface of the extension duct comprises a plurality of spaced apart members defining acoustic passages therebetween.

6. A dual compression driver as described in claim 5, wherein each of the plurality of spaced-apart members is wider at the bottom end of the extension duct than at the top end, so that the acoustic path expands from the bottom end of the extension duct to the top end of the extension duct.

7. The dual compression driver of claim 1, wherein the first motor assembly includes a first annular magnet and the second motor assembly includes a second annular magnet.

8. The dual compression driver of claim 1, wherein the first plurality of holes and the second plurality of holes are each generally circumferentially arranged about the central axis.

9. The dual compression driver of claim 8, wherein the first plurality of holes and the second plurality of holes each have a zigzag configuration about the central axis.

10. A dual compression driver as described in claim 1, wherein the output side of the first phase plug includes a first plurality of radial channels extending outward from the first plurality of holes, and the output side of the second phase plug includes a second plurality of radial channels extending outward from the second plurality of holes, the first plurality of radial channels and the second plurality of radial channels forming a portion of a shared acoustic path for directing the combined acoustic signal to the annular passage.

11. The dual compression driver of claim 10, wherein the width of the first plurality of radial channels expands from the first plurality of holes toward an outer edge of the first phase plug, and the width of the second plurality of radial channels expands from the second plurality of holes toward an outer edge of the second phase plug.

12. The dual compression driver of claim 1 , wherein the first phase plug comprises: a first base and a first mounting portion, wherein the first mounting portion extends downward from the first base on the input side of the first phase plug for mounting to the first motor assembly; and the second phase plug includes a second base and a second mounting portion, wherein the second mounting portion extends upward from the second base on the input side of the second phase plug for mounting to the second motor assembly.

13. A dual compression driver as described in claim 1, wherein a first compression chamber is defined between the input side of the first phase plug and the first annular diaphragm, and a second compression chamber is defined between the input side of the second phase plug and the second annular diaphragm, the first plurality of holes form an outlet to the first compression chamber, and the second plurality of holes form an outlet to the second compression chamber.

14. A dual compression driver comprising: a first driver assembly comprising: a first motor assembly disposed about a central axis at a first end of the dual compression driver; a first annular diaphragm coaxially disposed above the first motor assembly and operably connected to the first motor assembly; and a first phase plug coaxially disposed above the first annular diaphragm, the first phase plug comprising an input side oriented toward the first annular diaphragm and an output side oriented away from the first annular diaphragm, the first phase plug comprising a first plurality of holes therethrough; a second driver assembly, the second driver assembly comprising: a second motor assembly disposed about the central axis at a second end of the dual compression driver; a second annular diaphragm coaxially disposed below the second motor assembly and operably connected to the second motor assembly; and a second phase plug coaxially disposed below the second annular diaphragm, the second phase plug comprising an input side oriented toward the second annular diaphragm and an output side oriented away from the second annular diaphragm, the second phase plug comprising a second plurality of holes therethrough; a hollow extension tube having a bottom end mounted to the first phase plug and a top end extending toward the second end of the dual compression driver; and a housing mounted to the second driver assembly at the second end of the dual compression driver, wherein the inner surface of the extension conduit and the outer surface of the housing form an annular passage terminating in an annular outlet at the second end of the dual compression driver, wherein acoustic signals from the first plurality of holes combine with acoustic signals from the second plurality of holes between the output side of the first phase plug and the output side of the second phase plug and radiate radially outward to the annular passage and through the annular outlet.

15. A dual compression driver as described in claim 14, wherein the extension tube has a generally frustoconical shape, which gradually increases in width from the bottom end of the extension tube to the top end of the extension tube, and wherein the housing substantially surrounds the second driver assembly, wherein the top end of the housing is wider than the bottom end of the housing.

16. The dual compression driver of claim 14, wherein a diameter of the first phase plug is greater than a diameter of the second phase plug.

17. A dual compression driver as described in claim 14, wherein the inner surface of the extension duct includes a plurality of spaced-apart members, and an acoustic channel is defined between the plurality of spaced-apart members, wherein each of the plurality of spaced-apart members is wider at the bottom end of the extension duct than at the top end, so that the acoustic channel expands from the bottom end of the extension duct to the top end of the extension duct.

18. A transducer comprising: Dual compression drivers include a first driver assembly, the first driver assembly comprising: a first motor assembly, the first motor assembly disposed about a central axis at a first end of the dual compression driver; a first annular diaphragm, the first annular diaphragm coaxially disposed above the first motor assembly and operably connected to the first motor assembly; and a first phase plug, the first phase plug coaxially mounted to the first motor assembly above the first annular diaphragm, the first phase plug including an input side oriented toward the first annular diaphragm and an output side oriented away from the first annular diaphragm, the first phase plug including a first plurality of holes therethrough; a second driver assembly, the second driver assembly comprising: a second motor assembly disposed about a central axis at a second end of the dual compression driver; a second annular diaphragm coaxially disposed below the second motor assembly and operably connected to the second motor assembly; and a second phase plug coaxially mounted to the second motor assembly below the second annular diaphragm, the second phase plug comprising an input side oriented toward the second annular diaphragm and an output side oriented away from the second annular diaphragm, the second phase plug comprising a second plurality of holes therethrough; and a hollow extension tube having a bottom end mounted to the first phase plug and a top end extending toward the second end of the dual compression driver, wherein an inner surface of the extension tube and an outer surface of the second driver assembly form an annular waveguide terminating in an annular outlet at the second end of the dual compression driver, wherein acoustic signals from the first plurality of holes combine with acoustic signals from the second plurality of holes between the output side of the first phase plug and the output side of the second phase plug and radiate radially outward to the annular waveguide and through the annular outlet; and A waveguide is disposed on the top end of the extension conduit, the waveguide having an annular inlet adjacent the annular outlet of the dual compression driver.

19. The transducer of claim 18, wherein the extension conduit includes an upper flange for mounting the waveguide.

20. The transducer of claim 18, wherein the waveguide comprises a rectangular outlet.

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