A small speaker with multiple sound cones

Abstract

The present invention discloses a small speaker with multiple sound cones and no positioning support, which improves the clarity of the speaker's original sound reproduction, has better bass and directivity width, and has higher sensitivity and less distortion. A small speaker with multiple sound cones, including a basin frame and a sound cone assembly arranged on the basin frame, the sound cone assembly includes a central sound cone and an outer sound cone, the small speaker also includes a central driving mechanism for driving the central sound cone to vibrate and a plurality of outer driving mechanisms for driving the outer sound cones to vibrate, the outer driving mechanisms are arranged on the periphery of the central driving mechanism, the central driving mechanism includes a central voice coil connected to the central sound cone and a central magnetic circuit system for driving the central voice coil, and each of the outer driving mechanisms includes an outer voice coil connected to the corresponding outer sound cone and an outer magnetic circuit system for driving the outer voice coil.

Description

Technical Field

[0001] The invention belongs to the field of loudspeakers, and relates to a small loudspeaker with multiple sound cones, in particular to a small loudspeaker with multiple sound cones without positioning supports and capable of inputting multiple-channel audio input signals. Background Art

[0002] The existing traditional small speakers without fixed support plates generally use a disc-shaped cone, which is connected to a voice coil to form a speaker vibration system without fixed support plates. This speaker without fixed support plates can only be used for single-channel signal input. Single-channel audio signal input has limitations on original sound playback, and the combination of a single voice coil and a cone has high requirements for the rigidity of the cone material. Although the voice coil of this speaker can also use a voice coil that can input multiple signals. This voice coil is formed by stacking multiple groups of coils from the inside to the outside, and the disc-shaped cone and the fixed support plates are glued to the outer wall of the voice coil to form a speaker vibration system. This speaker can be used for multiple signal inputs. However, since this speaker has multiple groups of coils wound on one voice coil, the weight of the voice coil is increased when the voice coil drives the cone. When this voice coil drives the cone, the sensitivity of the speaker is affected and may be reduced. Summary of the invention

[0003] In view of the above problems, the present invention provides a small loudspeaker with multiple cones and no positioning supports, which improves the clarity of the original sound reproduction of the loudspeaker and has higher sensitivity.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A small speaker with multiple cones, comprising a cone frame and a cone assembly arranged on the cone frame, the cone assembly comprising a central cone and multiple outer cones, the multiple outer cones being arranged in sequence along the circumference of the central cone, the small speaker also comprising a central driving mechanism and multiple outer driving mechanisms arranged around the periphery of the central driving mechanism, the central cone is driven by the central driving mechanism to vibrate and produce sound, and each of the outer cones is driven by one of the outer driving mechanisms to vibrate and produce sound, the central driving mechanism comprises a central voice coil connected to the central cone and a central magnetic circuit system for driving the central voice coil, and each of the outer driving mechanisms comprises an outer voice coil connected to the corresponding outer cone and an outer magnetic circuit system for driving the outer voice coil.

[0006] Preferably, the plurality of outer sound basins are spliced ​​together to form a ring surrounding the central sound basin, and the central sound basin and the plurality of outer sound basins are independently arranged on the basin frame. More preferably, the shape of each outer sound basin is generally a fan ring. Furthermore, the area of ​​each outer sound basin is generally equal.

[0007] Preferably, the basin frame includes a basin frame bottom and an inner flange extending upward from the basin frame bottom, a basin frame side and a radial flange, the basin frame side surrounds the periphery of the inner flange, the radial flange extends radially along the bottom of the basin frame and is located between the inner flange and the basin frame side, the outer peripheral edge of the central sound basin is fixedly connected to the inner flange, each of the outer sound basins is roughly fan-shaped, the outer edge of each outer sound basin is fixedly connected to the basin frame side, the inner edge of each outer sound basin is fixedly connected to the inner flange, and the two side edges of each outer sound basin are fixedly connected to two adjacent radial flanges.

[0008] More preferably, the central magnetic circuit system and the outer magnetic circuit system are fixedly arranged on the bottom of the basin frame, and the central voice coil and the outer voice coil are located between the sound basin assembly and the bottom of the basin frame.

[0009] More preferably, the central magnetic circuit system and the external magnetic circuit system are fixedly arranged below the bottom of the basin frame, and a central through hole and a plurality of peripheral through holes are opened on the bottom of the basin frame. The lower end of the central voice coil passes through the central through hole and is inserted into the magnetic gap of the central magnetic circuit system, and the lower end of each of the outer voice coils passes through the corresponding peripheral through holes and is inserted into the magnetic gap of the outer magnetic circuit system.

[0010] Furthermore, the bottom of the basin frame is roughly in the shape of a flat plate.

[0011] Furthermore, the central magnetic circuit system and each of the outer magnetic circuit systems respectively include a U-iron with an inner cavity, a magnetic steel and a magnetic pole core arranged in the U-iron, the upper end of the U-iron is fixedly connected to the bottom of the basin frame, and a magnetic gap is formed between the magnetic steel and the magnetic pole core and the inner wall of the U-iron for the central voice coil or the outer voice coil to be inserted.

[0012] More preferably, the central voice coil and each of the outer voice coils have a pair of leads, and the end of each of the leads is connected to an input terminal that can be electrically connected to an amplifier, and the input terminal is embedded on the lower surface of the bottom of the basin frame. Further, the outer surface of the side plate of the basin frame is provided with a plurality of outlet grooves corresponding to each of the input terminals.

[0013] Preferably, the central portion of the central sound basin has an upwardly arched dome or a flat plate-shaped main body, and the outer sound basin has a flat plate-shaped main body. When the central sound basin and the outer sound basin respectively adopt a flat plate-shaped main body, the height of the central sound basin and the outer sound basin can be lower than the height of the traditional disc-shaped sound basin, and the directivity width of the product is better than that of the traditional disc-shaped sound basin speaker.

[0014] Preferably, a fixing step for connecting to the central voice coil is formed on the lower surface of the central sound cone; and / or a plurality of fixing steps for connecting to the outer voice coil are formed on the lower surface of the outer sound cone.

[0015] Preferably, a plurality of the outer driving mechanisms are arranged at equal intervals around the periphery of the central driving mechanism.

[0016] Preferably, the small speaker does not include a positioning support.

[0017] Herein, "multi-cone" means that the total number of cones is equal to or greater than three, preferably at least four.

[0018] The present invention adopts the above solution, which has the following advantages compared with the prior art:

[0019] The small speaker of the present invention has an ingenious and reasonable product structure. The central voice coil is vibrated up and down in the central magnetic circuit system by inputting audio signals, and the central sound basin is driven to sound by inputting multiple groups of outer voice coils by multi-channel audio signals. The outer voice coils vibrate up and down in the external magnetic circuit system to drive the outer sound basin to sound. The central sound basin emits medium and high pitches. The bass performance of the speaker is increased and expanded by the outer sound basin, the bandwidth and directivity of the speaker are widened, and the distortion of the speaker is reduced. The sensitivity of the speaker is increased by combining the central voice coil with multi-stage outer voice coils, and each sound basin is driven by the central magnetic circuit system and the external magnetic circuit system respectively. The original sound reproduction effect of the speaker can be improved by inputting multiple audio signals to the central voice coil and the outer ring voice coil respectively, and the central sound basin and the outer ring sound basin are driven. In addition, each outer voice coil is independent of each other and does not interfere with each other. The audio signals input to each outer voice coil can be different, so that the small speaker is suitable for use as a digital speaker and can be used to build a digital speaker system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solution of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0021] Figure 1 is an exploded schematic diagram of a small speaker according to an embodiment of the present invention;

[0022] Figure 2 for Figure 1 Schematic diagram of the basin frame and voice coil in;

[0023] Figure 3 for Figure 1 A front view of a basin frame with a voice coil installed in FIG.

[0024] Figure 4 for Figure 1 Schematic diagram of the back of the basin frame with the voice coil installed.

[0025] in:

[0026] 1. basin frame; 11. basin frame bottom; 111. center through hole; 112. peripheral through hole; 12. inner flange; 13. basin frame side; 131. outlet groove; 14. radial flange;

[0027] 2. Sound cone assembly; 21. Center sound cone; 211. Dome; 22. External sound cone; 221. Folding ring;

[0028] 31. Center voice coil; 32. Outer voice coil; 33. Lead wire; 34. Input terminal;

[0029] 4a, central magnetic circuit system; 4b, external magnetic circuit system; 41, U iron; 42, magnetic steel; 43, magnetic pole core. DETAILED DESCRIPTION

[0030] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0031] In the description of the present application, it should be understood that the terms "center", "up", "down", "bottom", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0032] This embodiment provides a small speaker with multiple sound cones, specifically a small speaker without positioning support. In this article, "multiple sound cones" means that the total number of sound cones is equal to or greater than three, preferably at least four. Figures 1 to 4As shown, the multi-cone small speaker includes a basin frame 1 and a basin assembly 2 arranged on the basin frame 1. The basin assembly 2 includes a central basin 21 and multiple outer basins 22, and the multiple outer basins 22 are arranged in sequence along the axial direction of the central basin 21. The mid-range basin 21 and the multiple outer basins 22 are independently arranged on the basin frame 1 without interfering with each other. The small speaker also includes a central driving mechanism for driving the central basin 21 to vibrate and produce sound, and multiple outer driving mechanisms for driving the outer basins 22 to vibrate. The outer driving mechanisms are arranged on the periphery of the central driving mechanism, and each outer driving mechanism corresponds to an outer basin 22, and each outer basin 22 is driven to vibrate and produce sound by the corresponding outer driving mechanism. Further, multiple outer driving mechanisms are arranged around the periphery of the central driving mechanism at equal intervals. The central driving mechanism includes a central voice coil 31 connected to the central basin 21 and a central magnetic circuit system 4a for driving the central voice coil 31, and each outer driving mechanism includes an outer voice coil 32 connected to the corresponding outer basin 22 and an outer magnetic circuit system 4b for driving the outer voice coil 32. Preferably, the number of the outer voice coils 32 is three or more, which are arranged at equal intervals along a circle, and the center of the circle falls on the midpoint of the central voice coil 31. The central voice coil 31 drives the central cone 21 to vibrate and produce sound, and the central cone 21 is responsible for producing sound at medium and high frequencies. Each outer voice coil 32 drives the corresponding outer cone 22 to vibrate and produce sound, and the outer cone 22 is responsible for producing sound at medium and low frequencies. Multiple outer voice coils 32 can input multiple different analog or digital audio signals, thereby improving the original sound reproduction performance of the speaker.

[0033] When viewed from above, the central sound cone 21 has a substantially circular outer contour. The plurality of outer sound cones 22 are spliced ​​together to form a ring surrounding the central sound cone 21. Preferably, the overall shape of each outer sound cone 22 is substantially a fan ring, and the areas of each outer sound cone 22 are substantially equal. Figure 1 In the embodiment shown, three outer sound cones 22 are arranged in sequence and spaced apart on the periphery of the central sound cone 21. The central sound cone 21 is arranged in the middle of the basin frame 1, and the plurality of outer sound cones 22 are independently arranged on the basin frame 1. In one embodiment, the central sound cone 21 and the outer sound cones 22 respectively have a flat plate-shaped main body, and reinforcing ribs are provided on the back of the main bodies of the two to improve the working strength and rigidity, which is used to enhance the strength of the voice coil when pushing the sound cone. The height of the central sound cone 21 and the outer sound cone 22 is lower than that of the traditional disc-shaped sound cone. At the same time, when the central sound cone 21 and the outer sound cone 22 are in the shape of a flat plate, the directivity width of the product is better than that of the traditional disc-shaped sound cone speaker. In another embodiment, the middle part of the central sound cone 21 has an upwardly arched dome 211 to increase the extension of the treble frequency.

[0034] The basin frame 1 includes a basin frame bottom 11, an inner flange 12 extending upward from the basin frame bottom 11, a basin frame side 13 and a radial flange 14. The inner flange 12 as a whole is roughly annular and matches the outer contour of the central sound basin 21. The basin frame side 13 surrounds the periphery of the inner flange 12 and is also roughly annular, and the two are roughly concentric rings. The radial flange 14 extends radially along the basin frame bottom 11 and is located between the inner flange 12 and the basin frame side 13. The outer periphery of the central sound basin 21 is fixedly connected to the inner flange 12. The inner periphery of each outer sound basin 22 is fixedly connected to the inner flange 12 by a folding ring 221, and the inner periphery of the outer sound basin 22 and the outer periphery of the central sound basin 21 do not intersect, and the two do not connect to each other. The outer periphery of each outer sound basin 22 is connected to the basin frame side 13 by a folding ring 221. The two sides of each outer sound basin 22 are fixedly connected by the folding ring 221 and the two adjacent radial flanges 14, and the sides of the two adjacent outer sound basins 22 are not connected to each other, and the two are separated by the ridges on the radial flanges 14. The central magnetic circuit system 4a and the outer magnetic circuit system 4b are fixedly arranged on the bottom 11 of the basin frame, and the central voice coil 31 and the outer voice coil 32 are located between the sound basin assembly 2 and the bottom 11 of the basin frame. Preferably, the central magnetic circuit system 4a and the outer magnetic circuit system 4b are fixedly arranged below the bottom 11 of the basin frame, and the bottom 11 of the basin frame is provided with a central through hole 111 and a plurality of peripheral through holes 112, the central through hole 111 is provided between the inner flanges 12, and the peripheral through holes are provided between the two adjacent radial flanges 14. The lower end of the central voice coil 31 passes through the central through hole 111 and is inserted into the magnetic gap of the central magnetic circuit system 4a, and the lower end of each outer voice coil 32 passes through the corresponding peripheral through hole 112 and is inserted into the magnetic gap of the outer magnetic circuit system 4b.

[0035] The central magnetic circuit system 4a and each outer magnetic circuit system 4b respectively include a U-iron 41 with an inner cavity, a magnet 42 and a pole core 43 arranged in the U-iron 41. The upper end of the U-iron 41 is fixedly connected to the bottom 11 of the basin frame, and a magnetic gap is formed between the magnet 42 and the pole core 43 and the inner wall of the U-iron 41 for the central voice coil 31 or the outer voice coil 32 to be inserted. The above-mentioned center through hole 111 is opened at the center of the bottom 11 of the basin frame, and the upper end of the U iron 41 of the center magnetic circuit system 4a is fixedly arranged in the center through hole 111. The pole core 43 and the neodymium magnet 42 are installed in the U iron 41. The lower surface of the pole core 43 and the upper surface of the neodymium magnet 42 are tightly fitted, and the lower surface of the neodymium magnet 42 and the upper surface of the bottom of the U iron 41 are tightly fitted. There is a gap between the outer surface of the pole core 43 and the neodymium magnet 42 and the inner surface of the U iron 41, thereby forming a magnetic gap for the center voice coil 31 to be inserted. The above-mentioned multiple peripheral through holes 112 are evenly distributed around the central through hole 111, and the upper ends of the U irons 41 of the external magnetic circuit systems 4b are respectively fixedly arranged in the corresponding peripheral through holes 112. The pole core 43 and the neodymium magnet 42 are installed in the U iron 41. The lower surface of the pole core 43 and the upper surface of the neodymium magnet 42 are closely fitted, and the lower surface of the neodymium magnet 42 and the upper surface of the bottom of the U iron 41 are closely fitted. There is a gap between the outer surface of the pole core 43 and the neodymium magnet 42 and the inner surface of the U iron 41, thereby forming a magnetic gap for the outer voice coil 32 to be inserted. Preferably, the basin frame 1 is formed by plastic injection molding, and the U iron 41 is embedded in the basin frame 1 during the injection molding process, thereby improving the assembly accuracy.

[0036] The central voice coil 31 and each outer voice coil 32 each have a pair of leads 33. The end of each lead 33 is connected to an input terminal 34, which is embedded in the side 13 of the frame. Specifically, each voice coil is provided with a group of positive and negative leads 33, and each group of leads 33 is connected to two input terminals 34 provided on the side 13 of the frame. When the speaker needs to be connected to the power amplifier, the male connector connected to the power amplifier can be inserted into the female connector, and the input terminal 34 therein is connected to realize the transmission of the audio signal. A plurality of outlet grooves 131 are provided on the outer surface of the side 13 of the frame, and each input terminal 34 corresponds to an outlet groove 121, which is used to accommodate the wires that connect the input terminal 34 to the outside world. Multiple analog audio signals or digital audio signals can be input to the central voice coil 31 and each outer voice coil 32 through multiple input terminals 34, thereby improving the original sound reproduction performance of the speaker.

[0037] A fixed step for connecting the central voice coil 31 is formed on the lower surface of the central sound cone 21, and the upper end of the central voice coil 31 is tightly fitted with the fixed step. A fixed step for connecting the outer voice coil 32 is formed on the lower surface of each outer sound cone 22, and the upper end of the outer voice coil 32 is tightly fitted with the corresponding fixed step.

[0038] The material of the basin frame 1 is plastic or metal. The central sound basin 21 and the outer sound basin 22 are made of different materials, such as plastic (PP), paper, cloth (silk), metal or alloy (aluminum alloy), and can be a film material. The folding ring 221 is made of the same material as the outer sound basin 22, or a combination of one or more of sponge, rubber, and cloth. It has the advantages of light weight, good damping elasticity and rigidity, high temperature and low temperature resistance, waterproof and mildew resistance.

[0039] The small loudspeaker of this embodiment has the following characteristics: a central sound cone 21 with a spherical top 211 is provided at the center of the basin frame 1, a fixed voice coil step is provided at the lower end of the central sound cone 21, and a central voice coil 31 is fixed on the fixed step of the central sound cone 21 to form a vibration system for mid-high frequency sound production; three outer sound cones 22 with a planar main body are evenly arranged on the periphery of the central sound cone 21, and the inner edge and the outer end of the outer sound cone 22 are respectively provided with folding rings, and the bottom of the outer sound cone 22 is provided with a step for fixing the voice coil, and the three outer voice coils 32 are fixed on the steps of the corresponding outer sound cone 22 to form a vibration system for mid-low frequency sound production, thereby forming a multi-sound cone, multi-magnetic circuit, and non-positioning support loudspeaker. This type of speaker adopts a multi-cone, multi-magnetic circuit and multi-voice coil driving structure. Compared with the traditional speaker without positioning support, it adopts multiple cones, that is, the central cone 21 is responsible for the mid-high sound, and the multiple outer cones 22 are responsible for the mid-bass sound. The combination of multiple cones is beneficial to improving the clarity of the speaker's original sound reproduction, and the speaker's bass and directivity width are also better than traditional cone speakers; by adopting a single-channel signal input to drive the central voice coil 31 to move up and down in the U-iron 41 magnetic circuit, and by using multiple audio signal inputs to drive the multiple voice coils in the outer circle to move up and down in the multiple U-iron 41 magnetic circuits, the structure promotes the central cone 21 and the flat outer cone 22 to sound, and can also increase the speaker sensitivity and reduce the speaker distortion.

[0040] The product structure of this small speaker is ingenious and reasonable. The audio signal is input to the central voice coil 31 to vibrate up and down in the central magnetic circuit to drive the central sound cone 21 (flat or spherical) to make sound; multi-channel audio signals are input to multiple groups of outer voice coils 32 respectively, and the outer voice coils 32 vibrate up and down in the magnetic circuit to drive multiple outer sound cones 22 to make sound. The center cone 21 is flat or has a dome in the middle to produce medium and high-frequency sounds. The flat outer cone 22 increases and expands the bass performance of the speaker, widens the bandwidth and directivity of the speaker, and reduces the distortion of the speaker. The center voice coil 31 and the multi-stage outer voice coil 32 are combined, and the multiple cones are driven respectively by the center magnetic circuit system 4a and the outer magnetic circuit system 4b, so that the sensitivity of the speaker is increased. The center cone 21 in the multiple cones adopts a flat or spherical structure, and the outer cone adopts a flat plate shape and an inner and outer circle folded ring structure, which reduces the height of the cone and thus reduces the height of the product. Multi-channel audio signals are respectively input into the center voice coil 31 and the outer coil to drive the center cone 21 and the outer cone, so as to improve the original sound reproduction effect of the speaker.

[0041] The above embodiment is only for illustrating the technical concept and features of the present invention, and is a preferred embodiment. Its purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and it cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A small speaker with multiple sound cones, comprising a basin frame and a sound cone assembly arranged on the basin frame, characterized in that: The sound cone assembly includes a central sound cone and multiple outer sound cones, and the multiple outer sound cones are arranged along the circumference of the central sound cone. The small speaker also includes a central driving mechanism and multiple outer driving mechanisms arranged around the periphery of the central driving mechanism. The central sound cone is driven by the central driving mechanism to vibrate and produce sound, and each of the outer sound cones is driven by one of the outer driving mechanisms to vibrate and produce sound. The central driving mechanism includes a central voice coil connected to the central sound cone and a central magnetic circuit system for driving the central voice coil, and each of the outer driving mechanisms includes an outer voice coil connected to the corresponding outer sound cone and an outer magnetic circuit system for driving the outer voice coil.

2. The small speaker according to claim 1, characterized in that: The multiple outer sound basins are spliced ​​together to form a ring surrounding the central sound basin, and the central sound basin and the multiple outer sound basins are independently arranged on the basin frame.

3. The small speaker according to claim 2, characterized in that: The basin frame includes a basin frame bottom and an inner flange extending upward from the basin frame bottom, a basin frame side and a radial flange, the basin frame side surrounds the outer periphery of the inner flange, the radial flange extends radially along the bottom of the basin frame and is located between the inner flange and the basin frame side, the outer peripheral edge of the central sound basin is fixedly connected to the inner flange, each of the outer sound basins is fan-shaped, the outer edge of each outer sound basin is fixedly connected to the basin frame side, the inner edge of each outer sound basin is fixedly connected to the inner flange, and the two side edges of each outer sound basin are fixedly connected to two adjacent radial flanges.

4. The small speaker according to claim 3, characterized in that: The central magnetic circuit system and the outer magnetic circuit system are fixedly arranged on the bottom of the basin frame, and the central voice coil and the outer voice coil are located between the sound basin assembly and the bottom of the basin frame.

5. The small speaker according to claim 4, characterized in that: The central magnetic circuit system and the outer magnetic circuit system are fixedly arranged below the bottom of the basin frame. A central through hole and multiple peripheral through holes are opened on the bottom of the basin frame. The lower end of the central voice coil passes through the central through hole and is inserted into the magnetic gap of the central magnetic circuit system. The lower ends of each outer voice coil pass through the corresponding peripheral through hole and are inserted into the magnetic gap of the outer magnetic circuit system.

6. The small speaker according to claim 5, characterized in that: The bottom of the basin frame is in a flat plate shape.

7. The small speaker according to claim 5, characterized in that: The central magnetic circuit system and each of the outer magnetic circuit systems respectively include a U-iron with an inner cavity, a magnetic steel and a magnetic pole core arranged in the U-iron, the upper end of the U-iron is fixedly connected to the bottom of the basin frame, and a magnetic gap is formed between the magnetic steel and the magnetic pole core and the inner wall of the U-iron for the central voice coil or the outer voice coil to be inserted.

8. The small speaker according to claim 5, characterized in that: The central voice coil and each of the outer voice coils have a pair of leads respectively, and the end of each of the leads is respectively connected to an input terminal that can be electrically connected to a power amplifier, and the input terminal is embedded on the lower surface of the bottom of the basin frame.

9. The small speaker according to claim 1, characterized in that: The central sound cone has a dome that arches upward or a flat plate-shaped main body in the middle, and the outer sound cone has a flat plate-shaped main body.

10. The small speaker according to claim 1, characterized in that: A fixing step for connecting the central voice coil is formed on the lower surface of the central sound cone; and / or a plurality of fixing steps for connecting the outer voice coil are formed on the lower surface of the outer sound cone.

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