An active ultra-low frequency sound system

Abstract

The present invention discloses an active ultra-low frequency sound speaker, which comprises a box body and a base. A loudspeaker unit is connected inside the inner cavity of the box body, and the outer end of the chassis of the loudspeaker unit is connected in the mounting hole at the bottom of the box body. The opening of the conical paper cone inside the chassis is arranged downward; there is a radiation space between the base and the bottom of the box body; a protruding part protruding upward is arranged at the top of the base, and the top of the protruding part extends upward through the opening of the conical paper cone and is arranged inside the conical paper cone; an annular compression cavity is formed between the outer side wall of the protruding part and the inner wall of the conical paper cone, and the periphery of the compression cavity is communicated with the radiation space; this active ultra-low frequency sound speaker can effectively reduce standing wave distortion, does not affect the smoothness of sound wave radiation, improves the compliance of the loudspeaker unit, and has strong and powerful bass and high sound reproduction quality.

Description

Technical Field

[0001] The present invention relates to the technical field of audio equipment, and specifically relates to an active subwoofer audio. Background Art

[0002] An audio generally refers to a set of audio systems that combine electrical equipment to emit sound; with the progress of society and the development of technology, people's pursuit of the quality of life is getting higher and higher. After work, people need wonderful music and various forms of singing and dancing to relieve work fatigue and make people's spirits relaxed and physically and mentally happy; the audio system is continuously improved and perfected according to people's needs, which can meet the needs of live sound amplification for tens of thousands of people at large, and can meet the needs of individuals for playing musical instruments and singing at home at small. In audio technology, the pitch of sound, that is, the intensity and amplitude of the audio, is one of the important indicators for evaluating the quality of audio sound quality, that is, whether the pitch relative to a certain frequency or frequency band has a certain intensity, and within the required frequency range and at the same volume, whether the amplitudes of each frequency point are uniform, balanced, and full, whether the frequency response curve is flat, and whether the pitch of the sound is accurate.

[0003] The audio of an active speaker can be divided into extremely low frequency, low frequency, mid-low frequency, mid-frequency, mid-high frequency, high frequency and extremely high frequency. Among them, the extremely low frequency is between 20Hz and 40Hz, and this frequency band is also called the subwoofer. The speakers in this frequency band can express the low-frequency components of music, making the listeners feel a strong and powerful dynamic. The structure of the existing active subwoofer generally includes a box body, an active power amplifier and a speaker installed in the box body, etc. Under the mutual inductance of the voice coil of the speaker and the driving magnet, the diaphragm of the speaker makes a piston-like movement to generate sound waves, and the generated sound waves radiate outward to form sound; however, not all sound waves directly diffuse outward. Some sound waves will be sent to the listener's ears after cross-reflection on the diaphragm, that is, when the sound waves cross-reflect on the diaphragm, they are reflected from one side of the diaphragm to the other side and then to the listener's ears. Since these sound waves are generated at the same time but heard at different times, this causes standing wave distortion, which affects the smoothness of sound wave radiation and results in off-axis frequency response peak-valley phenomena often occurring in the speaker. To solve the problem of standing wave distortion, the prior art generally installs a phase plug at the dust cap in the center of the speaker or at the outer end of the speaker. For example, in the Chinese patent application with the publication number CN204425646U, the purpose of this phase plug is to make the sound waves reflected by the vibration of the speaker diaphragm contact the surface of the phase plug, and the surface of the phase plug emits the secondary reflected waves of the sound waves, shortening the delay time of sound wave emission, thereby reducing standing wave distortion. However, the standing wave distortion of the existing active subwoofer is still relatively serious, especially the intensity of the bass is not strong enough and the sound reproduction quality is poor. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the above prior art and provide an active subwoofer that can effectively reduce standing wave distortion, does not affect the smoothness of sound wave radiation, improves the compliance of the speaker unit, and has strong bass and high sound reproduction quality.

[0005] The technical solution of the present invention is to provide an active subwoofer having the following structure: It includes

[0006] a box body, which is hollow inside and has an inner cavity. An installation hole communicating with the inner cavity is provided at the bottom of the box body. A speaker unit is connected inside the inner cavity, and the outer end of the speaker frame of the speaker unit is connected in the installation hole. The opening of the conical paper cone inside the speaker frame is arranged downward.

[0007] a base, which is arranged below the box body and connected to the bottom of the box body. There is a radiation space between the base and the bottom of the box body for the sound wave of the speaker unit to radiate around. An active power amplifier is installed inside the base, and the active power amplifier is electrically connected to the speaker unit. A protruding part protruding upward is provided at the top of the base below the opening of the conical paper cone. The top of the protruding part extends upward through the opening of the conical paper cone and is arranged inside the conical paper cone. An annular compression cavity is formed between the outer side wall of the protruding part and the inner wall of the conical paper cone, and the periphery of the compression cavity is connected to the radiation space.

[0008] After adopting the above structure, compared with the prior art, the active ultra-low frequency sound of the present invention has the following advantages: First, the opening of the conical paper cone of the loudspeaker unit of the active ultra-low frequency sound is arranged downward. The sound waves generated by the loudspeaker unit are compressed with the top of the base in the radiation space and then radiate and spread outward from the periphery of the radiation space. Therefore, the sound is more powerful and has a deep bass; Second, the protruding part on the top of the base extends upward through the opening of the conical paper cone and is arranged inside the conical paper cone, and an annular compression cavity is formed between the outer side wall of the protruding part and the inner wall of the conical paper cone. Part of the sound waves reflected by the vibration of the conical paper cone enter the radiation space through the compression cavity and radiate and spread outward, and the other part of the sound waves contact the outer side wall of the protruding part. The outer side wall of the protruding part is equivalent to a phase plug. Therefore, the outer side wall of the protruding part quickly reflects the secondary reflected wave of the sound wave into the radiation space and radiates and spreads outward. In this way, the lag time of sound wave emission is reduced, the standing wave distortion is effectively reduced, and the sound reproduction quality is high; The arrangement of the protruding part extending into the conical paper cone compresses the sound radiation space inside the conical paper cone, effectively shortens the reflection time of the sound wave, and balances the air pressure in front of and behind the conical paper cone of the loudspeaker unit, further reducing sound distortion. Secondly, the present invention arranges the protruding part equivalent to a phase plug on the base. The protruding part extends into the conical paper cone, and an annular compression cavity is formed between the protruding part and the conical paper cone, that is, the lower end of the compression cavity is open and unobstructed; Compared with the prior art in which a columnar phase plug is arranged in the center of the conical paper cone, the protruding part completely separates the space inside the conical paper cone, thus completely avoiding the sound wave from being reflected from one side of the conical paper cone surface to the other side of the conical paper cone surface, effectively reducing the lag time of sound wave emission; Compared with the prior art in which a phase plug partially extending into the paper cone is installed at the outer end of the loudspeaker unit frame (see the Chinese patent application with the publication number CN204425646U), on the one hand, the sound wave is completely avoided from being reflected from one side of the conical paper cone surface to the other side of the conical paper cone surface, reducing the lag time of sound wave emission. On the other hand, the compression cavity formed between the protruding part and the inner wall of the conical paper cone can compress the reflected sound wave, making the bass effect more powerful. Moreover, the lower end of the compression cavity is completely open and unobstructed, which does not affect the smoothness of sound wave radiation, effectively improves the compliance of the loudspeaker unit, avoids the off-axis frequency response peak-valley phenomenon often occurring in the loudspeaker unit, and makes the tone pure and natural.

[0009] Preferably, the outer sidewall of the protruding portion is in a conical shape that is smaller at the top and larger at the bottom, and the taper of the outer sidewall of the protruding portion is the same as that of the inner wall of the conical paper cone, so that the distance between the outer sidewall of the protruding portion and the inner wall of the conical paper cone is the same. With this setting, the time difference of the sound waves reflected from different positions of the conical paper cone reaching the outer sidewall of the protruding portion is small, or the distance between the outer sidewall of the protruding portion and the inner wall of the conical paper cone is the same. Therefore, the sound waves reflected from the inner wall of the conical paper cone are transmitted in the annular compression space for the same time or with a small time difference, thereby further reducing the standing wave distortion and achieving high-quality sound reproduction.

[0010] Preferably, the outer sidewall of the dust cap at the center of the conical paper cone is set as a concave arc surface, and the top wall of the protruding portion is set as a convex arc surface, and the curvature of the top wall of the protruding portion is adapted to the curvature of the dust cap, so as to make the distance between the top wall of the protruding portion and the outer sidewall of the dust cap the same; the distance between the outer sidewall of the protruding portion and the inner wall of the conical paper cone is equal to the distance between the top wall of the protruding portion and the outer sidewall of the dust cap. With this setting, the width of the top of the annular compression cavity is consistent, and the width of the side part and the top of the annular compression cavity is consistent. Therefore, the space in the annular compression cavity is more uniform, the air thickness in the annular compression cavity is consistent, which can well balance the air pressure before and after the conical paper cone, and further reduce the delay time of sound wave emission, improving the compliance of the speaker unit.

[0011] Preferably, the projection of the opening of the conical paper cone in the vertical direction completely covers the protruding portion. With this setting, it is not only beneficial to the outward radiation and diffusion of the sound waves reflected by the conical paper cone, but also the sound waves that are not reflected from the surface of the conical paper cone can directly contact the outer sidewall of the protruding portion for secondary reflection and emission, further reducing the standing wave distortion and making the structure of the sound box more compact.

[0012] Preferably, the protruding portion and the top wall of the base are of an integrally formed structure, and a receiving cavity adapted to the shape of the protruding portion is formed on the back surface of the protruding portion. With this setting, since an active power amplifier and other control components are installed in the base, the setting of this receiving cavity increases the installation space in the base, facilitating the installation of the active power amplifier, control circuit board, etc. in the base, and also facilitating heat dissipation.

[0013] Preferably, a suction cup assembly is connected to the bottom of the base. This suction cup assembly improves the connection stability and firmness between the base of the active subwoofer and the ground, tabletop or desktop, avoiding shaking.

[0014] Preferably, a plurality of connecting columns are provided along the circumferential direction of the base and extending upward at the outer edge of the top of the base, and the top of the connecting column is connected to the bottom of the box body, so as to form the radiation space between the bottom of the box body and the top of the base. With this setting, the sound waves generated by the speaker unit can be radiated and diffused outward simultaneously around the bottom of the box body, thereby achieving good sound effects, higher and purer sound quality.

[0015] Preferably, a mounting bracket is connected in the inner cavity of the box body. The mounting bracket divides the inner cavity into two mutually communicating air cavities from bottom to top: a first air cavity and a second air cavity. The speaker unit is mounted on the mounting bracket, and the back of the conical paper cone of the speaker unit is located in the first air cavity. An air inlet and outlet hole communicating with the second air cavity is provided on the box body, and a phase inverter tube is connected in the second air cavity. The first end of the phase inverter tube communicates with the second air cavity, and the second end of the phase inverter tube is connected in the air inlet and outlet hole and communicates with the air inlet and outlet hole. As is well known, the main function of the phase inverter tube is to increase the low-frequency radiation energy of the sound. When the conical paper cone of the speaker unit vibrates, sound waves with opposite phases will be generated on the front and back sides. Among them, the direct sound waves generated on the front of the speaker unit will be directly radiated into the external space, while the sound waves generated on the back of the speaker will enter the phase inverter tube under the action of the pressure difference and be radiated into the external space through the second end of the phase inverter tube or the air inlet and outlet hole. The reverse sound waves generated on the back of the conical paper cone form reverse sound waves with the same phase as the direct sound waves after the action of the phase inverter tube, thereby enhancing the sound wave radiation and low-frequency sound reproduction ability. Therefore, the bass of this active subwoofer is more powerful and forceful, and the sound effect is good.

[0016] Preferably, the phase inverter tube is integrally arranged in an S shape, and the inner wall of the phase inverter tube has a smooth transition. The phase inverter tube arranged in an S shape not only has a longer length dimension in the limited box body space, but also compared with similar products, when the length of the phase inverter tube is the same, the volume of this box body can be made smaller. Moreover, the phase inverter tube arranged in an S shape can increase the overall length of the phase inverter tube as much as possible in one direction, improving the low-frequency dive of the phase inverter tube. Moreover, the smooth transition of the inner wall of the S-shaped phase inverter tube, especially at the turning points, is beneficial to reducing the wind noise between the air and the inner wall of the pipe, avoiding sound distortion and reducing sound coloring.

[0017] Preferably, the phase inverter tube sequentially includes a first straight tube portion, a first bent tube portion, a second straight tube portion, a second bent tube portion and a throat tube portion from inside to outside;

[0018] The inlet at the first end of the first straight tube portion communicates with the second air cavity. The second end of the first straight tube portion is tangent to and smoothly transitions with the first end of the first bent tube portion. The second end of the first bent tube portion is tangent to and smoothly transitions with the first end of the second straight tube portion. The second end of the second straight tube portion is tangent to and smoothly transitions with the first end of the second bent tube portion. The second end of the second bent tube portion smoothly transitions with the throat tube portion. Among them,

[0019] The included angle between the center line of the first straight tube portion and the center line of the second straight tube portion is 10 to 20 degrees. The first bent tube portion and the second bent tube portion are symmetrically arranged about the center of the second straight tube portion;

[0020] The throat part is in the shape of a horn with a smaller inner diameter and a larger outer diameter, and the outer end outlet of the throat part is communicated with the air inlet and outlet hole; and,

[0021] The outer end outlet of the throat part is located at the center of the width direction of the inverted phase tube. The S-shaped inverted phase tube arranged in this way has a compact structure. In one direction, the overall length of the inverted phase tube is longer, and the low-frequency dive of the sound wave in the inverted phase tube is deeper, thereby further enhancing the sound wave radiation and low-frequency sound reproduction ability; in addition, the connection between the first bent pipe part and the second bent pipe part and the first straight pipe part and the second straight pipe part is smooth, thereby further reducing the wind noise between the air and the inner wall of the pipe, avoiding sound distortion and reducing sound coloring. Moreover, the included angle between the center line of the first straight pipe part and the center line of the second straight pipe part is 10 to 20 degrees, and the first bent pipe part and the second bent pipe part are symmetrically arranged about the center of the second straight pipe part; the S-shaped inverted phase tube has a more compact structure, a smaller volume, and in the case where the overall width and length of the inverted phase tube remain unchanged, the length of the inverted phase tube in a single direction can be set longer. Brief Description of the Drawings

[0022] Figure 1 is a schematic structural diagram of an active ultra-low frequency sound box of the present invention.

[0023] Figure 2 is a front structural diagram of an active ultra-low frequency sound box of the present invention.

[0024] Figure 3 is a schematic assembled structural diagram of an active ultra-low frequency sound box of the present invention.

[0025] Figure 4 is a schematic assembled structural diagram of an active ultra-low frequency sound box of the present invention from another angle.

[0026] Figure 5 is a schematic sectional structural diagram of an active ultra-low frequency sound box of the present invention.

[0027] Figure 6 is a schematic sectional structural diagram of an active ultra-low frequency sound box in an assembled state of the present invention.

[0028] Figure 7 is a schematic structural diagram of an inverted phase tube of an active ultra-low frequency sound box of the present invention.

[0029] Figure 8 is a front structural diagram of an inverted phase tube of an active ultra-low frequency sound box of the present invention.

[0030] As shown in the figure:

[0031] 1. Cabinet, 100. Inner cavity, 101. Mounting hole, 102. Mounting bracket, 103. First air cavity, 104. Second air cavity, 105. Air inlet and outlet hole, 2. Base, 200. Protrusion, 201. Connecting column, 202. Switch, 203. Power socket, 204. Suction cup assembly, 205. Accommodation cavity, 206. Active power amplifier, 3. Radiation space, 4. Speaker unit, 400. Speaker frame, 401. Conical paper cone, 402. Dust cap, 5. Compression cavity, 6. Phase inverter, 600. First straight pipe, 601. Inlet, 602. First elbow section, 603. Second straight pipe, 604. Second elbow section, 605. Throat section, 606. Mounting flange. Detailed implementation manners

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] See Figures 1 to 8 as shown;

[0034] An embodiment of the present invention discloses an active ultra - low - frequency sound box, whose structure includes a cabinet 1 and a base 2 arranged below the cabinet 1 and connected to the bottom of the cabinet 1; the cabinet 1 is hollow inside and has an inner cavity 100, a mounting hole 101 communicating with the inner cavity 100 is provided at the bottom of the cabinet 1, a speaker unit 4 is connected inside the inner cavity 100, and the outer end of the speaker frame 400 of the speaker unit 4 is connected in the mounting hole 101, and the opening of the conical paper cone 401 inside the speaker frame 400 is arranged downward; the speaker unit 4 in this embodiment is an electro - acoustic transducer, and its structure generally includes a magnet, a speaker frame 400, a centering washer, a voice coil, a conical paper cone 401, etc. When an audio current passes through the voice coil in a magnetic field, a magnetic field changing with the audio current is generated. This magnetic field interacts with the magnetic field of the permanent magnet, causing the voice coil to vibrate axially, thereby causing the conical paper cone 401 to vibrate and emit sound. It is a product of the prior art and will not be described in detail in this embodiment. A plurality of connecting columns 201 distributed circumferentially along the base 2 and extending upward are provided at the outer edge of the top of the base 2, and the top of the connecting column 201 is connected to the bottom of the cabinet 1, so that there is a gap between the bottom of the cabinet 1 and the top of the base 2, and this gap forms a radiation space 3 for the sound waves of the speaker unit 4 to radiate around; in this embodiment, both the cabinet 1 and the base 2 are square - shaped. Therefore, four connecting columns 201 are provided at the four corners of the top of the base 2, and the radiation space 3 communicates with the outside through the gaps between the connecting columns 201, so that the sound waves of the speaker unit 4 can radiate and diffuse outward simultaneously from all around the radiation space 3; in other embodiments, the cabinet 1 and the base 2 can also be set to be cylindrical, polygonal, etc.

[0035] See Figure 4As shown, in this embodiment, since the mounting hole 101 is provided at the center of the bottom of the cabinet 1, the speaker unit 4 is vertically downward. The sound waves generated by the speaker unit 4 are compressed to a certain extent with the top of the base 2 in the radiation space 3 and then radiate and spread outward from the periphery of the radiation space 3. Therefore, the sound is more powerful, strong, and has a deep bass.

[0036] See Figures 3 to 5 As shown, in this embodiment, an active power amplifier 206 is installed in the base 2. The active power amplifier 206 is also an active power amplifier or an active power amplification circuit, and the active power amplifier 206 is electrically connected to the speaker unit 4; a switch 202 and a power plug 203 are provided on the base 2, and the power plug 203 is electrically connected to the active power amplifier 206; in other embodiments, a power supply can also be installed in the base 2; the switch 202 is used to control the operation of the active subwoofer; a protruding portion 200 protruding upward is provided on the top of the base 2 below the opening of the conical paper cone 401 of the speaker unit 4, and the top of the protruding portion 200 extends upward through the opening of the conical paper cone 401 and is disposed inside the conical paper cone 401; an annular compression cavity 5 is formed between the outer side wall of the protruding portion 200 and the inner wall of the conical paper cone 401, and the periphery of the compression cavity 5 is communicated with the radiation space 3. Part of the sound waves reflected by the vibration of the conical paper cone 401 of the speaker unit 4 enter the radiation space 3 through the compression cavity 5 and radiate and spread outward, and the other part of the sound waves contact the outer side wall of the protruding portion 200. The outer side wall of the protruding portion 200 is equivalent to a phase plug. Therefore, the outer side wall of the protruding portion 200 quickly reflects the secondary reflected wave of the sound wave into the radiation space 3 and radiates and spreads outward, which reduces the lag time of sound wave emission, effectively reduces the standing wave distortion, and has a high sound reproduction quality; the arrangement of the protruding portion 200 extending into the conical paper cone 401 compresses the sound radiation space 3 inside the conical paper cone 401, effectively shortens the reflection time of the sound wave, and balances the air pressure before and after the conical paper cone 401 of the speaker unit 4, further reducing the sound distortion.

[0037] See again Figure 5 and Figure 6As shown in the figure, the present invention provides a protrusion 200 equivalent to a phase plug on the base 2. The protrusion 200 extends into the conical diaphragm 401, and an annular compression cavity 5 is formed between the protrusion 200 and the conical diaphragm 401, that is, the lower end of the compression cavity 5 is open and unobstructed. Therefore, the cooperation structure between the protrusion 200 and the conical diaphragm 401 of the present invention, compared with the prior art where a stigma-shaped phase plug is provided at the center of the conical diaphragm 401, the protrusion 200 completely divides the space inside the conical diaphragm 401, thus completely avoiding the reflection of sound waves from one side of the surface of the conical diaphragm 401 to the other side, effectively reducing the lag time of sound wave emission. And compared with the prior art where a phase plug partially extending into the diaphragm is installed at the outer end of the speaker unit 4 chassis 400 (refer to the phase plug described in the Chinese patent application with the publication number CN204425646U), on the one hand, it completely avoids the reflection of sound waves from one side of the surface of the conical diaphragm 401 to the other side, reducing the lag time of sound wave emission. On the other hand, the compression cavity 5 formed between the protrusion 200 and the inner wall of the conical diaphragm 401 can compress the reflected sound waves, making the bass effect more powerful. Moreover, the lower end of the compression cavity 5 is completely open and unobstructed, which does not affect the smoothness of sound wave radiation, effectively improving the compliance of the speaker unit 4, avoiding the off-axis frequency response peak-valley phenomenon often occurring in the speaker unit 4, and making the tone pure and natural, maintaining the quality of the sound itself.

[0038] Refer again to Figure 5 As shown in the figure, in this embodiment, the outer wall of the protrusion 200 at the top of the base 2 is in the shape of a cone with a smaller upper part and a larger lower part, that is, the outer wall of the protrusion 200 is a conical surface, and the taper of the outer wall of the protrusion 200 is the same as the taper of the inner wall of the conical diaphragm 401, so that the distance between the outer wall of the protrusion 200 and the inner wall of the conical diaphragm 401 is the same. Further, the outer wall of the dust cap 402 at the center of the conical diaphragm 401 is set as a concave arc surface, and the top wall of the protrusion 200 is set as a convex arc surface, and the curvature of the top wall of the protrusion 200 is adapted to the curvature of the dust cap 402, so as to make the distance between the top wall of the protrusion 200 and the outer wall of the dust cap 402 the same. Moreover, in this embodiment, the distance between the outer wall of the protrusion 200 and the inner wall of the conical diaphragm 401 is equal to the distance between the top wall of the protrusion 200 and the outer wall of the dust cap 402. Therefore, the time difference of the reflected sound waves at different positions of the conical diaphragm 401 reaching the outer wall of the protrusion 200 is small, or the distance between the outer wall of the protrusion 200 and the inner wall of the conical diaphragm 401 is the same, making the space in the annular compression cavity more uniform, the air thickness in the annular compression cavity consistent, which can well balance the air pressure before and after the conical diaphragm 401, and further reduce the lag time of sound wave emission, improving the compliance of the speaker unit 4; thereby further reducing the standing wave distortion and having a high sound reproduction quality.

[0039] In this embodiment, the projection of the opening of the conical paper cone 401 in the vertical direction completely covers the protruding portion 200, that is, the protruding portion 200 is located within the projection of the opening of the conical paper cone 401 in the vertical direction. This not only facilitates the outward radiation and diffusion of the sound waves reflected by the conical paper cone 401, but also enables the sound waves that are not reflected from the surface of the conical paper cone 401 to directly contact the outer wall of the protruding portion 200 for secondary reflection and emission, further reducing the standing wave distortion and making the structure of the sound box more compact.

[0040] In this embodiment, the protruding portion 200 and the top wall of the base 2 are of an integrally formed structure, and a receiving cavity 205 adapted to the shape of the protruding portion 200 is formed on the back surface of the protruding portion 200. Since electronic components such as an active power amplifier 206 and a control circuit board are installed in the base 2, the provision of the receiving cavity 205 increases the installation space in the base 2, facilitates the installation of the active power amplifier 206, the control circuit board and other electronic components in the base 2, and also facilitates the heat dissipation of the electronic components.

[0041] Refer again to Figure 2 and Figure 4 As shown, it can be understood that in order to improve the stability and firmness of the connection between the base 2 of the active subwoofer sound box and the ground, tabletop or desktop and avoid shaking. A suction cup assembly 204 is connected to the bottom of the base 2, and the suction cup assembly 204 includes a plurality of suction cups connected to the bottom of the base 2.

[0042] Refer again to Figure 5 and Figure 6As shown, as an embodiment of the present invention; an installation bracket 102 is connected in the inner cavity 100 of the box body 1. The installation bracket 102 divides the inner cavity 100 into two mutually communicating air cavities from bottom to top: a first air cavity 103 and a second air cavity 104. The speaker unit 4 is installed on the installation bracket 102, and the back of the conical paper cone 401 of the speaker unit 4 is located in the first air cavity 103. An air inlet and outlet hole 105 communicating with the second air cavity 104 is provided on the box body 1, and a phase inverter tube 6 is connected in the second air cavity 104. The first end of the phase inverter tube 6 communicates with the second air cavity 104, and the second end of the phase inverter tube 6 is provided with an installation flange 606. The installation flange 606 is connected to the inner end of the air inlet and outlet hole 105 to make the second end of the phase inverter tube 6 communicate with the air inlet and outlet hole 105. As is well known, when the conical paper cone 401 of the speaker unit 4 vibrates, sound waves with opposite phases are generated on its front and back. Among them, the direct sound waves generated on the front of the speaker unit 4 will be directly radiated into the external space, while the sound waves generated on the back of the speaker will enter the phase inverter tube 6 under the action of the pressure difference and be radiated into the external space through the second end of the phase inverter tube 6 or the air inlet and outlet hole 105. The reverse sound waves generated on the back of the conical paper cone 401 form reverse sound waves with the same phase as the direct sound waves after the action of the phase inverter tube 6, thereby enhancing the sound wave radiation and low-frequency sound reproduction ability. Therefore, the bass of this active subwoofer is more powerful and the sound effect is good.

[0043] See Figure 7 and Figure 8 As shown, in this embodiment; the phase inverter tube 6 is integrally arranged in an S shape, and the inner wall of the phase inverter tube 6 has a smooth transition. The phase inverter tube 6 arranged in an S shape can not only set a phase inverter tube 6 with a longer length dimension in the limited space of the box body 1, but also, compared with similar products, when the length of the phase inverter tube 6 is the same, the volume of the box body 1 can be made smaller; moreover, the phase inverter tube 6 arranged in an S shape can increase the overall length of the phase inverter tube 6 as much as possible in one direction, improving the low-frequency dive of the phase inverter tube 6, and the smooth transition of the inner wall of the S-shaped phase inverter tube 6, especially at the turning point, is beneficial to reducing the wind noise between the air and the inner wall of the pipeline, avoiding sound distortion and reducing sound coloration.

[0044] Further, in this embodiment, the inverted phase tube 6 sequentially includes a first straight tube portion 600, a first bent tube portion 602, a second straight tube portion 603, a second bent tube portion 604, and a throat tube portion 605 from inside to outside; an inlet 601 at the first end of the first straight tube portion 600 communicates with the second air cavity 104, the second end of the first straight tube portion 600 is tangent to and smoothly transitions to the first end of the first bent tube portion 602, the second end of the first bent tube portion 602 is tangent to and smoothly transitions to the first end of the second straight tube portion 603, the second end of the second straight tube portion 603 is tangent to and smoothly transitions to the first end of the second bent tube portion 604, and the second end of the second bent tube portion 604 smoothly transitions to the throat tube portion 605; the first straight tube portion 600, the first bent tube portion 602, the second straight tube portion 603, the second bent tube portion 604, and the throat tube portion 605 form the S-shaped inverted phase tube 6. In this embodiment, the cross-section of the inverted phase tube 6 is a rectangle with rounded corners; in other embodiments, the cross-section of the inverted phase tube 6 can also be circular, racetrack-shaped, etc. Further, the angle A between the centerlines of the first straight tube portion 600 and the second straight tube portion 603 of the inverted phase tube 6 is 10 to 20 degrees. In this embodiment, the angle A between the centerlines of the first straight tube portion 600 and the second straight tube portion 603 is 16 degrees; in this way, the second straight tube portion 603 is inclined relative to the first straight tube portion 600, and the first bent tube portion 602 and the second bent tube portion 604 are made more compact. Moreover, the first bent tube portion 602 and the second bent tube portion 604 are symmetrically arranged about the center of the second straight tube portion 603; the throat tube portion 605 is in the shape of a horn with a smaller inner diameter and a larger outer diameter, and the outer end outlet of the throat tube portion 605 communicates with the air inlet / outlet hole 105; in this embodiment, the outer end outlet of the throat tube portion 605 is located at the center in the width direction of the inverted phase tube 6. The S-shaped inverted phase tube 6 arranged in this way has a compact structure, the overall length of the inverted phase tube 6 is longer in one direction, the low-frequency dive of the sound wave in the inverted phase tube 6 is deeper, thereby further enhancing the sound wave radiation and low-frequency sound reproduction capabilities; coupled with the smooth connection between the first bent tube portion 602 and the second bent tube portion 604 and the first straight tube portion 600 and the second straight tube portion 603, the wind noise between the air and the inner wall of the pipe is further reduced, avoiding sound distortion and reducing sound coloring. When the overall width and length of the inverted phase tube 6 remain unchanged, the length of the inverted phase tube 6 in a single direction can be set longer. In this embodiment, the overall width of the inverted phase tube 6 refers to the distance between the outer edges of the first bent tube portion 602 and the second bent tube portion 604; the overall length of the inverted phase tube 6 refers to the distance between the first end of the first straight tube portion 600 and the second end of the throat tube portion 605.

[0045] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. An active ultra-low frequency sound system, characterized in that: Including a box body, which is hollow inside and has an inner cavity. An installation hole communicating with the inner cavity is provided at the bottom of the box body. A speaker unit is connected inside the inner cavity, and the outer end of the speaker frame of the speaker unit is connected in the installation hole. The opening of the conical paper cone inside the speaker frame is arranged downward; a base, which is arranged below the box body and connected to the bottom of the box body. There is a radiation space between the base and the bottom of the box body for the sound wave of the speaker unit to radiate around. An active power amplifier is installed inside the base, and the active power amplifier is electrically connected to the speaker unit. A protruding part protruding upward is provided at the top of the base below the opening of the conical paper cone. The top of the protruding part extends upward through the opening of the conical paper cone and is arranged inside the conical paper cone, for separating the space inside the conical paper cone to prevent the sound wave from reflecting from one side of the surface of the conical paper cone to the other side. An annular compression cavity is formed between the outer side wall of the protruding part and the inner wall of the conical paper cone, and the four sides of the compression cavity are connected to the radiation space; an installation bracket is connected in the inner cavity of the box body. The installation bracket divides the inner cavity into two mutually communicating air cavities from bottom to top: a first air cavity and a second air cavity. The speaker unit is installed on the installation bracket, and the back of the conical paper cone of the speaker unit is located in the first air cavity. An air inlet and outlet hole communicating with the second air cavity is provided on the box body, and a phase inverter tube is connected inside the second air cavity. The first end of the phase inverter tube is connected to the second air cavity, and the second end of the phase inverter tube is connected to the air inlet and outlet hole; 2. The active ultra-low frequency sound box according to claim 1, wherein: the outer side wall of the protruding part is in a conical shape with a smaller top and a larger bottom, and the taper of the outer side wall of the protruding part is the same as the taper of the inner wall of the conical paper cone, so that the distance between the outer side wall of the protruding part and the inner wall of the conical paper cone is the same; 3. The active ultra-low frequency sound box according to claim 2, characterized in that: the outer side wall of the dust cap at the center of the conical paper cone is set as an inwardly concave arc surface, the top wall of the protruding part is set as an upwardly convex arc surface, and the radian of the top wall of the protruding part is adapted to the radian of the dust cap, for making the distance between the top wall of the protruding part and the outer side wall of the dust cap the same; the distance between the outer side wall of the protruding part and the inner wall of the conical paper cone is equal to the distance between the top wall of the protruding part and the outer side wall of the dust cap; 4. The active ultra-low frequency sound box according to claim 2, wherein: the projection of the opening of the conical paper cone in the vertical direction completely covers the protruding part; 5. An active ultra-low frequency sound device according to any one of claims 1 to 4, characterized in that: the protruding part and the top wall of the base are of an integrally formed structure, and a receiving cavity adapted to the shape of the protruding part is formed on the back of the protruding part; 6. The active ultra-low frequency sound box according to claim 5, characterized in that: a suction cup assembly is connected to the bottom of the base; 7. An active ultra-low frequency sound system according to claim 1, characterized in that: a plurality of connecting columns distributed along the circumference of the base and extending upward are provided at the outer edge of the top of the base. The top of the connecting column is connected to the bottom of the box body, so that the radiation space is formed between the bottom of the box body and the top of the base; 8. An active ultra-low frequency sound system according to claim 1, characterized in that: the second end of the phase inverter tube is connected in the air inlet and outlet hole; 9. An active ultra-low frequency sound system according to claim 8, characterized in that: the whole phase inverter tube is arranged in an S shape, and the inner wall of the phase inverter tube has a smooth transition; 10. An active ultra-low frequency sound device according to claim 9, characterized in that: the phase inverter tube successively includes a first straight tube part, a first bent tube part, a second straight tube part, a second bent tube part and a throat tube part from inside to outside; The inlet at the first end of the first straight pipe portion is communicated with the second air cavity. The second end of the first straight pipe portion is tangent to and smoothly transitions with the first end of the first bent pipe portion. The second end of the first bent pipe portion is tangent to and smoothly transitions with the first end of the second straight pipe portion. The second end of the second straight pipe portion is tangent to and smoothly transitions with the first end of the second bent pipe portion. The second end of the second bent pipe portion smoothly transitions with the throat pipe portion. Among them, The included angle between the center line of the first straight pipe portion and the center line of the second straight pipe portion is 10 to 20 degrees. The first bent pipe portion and the second bent pipe portion are symmetrically arranged about the center of the second straight pipe portion. The throat pipe portion is in the shape of a horn with a smaller inner diameter and a larger outer diameter, and the outer end outlet of the throat pipe portion is communicated with the air inlet and outlet hole. And, The outer end outlet of the throat pipe portion is located at the center in the width direction of the phase inverter pipe.

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