Heart-shaped ultra-low frequency loudspeaker

Abstract

The utility model provides a heart type super low frequency loudspeaker, including box, built -in power amplifier module and digital audio processor, is provided with first cavity and second cavity who does not communicate each other in the box, installs two first bass unit and second bass unit who radiate to the front in first cavity, installs one third bass unit who radiate to the back in second cavity, through two acoustics completely independent cavity design, has eliminated the harmful acoustic coupling and pressure interference between front and back units physically, can realize deeper degree, purer sound energy suppression behind the sound box, has improved the ability of overcoming stage sound feedback and purifying stage environment, and the isolation of physical acoustics has avoided the intermodulation distortion produced between units through air medium, makes every unit can work linearly in its own cavity, can reduce the nonlinear distortion of system, improves the purity of tone.

Description

Technical Field

[0001] This utility model relates to the field of audio equipment technology, specifically to a cardioid ultra-low frequency loudspeaker. Background Technology

[0002] Subwoofer systems are a core component of modern professional audio systems, and their performance directly determines the low-frequency reproduction quality and impact of the entire system. However, traditional subwoofers mostly adopt an omnidirectional design, radiating enormous sound energy in all directions (including behind the stage).

[0003] In practical stage applications, this leads to significant technical drawbacks: the sound energy radiated backward strongly excites the reverberant sound field in the stage area, and when picked up by microphones on the stage (such as drum microphones and bass microphones), it easily causes acoustic feedback howling, severely limiting the usable gain of the entire sound reinforcement system; at the same time, excessive low-frequency energy accumulates in the stage area, resulting in a decrease in stage monitoring clarity and affecting the performance effect; in addition, radiation to useless areas is also a waste of energy.

[0004] To address these challenges, cardioid ultra-low frequency (ULF) technology has emerged. It achieves interference cancellation by generating a sound field at the rear of the speaker that is out of phase with the leaking sound waves at the front, thereby suppressing rear radiation. In existing technologies, a common implementation involves placing multiple radiating units (e.g., two at the front and one at the rear) within a common cavity, supplemented by electronic control.

[0005] However, this shared cavity design has inherent drawbacks: the sound pressure vibrations between the units couple and interfere with each other through the air medium within the cavity. This acoustic modulation leads to two major problems: first, it introduces nonlinear distortion, degrading sound quality; second, and more critically, it severely interferes with the precision of the electronic control system. The rear unit, acting as a cancellation source, is constrained by the pressure field changes generated by the front unit, causing its actual acoustic output to fail to maintain a linear and precise correspondence with the electrical control signal emitted by the DSP. As a result, the formation of cardioid directivity is disrupted, the rear sound wave cancellation effect is impure and superficial, and the ability to suppress stage-oriented energy is limited, failing to completely solve the problems of acoustic feedback and stage interference.

[0006] Therefore, there is an urgent need for a new type of ultra-low frequency loudspeaker system that can overcome acoustic interference between units, thereby providing a physical basis for achieving accurate and pure cardioid directivity. Utility Model Content

[0007] To address the shortcomings of existing technologies, this invention proposes a cardioid subwoofer, aiming to solve the problem of acoustic interference between units caused by the shared cavity design in existing cardioid subwoofers. This interference can cause nonlinear distortion and, in particular, severely degrade the accuracy and effectiveness of the electronic control system in achieving cardioid directivity, resulting in insufficient suppression of rear acoustic energy and an inability to completely eliminate stage acoustic feedback and interference.

[0008] The technical solution of this utility model is implemented as follows:

[0009] A cardioid subwoofer includes a cabinet, a built-in power amplifier module, and a digital audio processor. The cabinet contains a first cavity and a second cavity that are not interconnected. The first cavity houses two forward-radiating first and second woofers, and the second cavity houses a rearward-radiating third woofer. The digital audio processor controls the power amplifier module to provide the third woofer with an amplitude-attenuated and phase-reversed signal, causing the sound waves emitted by the third woofer to interfere and cancel out the sound waves radiated by the first and second woofers to the rear of the cabinet, thus forming a cardioid directional sound field.

[0010] Preferably, the first bass unit and the second bass unit form an angle θ, and 90°≤θ≤130°.

[0011] Preferably, the included angle θ is 114°.

[0012] Preferably, the two forward-radiating bass units together with the front panel of the cabinet form a compression acoustic structure; the rearward-radiating third bass unit together with the rear panel of the cabinet forms a planar waveguide acoustic structure.

[0013] Preferably, the first, second, and third bass units are all long-stroke 21-inch neodymium magnet bass units.

[0014] Preferably, the power amplifier module is a three-channel digital power amplifier module with a total power of 9000W, and the output terminals of its three channels are independently electrically connected to the first subwoofer, the second subwoofer, and the third subwoofer.

[0015] Preferably, the digital audio processor is a four-channel DSP processor, whose first and second output channels are respectively connected to the power amplifier channels driving the first and second subwoofers and are subjected to the same signal processing; its third output channel is connected to the power amplifier channel driving the third subwoofer and is subjected to independent signal processing, including amplitude attenuation and phase reversal, for working in conjunction with the two forward-facing subwoofers to form a cardioid sound field.

[0016] Preferably, the side of the enclosure is provided with a stacking connector for mechanical interlocking when multiple speakers are stacked vertically.

[0017] Preferably, the stacking connector includes a connecting plate, a slider, and a locking pin fixed to the side of the box. The upper part of the connecting plate has a vertical groove, the upper part of the groove has a first mounting hole, the lower part of the connecting plate has a second mounting hole, the slider is slidably disposed in the groove, and the upper and lower ends of the slider are respectively provided with an upper locking hole and a lower locking hole.

[0018] When two speakers are stacked, the upper locking hole of the slider aligns with the second mounting hole of the upper speaker connecting plate and is locked by a locking pin, while the lower locking hole of the slider aligns with the first mounting hole of the lower speaker connecting plate and is locked by another locking pin.

[0019] Compared with the prior art, the beneficial effects of this utility model are:

[0020] By employing a two acoustically completely independent cavity design, harmful acoustic coupling and pressure interference between the front and rear units are physically eliminated. This creates a clean, linear control environment for the digital audio processor. The digital audio processor can convert the amplitude attenuation and phase reversal signals emitted by the rear unit into precise acoustic output with virtually no distortion or interference, ensuring highly accurate cancellation of interference with sound waves leaking from the front unit to the rear. As a result, deeper and purer acoustic energy suppression is achieved at the rear of the speaker enclosure, enhancing the ability to overcome stage acoustic feedback and purify the stage environment. Furthermore, the physical acoustic isolation avoids intermodulation distortion between units through the air medium, allowing each unit to operate linearly within its own cavity, reducing system nonlinear distortion and improving sound purity. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the internal structure of the present invention;

[0022] Figure 2 This is the front view of the present invention;

[0023] Figure 3 This is a rear view of the present invention;

[0024] Figure 4 This is a schematic diagram of the stacked state of this utility model;

[0025] Figure 5 for Figure 4 A magnified structural diagram of point A in the middle.

[0026] Attached image labels:

[0027] 1-Enclosure; 11-First cavity; 12-Second cavity; 2-First bass unit; 3-Second bass unit; 4-Third bass unit; 5-Amplifier module; 6-Digital audio processor; 7-Stacking connector; 71-Connecting plate; 711-Slide groove; 712-First mounting hole; 713-Second mounting hole; 72-Slider; 721-Upper locking hole; 722-Lower locking hole; 73-Locking pin. Detailed Implementation

[0028] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0029] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0030] See Figures 1 to 3 A cardioid subwoofer includes a cabinet 1, a built-in power amplifier module 5, and a digital audio processor 6. The cabinet 1 has a first cavity 11 and a second cavity 12 that are not connected to each other. The first cavity 11 houses two forward-radiating first bass units 2 and second bass units 3, and the second cavity 12 houses a rearward-radiating third bass unit 4. The digital audio processor 6 controls the power amplifier module 5 to provide the third bass unit 4 with an amplitude-attenuated and phase-reversed signal, so that the sound waves emitted by the third bass unit 4 interfere with and cancel out the sound waves radiated by the first bass units 2 and second bass units 3 to the rear of the cabinet 1, thus forming a cardioid directional sound field.

[0031] The first cavity 11 and the second cavity 12 are two acoustically completely isolated and non-communicating cavities, physically eliminating harmful acoustic coupling and pressure interference between the front and rear units. This creates a clean and linear control environment for the digital audio processor 6. The digital audio processor 6 can convert the amplitude attenuation and phase reversal signals emitted by the rear unit into precise acoustic output with almost no distortion and interference, thereby ensuring highly accurate interference cancellation with sound waves leaking from the front unit to the rear. As a result, deeper and purer acoustic energy suppression is achieved at the rear of the speaker, improving the ability to overcome stage acoustic feedback and purify the stage environment. Moreover, the physical acoustic isolation avoids intermodulation distortion between units through the air medium, allowing each unit to operate linearly within its own cavity, effectively reducing nonlinear distortion of the system and improving sound purity.

[0032] See Figure 1 The two forward-radiating subwoofers, the first subwoofer 2 and the second subwoofer 3, are not placed parallel to each other; they are positioned at an angle θ, with 90°≤θ≤130°. This allows the sound waves emitted by the two units to better superimpose and couple within a predetermined area in front, enhancing the synergistic radiation efficiency. This angle helps control the coverage of the sound waves on the horizontal plane, preventing excessive energy dispersion or concentration. Moreover, this angle range is optimized to effectively avoid potential interference or directional distortion of sound waves caused by overly parallel unit installation or excessively large angles, ensuring a smooth and uniform forward sound pressure response.

[0033] Preferably, acoustic performance is better when the included angle θ is between 110° and 118°. In this preferred embodiment, after extensive acoustic simulation and experimental verification, the included angle θ is set to 114°. This value ensures that the sound waves generated by the two units achieve optimal coupling and superposition, maximizing forward radiation efficiency.

[0034] Two forward-radiating woofers, together with the front panel of cabinet 1, form a compression acoustic structure; a rearward-radiating third woofer 4, together with the rear panel of cabinet 1, forms a planar waveguide acoustic structure. The front compression structure improves the electro-acoustic conversion efficiency, essentially adding an "acoustic lever" to the unit, allowing it to push more air with the same input power, producing a higher sound pressure level and a more impactful low-frequency effect. It also helps to reduce the large amplitude nonlinear distortion of the control unit. The rear planar waveguide structure ensures that the phase response of the rear unit, as a "cancellation source," is more linear and flat. This allows the digital audio processor 6 to more accurately predict and control the sound waves it emits, thereby achieving deep and precise cancellation with the sound waves leaking from the front, resulting in a purer cardioid sound field.

[0035] Among them, the first bass unit 2, the second bass unit 3, and the third bass unit 4 are all long-stroke 21-inch neodymium magnet bass units. The large 21-inch diameter ensures a huge air-driving area, which is the foundation for producing extremely low-frequency sound; the long-stroke design means that the voice coil and diaphragm have a long linear displacement range, which can achieve large-amplitude piston movement without distortion under high power input, ensuring low-frequency resolution and dynamic performance at high sound pressure output; neodymium magnets have extremely high magnetic energy product, which can provide powerful driving force while significantly reducing the weight of the unit, thereby reducing the overall weight of the speaker cabinet, improving portability, and improving the transient response of the unit.

[0036] Specifically, amplifier module 5 is a three-channel digital amplifier module with a total power of 9000W. The output terminals of its three channels are independently electrically connected to the first subwoofer 2, the second subwoofer 3, and the third subwoofer 4, respectively. Each channel provides a dedicated and clean power output for each unit, avoiding mutual electrical interference caused by parallel or series connection between units. Moreover, the three-channel digital amplifier module 5 has the advantages of high efficiency, small size, light weight, and high control precision, making it very suitable for integration into active systems.

[0037] Specifically, the digital audio processor 6 is a four-channel DSP processor. Its first and second output channels are respectively connected to the power amplifier channels that drive the first bass unit 2 and the second bass unit 3, and the same signal processing is applied to them. Its third output channel is connected to the power amplifier channel that drives the third bass unit 4, and independent signal processing is applied to it. The independent signal processing includes amplitude attenuation and phase reversal, which are used to work in conjunction with the two forward-facing bass units to form a cardioid sound field.

[0038] The system's electrical signal flow and control principle are as follows: External audio signals are input to the built-in four-channel DSP processor. The DSP first performs frequency division and equalization on the input signal. Then, its first and second output channels carry the processed ultra-low frequency signals, with identical parameter settings (gain, EQ, delay, limiting). These two signals are sent to channels one and two of amplifier module 5, respectively. Amplifier module 5 is a three-channel digital amplifier with a total power of 9000W. Channels one and two independently drive the front subwoofer 2 and the second subwoofer 3, respectively. The DSP's third output channel carries another specially processed signal: this signal is attenuated by -6dB in amplitude and phase-reversed by 180° compared to the signals from channels one and two. This signal is sent to channel three of amplifier module 5 to drive the rear-facing third subwoofer 4. By adjusting the delay and amplitude parameters of the rear channel using DSP, it can be ensured that the sound waves generated by the rear unit and the sound waves leaking from the front unit in the area behind the speaker (especially the stage area) will interfere with each other and cancel each other out, thus forming a cardioid directional sound field.

[0039] See Figure 4 The side of the enclosure 1 is provided with a stacking connector 7, which is used for mechanical interlocking when multiple speakers are stacked one on top of the other.

[0040] For details, see Figure 5 The stacking connector 7 includes a connecting plate 71, a slider 72, and a locking pin 73. The connecting plate 71 is vertically mounted on the side of the enclosure 1. The upper part of the connecting plate 71 has a vertical groove 711. The upper end of the groove 711 and above it has a first mounting hole 712. The lower part of the connecting plate 71 has a second mounting hole 713. The slider 72 is slidably disposed in the groove 711. The two ends of the slider 72 have an upper locking hole 721 and a lower locking hole 722, respectively. When the two speakers are stacked, first align the connecting plate 71 at the bottom of the upper speaker with the connecting plate 71 at the top of the lower speaker, and then slide the connecting plate 71. Slider 72 is slid until its upper locking hole 721 and lower locking hole 722 are aligned with the second mounting hole 713 of the upper speaker and the first mounting hole 712 of the lower speaker, respectively. Then, a locking pin 73 is inserted into the first mounting hole 712 of the lower speaker and the lower locking hole 722 of slider 72, while another locking pin 73 is inserted into the second mounting hole 713 of the upper speaker and the upper locking hole 721 of slider 72, thus connecting and fixing the upper and lower speakers. This operation can securely lock the two speakers into a whole, which has the advantages of being fast, safe and reliable.

[0041] The working principle of this invention is as follows: Two units operating in independent compression chambers at the front efficiently and collaboratively radiate powerful ultra-low frequency sound energy towards the audience area. A unit operating in an independent chamber at the rear, under the precise control of the DSP and power amplifier, functions as an "active noise cancellation source." Its radiated sound waves, precisely amplitude and phase adjusted, cancel out the sound waves from the front units that inevitably diffract to the rear of the speaker enclosure. The end result is an enhanced sound pressure level in front of the speaker enclosure, while the sound pressure level behind it is greatly suppressed, creating a cardioid directional sound field. This not only projects energy more concentratedly and efficiently to the audience but also solves the problems of low-frequency reverberation excitation and microphone feedback on stage.

[0042] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A cardioid subwoofer, comprising a cabinet, a built-in power amplifier module, and a digital audio processor, characterized in that, The enclosure contains a first cavity and a second cavity that are not interconnected. The first cavity houses two forward-radiating subwoofers, and the second cavity houses a rearward-radiating subwoofer. The digital audio processor controls the power amplifier module to provide the third subwoofer with an amplitude-attenuated and phase-reversed signal, causing the sound waves emitted by the third subwoofer to interfere with and cancel out the sound waves radiated by the first and second subwoofers to the rear of the enclosure, thus forming a cardioid directional sound field.

2. The cardioid subwoofer according to claim 1, characterized in that, The first bass unit and the second bass unit form an angle θ between them, and 90°≤θ≤130°.

3. The cardioid subwoofer according to claim 2, characterized in that, The included angle θ is 114°.

4. The cardioid subwoofer according to claim 1, characterized in that, The two forward-radiating bass units together with the front panel of the enclosure form a compression acoustic structure; the rearward-radiating third bass unit together with the rear panel of the enclosure form a planar waveguide acoustic structure.

5. The cardioid subwoofer according to claim 1, characterized in that, The first, second, and third bass units are all long-stroke 21-inch neodymium magnet bass units.

6. The cardioid subwoofer according to claim 1, characterized in that, The power amplifier module is a three-channel digital power amplifier module with a total power of 9000W. The output terminals of its three channels are independently electrically connected to the first bass unit, the second bass unit, and the third bass unit, respectively.

7. The cardioid subwoofer according to claim 6, characterized in that, The digital audio processor is a four-channel DSP processor, whose first output channel and second output channel are respectively connected to the power amplifier channels that drive the first and second bass units, and apply the same signal processing. Its third output channel is connected to the power amplifier channel that drives the third woofer and applies independent signal processing, including amplitude attenuation and phase reversal, to work in conjunction with the two forward-facing woofers to form a cardioid sound field.

8. The cardioid subwoofer according to claim 1, characterized in that, The side of the enclosure is provided with a stacking connector for mechanical interlocking when multiple speakers are stacked vertically.

9. The cardioid subwoofer according to claim 8, characterized in that, The stacking connector includes a connecting plate, a slider, and a locking pin fixed to the side of the box. The upper part of the connecting plate has a vertical groove, the upper part of the groove has a first mounting hole, the lower part of the connecting plate has a second mounting hole, the slider is slidably disposed in the groove, and the upper and lower ends of the slider are respectively provided with an upper locking hole and a lower locking hole. When two speakers are stacked, the upper locking hole of the slider is aligned with the second mounting hole of the upper speaker connecting plate and locked by a locking pin, while the lower locking hole of the slider is aligned with the first mounting hole of the lower speaker connecting plate and locked by another locking pin.

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