A bass speaker realizing cardioid directional radiation

Abstract

The invention discloses a bass speaker box for realizing cardioid radiation, comprising a shell, and also comprising a direct-phase inverted bass speaker unit and a sixth-order bandpass bass speaker unit arranged in the shell, wherein the direct-phase inverted bass speaker unit is located in front of the sixth-order bandpass bass speaker unit and the sound source radiation ports of the two are in opposite directions; the acoustic distance between the sound source radiation ports of the two is equal to 1 / 4 wavelength of the front cavity tuning frequency of the sixth-order bandpass bass speaker unit; the direct-phase inverted bass speaker unit and the sixth-order bandpass bass speaker unit are connected with reverse polarity. The bass speaker box realizes ultra-low frequency cardioid radiation by combining the direct-phase inverted speaker unit and the sixth-order bandpass speaker unit, does not need to use a digital signal processor for delay processing, and only needs to be externally connected to one power amplifier channel, which greatly reduces the complexity and cost of the device.

Description

Technical Field

[0001] The invention relates to the technical field of directional ultra-low frequency speakers, and in particular to a bass speaker that realizes cardioid directional radiation. Background Art

[0002] Common bass often presents a spherical radiation pattern because the wavelength of the bass band is longer than the size of the sound source. There are two existing ways to achieve cardioid directivity. One is to add a horn to the sound source to achieve directivity control. However, the more practical small horns all work in the mid-high frequency band. In the mid-low frequency band below 500Hz, the horn size must be larger than a wavelength of 500Hz (0.686 meters) or larger (100Hz wavelength is 3.43 meters). This makes the horn method of controlling the directivity of the low-frequency sound source not practical in reality. The second is that two independent power amplifier channels and two independent digital signal processor channels are required for delay processing. For example, the technical solution disclosed in patent CN201315664Y-a cardioid directivity speaker requires two independent drive circuits to drive the front speaker unit and the rear speaker unit respectively, and two independent drive circuits are used for delay processing. Two power amplifier channels are also required, and the speaker structure is complex and the cost is too high. Summary of the invention

[0003] In order to overcome the shortcomings of the prior art, one of the objects of the present invention is to provide a subwoofer that realizes cardioid directional radiation. It realizes ultra-low frequency cardioid directional radiation through the combination of a direct bass reflex speaker unit and a sixth-order bandpass speaker unit. It does not require the use of a digital signal processor for delay processing and only requires an external power amplifier channel, which greatly reduces the complexity and cost of the equipment.

[0004] One of the purposes of the present invention is achieved by the following technical solution:

[0005] A bass speaker box for realizing cardioid directional radiation comprises a shell, and also comprises a direct-fired bass reflex unit and a sixth-order band-pass bass speaker unit arranged in the shell, wherein the direct-fired bass reflex unit is located in front of the sixth-order band-pass bass speaker unit, and the sound source radiation ports of the direct-fired bass reflex unit and the sixth-order band-pass bass speaker unit are in opposite directions; the acoustic distance between the sound source radiation port of the direct-fired bass reflex unit and the sound source radiation port of the sixth-order band-pass bass speaker unit is equal to 1 / 4 wavelength of the front cavity tuning frequency of the sixth-order band-pass bass speaker unit; the direct-fired bass reflex unit is connected to the sixth-order band-pass bass speaker unit with reverse polarity.

[0006] Furthermore, it also includes a single-channel power amplifier driving unit, and the direct-fired bass speaker unit and the sixth-order bandpass bass speaker unit are driven by the single-channel power amplifier driving unit at the same time.

[0007] Furthermore, the direct-fired bass reflex speaker unit and the sixth-order bandpass bass speaker unit are connected in parallel with opposite polarities, and the single-channel power amplifier driving unit is electrically connected to the direct-fired bass reflex speaker unit and the sixth-order bandpass bass speaker unit respectively.

[0008] Further, the direct-fired bass reflex unit and the sixth-order bandpass bass speaker unit are connected in series with reverse polarity, the single-channel power amplifier driving unit is electrically connected to the direct-fired bass reflex unit and the direct-fired bass reflex unit is connected to the sixth-order bandpass bass speaker unit, or the single-channel power amplifier driving unit is electrically connected to the sixth-order bandpass bass speaker unit and the sixth-order bandpass bass speaker unit is connected to the direct-fired bass reflex unit.

[0009] Furthermore, the direct-fired bass speaker units have two.

[0010] Furthermore, there are two sixth-order bandpass bass speaker units.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] The bass speaker box realizing cardioid radiation is used in combination with a direct-fired bass reflex speaker unit and a sixth-order bandpass speaker unit, and the acoustic distance between the sound source radiation port of the direct-fired bass reflex speaker unit and the sound source radiation port of the sixth-order bandpass bass speaker unit is adjusted to be equal to 1 / 4 wavelength of the front cavity tuning frequency of the sixth-order bandpass bass speaker unit, so that the sound waves on the back of the bass speaker box are canceled and the sound waves on the front are superimposed, thereby realizing ultra-low frequency cardioid radiation; the bass speaker box realizing cardioid radiation does not need to use a digital signal processor for delay processing, and only needs to be externally connected to one power amplifier channel, which greatly reduces the complexity and cost of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A schematic structural diagram of a bass speaker box for realizing cardioid directional radiation provided by the present invention;

[0014] Figure 2 A waveform diagram of the sound waves emitted by a direct-phase inverted speaker unit and a sixth-order bandpass speaker unit at 8 meters in front of a bass speaker that realizes cardioid directional radiation provided by the present invention at 50Hz;

[0015] Figure 3A waveform diagram of the mixing of the sound waves of a direct-phase reflex speaker unit and a sixth-order bandpass speaker unit at 8 meters in front of a bass speaker that realizes cardioid directional radiation provided by the present invention at 50Hz;

[0016] Figure 4 A waveform diagram of the sound waves emitted by a direct-phase inverted speaker unit and a sixth-order bandpass speaker unit at 8 meters in front of a bass speaker that realizes cardioid directional radiation provided by the present invention at 80Hz;

[0017] Figure 5 A waveform diagram of a bass speaker that realizes cardioid radiation provided by the present invention after the sound waves of a direct-phase reflex speaker unit and a sixth-order bandpass speaker unit are mixed at 8 meters in front of the speaker at 80Hz;

[0018] Figure 6 A waveform diagram of the sound waves emitted by a direct-phase inverted speaker unit and a sixth-order bandpass speaker unit at 8 meters in front of a bass speaker that realizes cardioid directional radiation provided by the present invention at 100 Hz;

[0019] Figure 7 A waveform diagram of a bass speaker that realizes cardioid radiation provided by the present invention after the sound waves of a direct-phase reflex speaker unit and a sixth-order bandpass speaker unit are mixed at 8 meters in front of the speaker at 100Hz;

[0020] Figure 8 A waveform diagram of the sound waves emitted by a direct-phase inverted speaker unit and a sixth-order bandpass speaker unit at 8 meters behind a bass speaker that realizes cardioid directional radiation provided by the present invention at 50Hz;

[0021] Fig. 9 A waveform diagram of the sound waves emitted by a direct-phase inverted speaker unit and a sixth-order bandpass speaker unit at 8 meters behind a bass speaker that realizes cardioid directional radiation provided by the present invention at 80Hz;

[0022] Fig.10 A waveform diagram of the sound waves emitted by a direct-phase inverted speaker unit and a sixth-order bandpass speaker unit at 8 meters behind a bass speaker that realizes cardioid directional radiation provided by the present invention at 100 Hz;

[0023] Fig.11 A waveform diagram of a bass speaker that realizes cardioid radiation provided by the present invention after mixing the sound waves of a direct-inverted speaker unit and a sixth-order bandpass speaker unit 8 meters behind the speaker at 50, 80 and 100 Hz respectively;

[0024] Fig.12To simulate the frequency response diagram of a bass speaker that realizes cardioid directional radiation provided by the present invention at 8 meters in front and behind using EASE FOCUS 3 acoustic simulation software;

[0025] Fig.13 The schematic diagram of the sound wave radiation at 100 Hz of a bass speaker realizing cardioid directional radiation provided by the present invention is simulated by using EASE FOCUS 3 acoustic simulation software. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0027] See also Figure 1 , a bass speaker for realizing cardioid directional radiation, comprising a shell, a stainless steel screen is also provided on the surface of the shell, and also comprising a direct-fired bass speaker unit and a sixth-order band-pass bass speaker unit arranged in the shell, the direct-fired bass speaker unit is located in front of the sixth-order band-pass bass speaker unit and the sound source radiation ports of the direct-fired bass speaker unit and the sixth-order band-pass bass speaker unit are in opposite directions; the acoustic distance between the sound source radiation port of the direct-fired bass speaker unit and the sound source radiation port of the sixth-order band-pass bass speaker unit is equal to 1 / 4 wavelength of the front cavity tuning frequency of the sixth-order band-pass bass speaker unit; the direct-fired bass speaker unit is connected to the sixth-order band-pass bass speaker unit with reverse polarity.

[0028] The bass speaker box realizing cardioid radiation is used in combination with a direct-fired bass reflex speaker unit and a sixth-order bandpass speaker unit, and the acoustic distance between the sound source radiation port of the direct-fired bass reflex speaker unit and the sound source radiation port of the sixth-order bandpass bass speaker unit is adjusted to be equal to 1 / 4 wavelength of the front cavity tuning frequency of the sixth-order bandpass bass speaker unit, so that the sound waves on the back of the bass speaker box are canceled and the sound waves on the front are superimposed, thereby realizing ultra-low frequency cardioid radiation; the bass speaker box realizing cardioid radiation does not need to use a digital signal processor for delay processing, and only needs to be externally connected to one power amplifier channel, which greatly reduces the complexity and cost of the equipment.

[0029] As a preferred embodiment, a single-channel power amplifier driving unit is further included, and the direct-fired phase-reflex bass speaker unit and the sixth-order bandpass bass speaker unit are simultaneously driven by the single-channel power amplifier driving unit. By adding a single-channel power amplifier driving unit, the bass speaker box becomes an active speaker box without the need for an external power amplifier driver.

[0030] As a preferred embodiment, the direct-fired phase-inverted bass speaker unit and the sixth-order band-pass bass speaker unit are connected in parallel with reverse polarity, and the single-channel power amplifier driving unit is electrically connected to the direct-fired phase-inverted bass speaker unit and the sixth-order band-pass bass speaker unit, respectively. In addition, as a variant embodiment, the direct-fired phase-inverted bass speaker unit and the sixth-order band-pass bass speaker unit can also be connected in series with reverse polarity, the single-channel power amplifier driving unit is electrically connected to the direct-fired phase-inverted bass speaker unit and the direct-fired phase-inverted bass speaker unit is connected to the sixth-order band-pass bass speaker unit, or the single-channel power amplifier driving unit is electrically connected to the sixth-order band-pass bass speaker unit and the sixth-order band-pass bass speaker unit is connected to the direct-fired phase-inverted bass speaker unit.

[0031] As a preferred embodiment, the direct-fired bass reflex speaker units have two, and the sixth-order bandpass bass speaker units have two. It should be noted that the direct-fired bass reflex speaker units and the sixth-order bandpass bass speaker units can be one each, or two or more each.

[0032] See also Figure 1 , set the direct-firing bass reflex speaker unit as A, the sixth-order bandpass bass speaker unit as B, the acoustic distance between the radiation ports of the two speaker units AB is L = 0.86 m (equal to 1 / 4 wavelength of the front cavity tuning frequency of the sixth-order bandpass bass speaker unit), the phase of the sound emitted by A to 8 meters in front of the bass speaker is ΦFA, and the phase of the sound emitted by A to 8 meters behind the bass speaker is ΦRA; the phase of the sound emitted by B to 8 meters in front of the bass speaker is ΦFB, and the phase of the sound emitted by B to 8 meters behind the bass speaker is ΦRB.

[0033] When the acoustic distance L between them is 0.86 meters, the original phase difference between A and B is 1 / 4 wavelength, the phase of the direct-inverted bass speaker unit A is 0 degrees at 100Hz, and when the front cavity tuning frequency of the sixth-order bandpass bass speaker unit B is 100Hz, the phase of the sixth-order bandpass bass speaker unit B at 100HZ is 90 degrees, that is, a phase shift of 90 degrees. In addition, the driving signal of the B unit is 180 degrees inverted relative to the driving signal of the A unit, because the A and B units are connected with reverse polarity.

[0034] With the above structural setting, the sound obtained 8 meters in front of the bass speaker should be the superposition of unit A and unit B. The following is a calculation example at each frequency in the low frequency band:

[0035] 1. At 50HZ, ΦFA is 0 degrees, and the 50HZ phase ΦRA of the sound of unit B 8 meters in front of the subwoofer is: 180 degrees (reverse polarity connection) + 45 degrees (2.5 milliseconds delay caused by the difference in sound distance of 0.86 meters between the units) + 45 degrees (phase shift caused by the sixth-order bandpass bass speaker unit) = 270 degrees. The phase difference between the two is: 270 degrees - 0 degrees = 270 degrees. The signals of the same sound level with a phase difference of 270 degrees are superimposed by 3.01DB.

[0036] 2. At 80HZ, ΦFA is 0 degrees, and the 80HZ phase ΦRA of the sound of unit B to the front of the subwoofer at 8 meters is: 180 degrees (reverse polarity connection) + 72 degrees (2.5 milliseconds delay caused by the difference in sound distance of 0.86 meters between the units) + 72 degrees (phase shift caused by the sixth-order bandpass bass speaker unit) = 324 degrees. The phase difference between the two is: 324 degrees - 0 degrees = 324 degrees. The signals of the same sound level with a phase difference of 324 degrees are superimposed by 5.58DB.

[0037] 3. At 100HZ, ΦFA is 0 degrees, and the 100HZ phase ΦRA of the sound of unit B 8 meters in front of the subwoofer is: 180 degrees (reverse polarity connection) + 90 degrees (2.5 milliseconds delay caused by the difference in sound distance of 0.86 meters between units) + 90 degrees (phase shift caused by the sixth-order bandpass bass speaker unit) = 360 degrees, which means that the two sounds are superimposed in phase by 6.02DB.

[0038] At 8 meters behind the bass group, the sounds from the front and rear units should cancel each other out. The following is an example of calculations for different frequencies in the low frequency band:

[0039] 1. At 50HZ, the phase ΦRA of the sound emitted by unit A when it reaches 8 meters behind the bass group should be: 0 degrees + 45 degrees (the delay of 2.5 milliseconds caused by the difference in sound distance of 0.86 meters between the units) = 45 degrees, and the phase ΦRB of the sound emitted by unit B when it reaches 8 meters behind should be: 180 degrees (reverse polarity connection) + 45 degrees (phase shift caused by the sixth-order bandpass bass speaker unit) = 225 degrees, 225 degrees - 45 degrees = 180 degrees. The phase difference between the two sounds is 180 degrees, and the sound level after the two sounds are mixed is -∞.

[0040] 2. At 80HZ, the phase ΦRA of the sound emitted by unit A when it reaches 8 meters behind the bass group should be: 0 degrees + 72 degrees (the delay of 2.5 milliseconds caused by the sound distance difference of 0.86 meters between the units) = 72 degrees, and the phase ΦRB of the sound emitted by unit B when it reaches 8 meters behind should be: 180 degrees + 72 degrees (the phase shift caused by the sixth-order bandpass bass speaker unit) = 252 degrees, 252 degrees - 72 degrees = 180 degrees. The phase difference between the two sounds is 180 degrees, and the sound level after the two sounds are mixed is -∞.

[0041] 3. At 100HZ, the phase ΦRA of the sound emitted by unit A when it reaches 8 meters behind the bass group should be: 0 degrees + 90 degrees (the delay of 2.5 milliseconds caused by the sound distance difference of 0.86 meters between the units) = 90 degrees, and the phase ΦRB of the sound emitted by unit B when it reaches 8 meters behind should be: 180 degrees + 90 degrees (the phase shift caused by the sixth-order bandpass bass speaker unit) = 270 degrees, 270 degrees - 90 degrees = 180 degrees. The phase difference between the two sounds is 180 degrees, and the sound level after the two sounds are mixed is -∞.

[0042] The following is a table of calculation results for the calculation examples at various frequencies mentioned above.

[0043]

[0044] At the above frequencies, the waveforms of the sounds emitted by the A unit and the B unit at 8 meters before and after the bass speaker and the waveform of the mixed sounds are as follows: Figures 2 to 11 shown.

[0045] The method for calculating the sound intensity after the sound emitted by unit A and unit B is mixed is as follows:

[0046] The conversion formula between phase and delay is: Phase angle = frequency * time * 360. The phase angle of the same delay is different for different frequencies. For example, the phase angle of 2.5 milliseconds for 50HZ is: 50*0.0025*360=45 degrees, the phase angle of 2.5 milliseconds for 80HZ is: 80*0.0025*360=72 degrees, and the phase angle of 2.5 milliseconds for 100HZ is: 100*0.0025*360=90 degrees.

[0047] When two audio signals of the same level or sounds of the same sound pressure are mixed, the phase angle difference between them can lead to superposition or cancellation. The calculation formula is:

[0048] DB=(10)*(LOG(0.0000000001+2*(1+COS(RADIANS(angle))))),

[0049] For example: for a phase difference of 0 degrees, the number of DBs that the sound pressure increases is: 10*LOG(0.0000000001+2*(1+1)=6.02DB; for a phase difference of 180 degrees, the number of DBs that the sound pressure increases is: 10*LOG(0.0000000001+2*(1+COS3.14)=-∞DB; for a phase difference of 270 degrees, the number of DBs that the sound pressure increases is: 10*LOG(0.0000 000001+2*(1+COS4.71)=3.01DB; for a phase difference of 360 degrees, the number of DBs by which the sound pressure increases is: 10*LOG(0.0000000001+2*(1+COS6.28)=6DB; for a phase difference of 324 degrees, the number of DBs by which the sound pressure increases is: 10*LOG(0.0000000001+2*(1+COS5.65)=5.58DB.

[0050] Fig.12 The frequency response diagram of a bass speaker for realizing cardioid directional radiation provided by the present invention at 8 meters front and back is simulated using EASE FOCUS 3 acoustic simulation software. It can be seen from the figure that the average sound pressure difference of the bass band at the same distance front and back can reach more than 20dB, which effectively realizes the directional control of the bass. Fig.13 A schematic diagram of the sound wave radiation at 100 Hz of a bass speaker that realizes cardioid directional radiation provided by the present invention is simulated using EASE FOCUS 3 acoustic simulation software. It can be seen from the figure that the sound wave radiation of the bass speaker provided by the present invention is cardioid.

[0051] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A bass speaker for achieving cardioid directional radiation, comprising a housing, characterized in that: It also includes a direct-phase bass speaker unit and a sixth-order band-pass bass speaker unit arranged in the shell, wherein the direct-phase bass speaker unit is located in front of the sixth-order band-pass bass speaker unit and the sound source radiation ports of the direct-phase bass speaker unit and the sixth-order band-pass bass speaker unit are in opposite directions; the acoustic distance between the sound source radiation port of the direct-phase bass speaker unit and the sound source radiation port of the sixth-order band-pass bass speaker unit is equal to 1 / 4 wavelength of the front cavity tuning frequency of the sixth-order band-pass bass speaker unit; The direct-fired phase-reversed bass speaker unit is connected with the sixth-order bandpass bass speaker unit in reverse polarity.

2. The bass speaker for realizing cardioid radiation as claimed in claim 1, characterized in that: It also includes a single-channel power amplifier driving unit, and the direct-fired bass speaker unit and the sixth-order bandpass bass speaker unit are driven by the single-channel power amplifier driving unit at the same time.

3. The bass speaker for realizing cardioid radiation as claimed in claim 2, characterized in that: The direct-fired phase-inverted bass speaker unit is connected in parallel with the sixth-order bandpass bass speaker unit in reverse polarity, and the single-channel power amplifier driving unit is electrically connected to the direct-fired phase-inverted bass speaker unit and the sixth-order bandpass bass speaker unit respectively.

4. The bass speaker for realizing cardioid radiation as claimed in claim 2, characterized in that: The direct-fired bass reflex unit and the sixth-order bandpass bass speaker unit are connected in series with reverse polarity, the single-channel power amplifier driving unit is electrically connected to the direct-fired bass reflex unit and the direct-fired bass reflex unit is connected to the sixth-order bandpass bass speaker unit, or the single-channel power amplifier driving unit is electrically connected to the sixth-order bandpass bass speaker unit and the sixth-order bandpass bass speaker unit is connected to the direct-fired bass reflex unit.

5. The bass speaker for realizing cardioid radiation according to claim 1, characterized in that: The direct-firing bass speaker units include two.

6. The bass speaker for realizing cardioid radiation as claimed in claim 5, characterized in that: The number of the sixth-order bandpass bass speaker units is two.

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