A built-in reinforced domestic loudspeaker

Abstract

The application provides a kind of embedded reinforcement type domestic loudspeaker, including audio anti-common mode interference circuit, impedance matching circuit, low pass filter circuit, signal addition circuit, signal amplification circuit, loudspeaker output circuit;Audio anti-common mode interference circuit can prevent power frequency interference signal mixed into circuit, effectively filter out ship power voltage common mode interference;Impedance matching circuit can effectively prevent the occurrence of audio small signal transmission line signal reflection problem, filter out the superposition of signal, realize noise reduction;The application has the characteristics of self-controllable, embedded installation reinforcement, waterproof, low voltage, strong anti-interference ability, low failure rate, fast response speed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of reinforced loudspeakers, and particularly relates to an embedded reinforced domestic loudspeaker. BACKGROUND

[0002] The reinforced loudspeaker is installed in a ship display console, a multifunctional console, a fire control console and the like in an embedded manner as a ship output speech controlled device, and is a bridge for realizing man-machine voice interaction.

[0003] Therefore, the technical capability formed in the independent research and development process can guarantee national security, and is used for a national defense device, such as a previous reinforced loudspeaker, internal chips of which are mostly foreign chips, especially a main control chip, so that it is urgent to completely replace the non-domestic loudspeaker with a domestic chip to realize 100% domesticization of the ship voice device.

[0004] The previous ship output speech controlled device is as follows: on one hand, foreign commonly used chips are selected in circuit design, including resistors, capacitors and the like, so that the foreign chip manufacturers no longer produce similar types of chips, the control circuit needs to be modified, which increases manpower, material resources, reliability of the new type of circuit and the like, and on the other hand, the instability of the ship power supply will give the controlled device an input voltage interference signal, the interference signal on the device is diverse, the voltage glitch interference brought to the controlled device is particularly much, which will cause the speech distortion of the controlled device; the high humidity and high tide of the ship environment, the specific design of the structural design and the loudspeaker waterproof and the like. SUMMARY

[0005] To solve the above problems, the application provides an embedded reinforced domestic loudspeaker, which has the advantages of self-controllability, embedded installation reinforcement, waterproofness, low voltage, strong anti-interference capability, low failure rate and fast reaction speed.

[0006] An embedded reinforced domestic loudspeaker, comprising an audio common mode interference prevention circuit, an impedance matching circuit, a low-pass filter circuit, a signal addition circuit, a signal amplification circuit and a loudspeaker output circuit.

[0007] The audio common mode interference prevention circuit is used for filtering out common mode interference in left channel audio signals and right channel audio signals; the impedance matching circuit is used for preventing reflection of the audio signals after filtering out the common mode interference, filtering the superposition of the audio signals and realizing noise reduction of the audio signals; the low-pass filter circuit is used for filtering out high frequency interference signals in the audio signals after noise reduction; the signal addition circuit is used for mixing the audio signals of two channels after filtering out the high frequency interference signals; the signal amplification circuit is used for amplifying the mixed audio signals; and the loudspeaker output circuit is used for outputting the amplified audio signals.

[0008] Further, the audio common-mode interference prevention circuit is provided with an analog ground, a left channel input end, a right channel input end, a signal ground, a left channel output end and a right channel output end, wherein the signal ground and the analog ground are separately provided and not interconnected in the PCB.

[0009] Further, the signal addition circuit is implemented by using a GS8592 chip, and a KΩ level resistor is connected in series with a positive input end of a first channel of the GS8592 chip, and a resistor and a capacitor connected in parallel with each other are connected to an output end of the GS8592 chip.

[0010] Further, the signal amplification circuit is implemented by using an integrated chip EG8401, a resistor and a capacitor connected in parallel with each other are connected to an anti-distortion pin NCN of the integrated chip EG8401, and an adjustable resistor is connected in series with a channel input pin IN of the integrated chip EG8401, so that when the power of the audio signal is too large, the quality of the output audio signal can be adjusted by adjusting the size of the adjustable resistor.

[0011] Further, the audio common-mode interference prevention circuit comprises a left channel audio transformer U1 and a right channel audio transformer U2, wherein two ends of a primary coil of the left channel audio transformer U1 are respectively used as a left channel input end IN-L+ and an analog ground AGND, two ends of a secondary coil of the left channel audio transformer U1 are respectively used as a left channel output end INL+ and a signal ground GND, the left channel input end IN-L+ is connected to an original left channel audio signal, and the left channel output end INL+ outputs a left channel audio signal filtered from common-mode interference; two ends of a primary coil of the right channel audio transformer U2 are respectively used as a right channel input end IN-R+ and the analog ground AGND, two ends of a secondary coil of the right channel audio transformer U2 are respectively used as a right channel output end INR+ and the signal ground GND, the right channel input end IN-R+ is connected to an original right channel audio signal, and the right channel output end INR+ outputs a right channel audio signal filtered from common-mode interference.

[0012] The impedance matching circuit comprises a resistor R10 and a resistor R11, wherein the right channel audio signal filtered from common-mode interference is input into the low-pass filter circuit through the resistor R10 in series, and the left channel audio signal filtered from common-mode interference is input into the low-pass filter circuit through the resistor R11 in series.

[0013] The low-pass filter circuit comprises resistors R1-R4 and capacitors C1-C2, wherein one end of the resistor R1 is connected to the right channel audio signal filtered from noise and output by the resistor R10, the other end of the resistor R1 is connected to the signal addition circuit through the resistor R3 in series and the capacitor C1 in parallel, and the other end of the resistor R1 is grounded through the capacitor C1; one end of the resistor R2 is connected to the left channel audio signal filtered from noise and output by the resistor R11, the other end of the resistor R2 is connected to the signal addition circuit through the resistor R4 in series and the capacitor C2 in parallel, and the other end of the resistor R2 is grounded through the capacitor C2.

[0014] The signal adding circuit comprises a chip U4, resistors R5-R6 and a capacitor C3, wherein the chip U4 is composed of two same operational amplifiers, the two operational amplifiers are respectively used as a first channel and a second channel, the right channel audio signal filtered from high-frequency interference signals output by the resistor R3 and the left channel audio signal filtered from high-frequency interference signals output by the resistor R4 are connected to the reverse input end of the first channel, the forward input end of the first channel is connected with the resistor R6 in series, the output end of the first channel is connected with the mixed audio signal IN-OUT to the signal amplifying circuit, and the capacitor C3 and the resistor R5 are connected in parallel and then connected in series between the reverse input end and the output end of the first channel;

[0015] The signal amplifying circuit comprises a chip U3, resistors R7-R8 and capacitors C7-C9, wherein the mixed audio signal IN-OUT is connected to the channel input pin IN of the chip U3 after being connected with the resistor R8 and the capacitor C9 in series, the resistor R7 and the capacitor C8 are connected in parallel and then connected to the ground, the capacitor C7 is connected to the internal reference source pin BYPASS of the chip U3 and then connected to the ground, the power supply pin VDD of the chip U3 is connected with the power supply voltage output by the power supply, and the channel reverse phase output pin VON and the channel same phase output pin VOP of the chip U3 output the amplified audio signal;

[0016] The speaker output circuit comprises a socket CN2, the two channels of the socket CN2 receive the amplified audio signal output by the channel reverse phase output pin VON and the channel same phase output pin VOP respectively and then output the amplified audio signal to the designated speaker.

[0017] Further, the embedded reinforced domestic loudspeaker further comprises a power filter circuit I and a power filter circuit II.

[0018] The power filter circuit I is used for filtering the power supply voltage output by the power supply of the signal adding circuit, and the power filter circuit II is used for filtering the power supply voltage output by the power supply of the signal amplifying circuit.

[0019] Further, the power filter circuit I comprises a capacitor C4, wherein one end of the capacitor C4 is connected to the power supply voltage output by the power supply of the chip U4, and the other end is connected to the ground.

[0020] The power filter circuit II comprises a capacitor C6, wherein one end of the capacitor C6 is connected to the power supply voltage output by the power supply of the chip U3, and the other end is connected to the ground.

[0021] Further, the embedded reinforced localization loudspeaker also comprises a power supply voltage stabilizing circuit for stabilizing the power supply voltage of the signal amplification circuit, and the power supply voltage stabilizing circuit is composed of a capacitor C5, one end of the capacitor C5 is grounded, and the other end is connected to the power supply pin VDD of the chip U3.

[0022] Further, the signal amplification circuit is realized by using a domestic chip with the model EG8401; the signal addition circuit is realized by using a domestic chip with the model GS8592; the audio common-mode interference prevention circuit is realized by using a domestic chip with the model MX671R; the loudspeaker is also a domestic product; and the resistors and capacitors required for realizing other circuits are also selected from domestic military-grade products.

[0023] Beneficial effects:

[0024] 1. The embedded reinforced localization loudspeaker provided by the application comprises an audio common-mode interference prevention circuit, an impedance matching circuit, a low-pass filter circuit, a signal addition circuit, a signal amplification circuit and a loudspeaker output circuit.

[0025] 2. When left-channel and right-channel audio signals are simultaneously input into the audio transformers U1 and U2 of the audio common-mode interference prevention circuit, the front and rear stages of the audio transformers U1 and U2 effectively realize isolation, prevent the mixing of power frequency interference signals into the circuit, and especially when the ship power supply is unstable, the isolation effect is more obvious, thereby effectively filtering out the ship power voltage common-mode interference.

[0026] 3. The low-pass filter circuit of the embedded reinforced localization loudspeaker can effectively filter out high-frequency signals other than the set ones by selecting appropriate parameter resistors and capacitors, thereby realizing the noise reduction effect.

[0027] 4. The signal addition circuit of the embedded reinforced localization loudspeaker is provided with a resistor R6 with an appropriate resistance value at the forward input end, which can ensure that the output end is zero when there is no left / right-channel audio signal, thereby realizing zero drift.

[0028] 5. The application provides a kind of embedded reinforcement type localization loudspeaker, signal amplification circuit uses integrated chip EG8401 to realize, and the channel input pin IN of chip EG8401 has adjustable resistance in series, when audio signal power is too large, the quality of output audio signal can be adjusted by adjusting the size of adjustable resistance, namely the application has the advantages of internal adjustable resistance adjusting voice noise.

[0029] 6. The application provides a kind of embedded reinforcement type localization loudspeaker, power filter circuit is used to filter the power supply voltage of the power supply output of signal addition integrated circuit and signal amplification integrated circuit, can the high frequency signal of audio signal, high frequency caused by lightning and other external equipment environment caused high frequency signal is filtered by low pass filter circuit to ground, to effectively filter out the interference of high frequency signal to audio signal.

[0030] 7. The application provides a kind of embedded reinforcement type localization loudspeaker, the power supply voltage of signal amplification circuit is stabilized by power supply voltage stabilizing circuit, can prevent the low voltage or high voltage of instantaneous low voltage or high voltage.

[0031] 8. The application provides a kind of embedded reinforcement type localization loudspeaker, audio anti-common mode interference circuit, low pass filter circuit, impedance matching circuit, signal addition circuit, signal amplification circuit, loudspeaker output circuit are all domestic type products, can realize 100% localization on the basis of guaranteeing the function performance of loudspeaker circuit. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The principle block diagram of a kind of embedded reinforcement type localization loudspeaker provided by the application is shown in the figure;

[0033] Figure 2 The circuit principle diagram of a kind of embedded reinforcement type localization loudspeaker provided by the application is shown in the figure;

[0034] 1-impedance matching circuit, 2-low pass filter circuit, 3-signal addition circuit, 4-power filter circuit I, 5-audio anti-common mode interference circuit, 6-signal amplification circuit, 7-power filter circuit II, 8-loudspeaker output circuit, 9-power supply voltage stabilizing circuit. DETAILED DESCRIPTION

[0035] In order to make the person in the art better understand the scheme of the present application, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0036] As Figure 1As shown, a kind of embedded reinforcement type localization loudspeaker, including audio anti-common mode interference circuit, impedance matching circuit, low pass filter circuit, signal addition circuit, signal amplification circuit, loudspeaker output circuit, power filter circuit I, power filter circuit II, power supply voltage stabilizing circuit;

[0037] The audio anti-common mode interference circuit is used to filter out common mode interference in left channel audio signal and right channel audio signal;The impedance matching circuit is used to prevent reflection of audio signal after filtering out common mode interference, and filter the superposition of audio signal, realize the noise reduction of audio signal;The low pass filter circuit is used to filter out high frequency interference signal in the audio signal after noise reduction;The signal addition circuit is used to mix the audio signals of two channels after filtering out high frequency interference signals;The signal amplification circuit is used to amplify the mixed audio signal;The loudspeaker output circuit is used to output the amplified audio signal;At the same time, power filter circuit I is used to filter the power supply voltage output by the power supply of signal addition circuit, power filter circuit II is used to filter the power supply voltage output by the power supply of signal amplification circuit, and power supply voltage stabilizing circuit is used to stabilize the power supply voltage of signal amplification circuit, prevent the instantaneous low voltage or high voltage of unstable power supply.

[0038] The circuit principle of embedded reinforcement type localization loudspeaker will be introduced in detail as follows, Figure 2 As shown, the audio anti-common mode interference circuit 5 includes left channel audio transformer U1 and right channel audio transformer U2, wherein, audio transformer is all used domestic chip with model MX671R, the primary coil of left channel audio transformer U1 is respectively used as left channel input end IN-L+ and analog ground AGND, the secondary coil is respectively used as left channel output end INL+ and signal ground GND, and left channel input end IN-L+ is connected with original left channel audio signal, left channel output end INL+ outputs left channel audio signal after filtering out common mode interference;The primary coil of right channel audio transformer U2 is respectively used as right channel input end IN-R+ and analog ground AGND, the secondary coil is respectively used as right channel output end INR+ and signal ground GND, and right channel input end IN-R+ is connected with original right channel audio signal, right channel output end INR+ outputs right channel audio signal after filtering out common mode interference.

[0039] It can be seen that the audio common-mode interference prevention circuit is provided with analog ground, left channel and right channel input and signal ground, left channel and right channel output to realize audio common-mode interference prevention, the signal ground is separated from the analog ground, namely AGND and GND are not interconnected in the PCB, interference is prevented, and the DC power frequency interference signal is prevented from being mixed into the circuit, the design circuit is particularly obvious in effect when the ship power is unstable, and the ship power voltage common-mode interference is effectively filtered out. Meanwhile, the peripheral device required by the audio common-mode interference prevention circuit is a console ruggedized computer, connection is performed in the console ruggedized computer, and the AGND and GND grounds are processed in the console ruggedized computer.

[0040] It should be noted that when the left channel and right channel audio signals are input at the same time through the console ruggedized computer, the audio transformers U1 and U2 effectively realize isolation, the DC power frequency interference signal is prevented from being mixed into the circuit, the effect is particularly obvious especially when the ship power is unstable, and the audio common-mode interference prevention circuit can effectively filter out the ship power voltage common-mode interference.

[0041] The impedance matching circuit 1 comprises resistors R10 and R11, wherein the right channel audio signal after common-mode interference filtering is input into the low-pass filter circuit through the series resistor R10, and the left channel audio signal after common-mode interference filtering is input into the low-pass filter circuit through the series resistor R11.

[0042] It should be noted that the impedance matching circuit realizes transmission line impedance matching on the audio signal transmission line, the circuit can effectively prevent the audio small signal transmission line signal reflection problem, filter out the superposition of signals, and realize noise reduction; that is, the audio signal filtered by the audio common-mode interference prevention circuit is connected with the low resistance resistors R10 and R11 in series on the transmission line, impedance matching is realized, the reflection of the audio signal is prevented, the superposition of signals is filtered out, and noise reduction is realized.

[0043] The low-pass filter circuit 2 comprises resistors R1-R4 and capacitors C1-C2, wherein one end of the resistor R1 is connected to the right channel audio signal after noise reduction output by the resistor R10, the other end is connected with the signal addition circuit in series with the resistor R3, and is also grounded through the capacitor C1; one end of the resistor R2 is connected to the left channel audio signal after noise reduction output by the resistor R11, the other end is connected with the signal addition circuit in series with the resistor R4, and is also grounded through the capacitor C2.

[0044] It should be noted that the low-pass filter circuit selects appropriate parameter resistors and capacitors on the basis of effective calculation, so that high frequency signals other than the set high frequency signals can be effectively filtered out, and noise reduction effect is realized; that is, the high frequency signals attached to the console ruggedized computer input audio signal, the high frequency signals caused by lightning strike and other external device environment can be filtered out to the ground through the low-pass filter circuit, and high frequency signal interference is effectively filtered out.

[0045] The signal adding circuit 3 comprises a domestic chip U4 (model GS8592), resistors R5-R6 and a capacitor C3, wherein the chip U4 is composed of two identical operational amplifiers, the two operational amplifiers are respectively used as a first channel and a second channel, the right channel audio signal filtered from high-frequency interference signals output by the resistor R3 and the left channel audio signal filtered from high-frequency interference signals output by the resistor R4 are connected to the reverse input end of the first channel, the forward input end of the first channel is connected with the resistor R6 of KΩ level in series, the output end of the first channel is connected with the mixed audio signal IN-OUT to the signal amplifying circuit, and the capacitor C3 and the resistor R5 are connected in parallel and then connected in series between the reverse input end and the output end of the first channel.

[0046] Therefore, the left / right channel audio signals pass through the audio anti-common mode interference circuit, the impedance matching circuit and the low-pass filter circuit to enter the signal adding circuit to realize the mixing of the left / right channel audio signals; meanwhile, it should be noted that the signal adding circuit is connected with the resistor R6 of KΩ level at the forward input end to ensure that the output end is zero when there is no left / right channel audio signal, to realize zero drift, that is, when there is no input audio signal, there is also no audio signal output, so that the output end is clamped at the "zero" point; the resistor and the capacitor are connected in parallel at the output end to reduce the high-frequency signal gain, effectively prevent the mixing of high-frequency signals into the amplified audio signals after the mixing of the audio signals, and realize noise reduction.

[0047] The signal amplifying circuit 6 comprises a chip U3, resistors R7-R8 and capacitors C7-C9, wherein the mixed audio signal IN-OUT is connected to the channel input pin IN of the chip U3 through the resistor R8 and the capacitor C9 connected in series, meanwhile, the chip U3 is connected with the resistor R7 and the capacitor C8 connected in parallel at the anti-distortion pin NCN, the resistor R7 and the capacitor C8 connected in parallel are grounded, the capacitor C7 connected to the internal reference source pin BYPASS of the chip U3 is grounded, the power supply pin VDD of the chip U3 is connected with the power supply voltage output by the power supply, and the channel reverse phase output pin VON and the channel same phase output pin VOP of the chip U3 output the amplified audio signals.

[0048] It should be noted that the signal amplification circuit is used to realize the amplification of the audio signal, the selected domestic integrated chip EG8401 has an anti-distortion function, and is provided with an excellent full-bandwidth EMI suppression internal circuit, a high signal-to-noise ratio, and an overcurrent and overheat protection circuit; the integrated circuit "NCN" pin matching resistor R7 and capacitor C8 make it work in the best mode of anti-distortion, and in the best mode, the anti-distortion function can adapt to the increase and decrease of the input signal amplitude or the power supply voltage, automatically adjust the loop gain by detecting the output signal amplitude, achieve the best effect of anti-distortion, greatly improve the sound quality effect, and maximize the output power; the integrated circuit "IN" pin is connected in series with the adjustable resistor R8, and when the external audio signal power is too large, the adjustable resistor R8 can be adjusted to adjust the output audio quality, and the effect of adjusting the sound quality is achieved.

[0049] The speaker output circuit 8 comprises a socket CN2, two channels of the socket CN2 respectively receive the amplified audio signals output by the channel anti-phase output pin VON and the channel in-phase output pin VOP, and output the amplified audio signals to the designated speaker.

[0050] The power filter circuit I 4 comprises a capacitor C4, wherein one end of the capacitor C4 is connected to the power supply voltage output by the power supply of the chip U4, and the other end is grounded.

[0051] The power filter circuit II 7 comprises a capacitor C6, wherein one end of the capacitor C6 is connected to the power supply voltage output by the power supply of the chip U3, and the other end is grounded.

[0052] The power stabilizing circuit 9 is composed of a capacitor C5, one end of which is grounded, and the other end is connected to the power supply pin VDD of the chip U3.

[0053] It should be noted that the signal amplification circuit chip of the present application is the control core, and the chip with the model EG8401 is used; the signal addition circuit chip uses a domestic chip with the model GS8592; the audio transformer chip of the audio anti-common mode interference circuit uses a domestic chip with the model MX671R; the speaker is a specific speaker, which is also a domestic model product; the resistors and capacitors required by other circuits also use domestic large factory military grade model products; that is, the audio anti-common mode interference circuit, the low-pass filter circuit, the impedance matching circuit, the signal addition circuit, the signal amplification circuit, the speaker output circuit, the power filter circuit I, the power filter circuit II and the power stabilizing circuit of the present application use chips, speakers, resistors and capacitors, which are all domestic model products, and can realize 100% domesticization on the basis of ensuring the function and performance of the speaker circuit.

[0054] In summary, the application makes the console reinforced computer output audio signals through the USB serial port, the output audio signals are filtered, noise-reduced and processed through the audio common-mode interference prevention circuit, the low-pass filter circuit and the impedance matching circuit to enter the signal addition circuit, the left / right channel audio signals are added through the signal addition circuit to output mixed audio signals, the mixed audio signals are adjusted in tone and power amplified through the signal amplification circuit to output amplified audio signals, and the amplified audio signals are output to the special loudspeaker to realize the video output required by the user.

[0055] Of course, the present application can have other various embodiments, and those skilled in the art can certainly make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application, but these corresponding changes and modifications shall all belong to the protection scope of the claims attached to the present application.

Claims

1. A recessed, ruggedized, and nationalized loudspeaker, characterized by, The audio anti-common-mode interference circuit, the impedance matching circuit, the low-pass filter circuit, the signal addition circuit, the signal amplification circuit and the loudspeaker output circuit are arranged in sequence. The audio anti-common-mode interference circuit is used for filtering common-mode interference in left and right audio signals; the impedance matching circuit is used for preventing reflection of the audio signals after filtering the common-mode interference and filtering superposition of the audio signals, so as to realize noise reduction of the audio signals; the low-pass filter circuit is used for filtering high-frequency interference signals in the audio signals after noise reduction; the signal addition circuit is used for mixing the audio signals of two channels after filtering the high-frequency interference signals; and the signal amplification circuit is used for amplifying the mixed audio signals. The loudspeaker output circuit is used for outputting the amplified audio signals. The audio anti-common-mode interference circuit includes a left-channel audio transformer U1 and a right-channel audio transformer U2, wherein two ends of a primary coil of the left-channel audio transformer U1 are respectively used as a left-channel input end IN-L+ and an analog ground AGND, two ends of a secondary coil are respectively used as a left-channel output end INL+ and a signal ground GND, the left-channel input end IN-L+ is connected to an original left-channel audio signal, and the left-channel output end INL+ outputs a left-channel audio signal after filtering common-mode interference; two ends of a primary coil of the right-channel audio transformer U2 are respectively used as a right-channel input end IN-R+ and the analog ground AGND, two ends of a secondary coil are respectively used as a right-channel output end INR+ and the signal ground GND, the right-channel input end IN-R+ is connected to an original right-channel audio signal, and the right-channel output end INR+ outputs a right-channel audio signal after filtering common-mode interference. The audio anti-common-mode interference circuit is provided with an analog ground, a left-channel input end, a right-channel input end, a signal ground, a left-channel output end and a right-channel output end, wherein the signal ground and the analog ground are separately arranged and are not interconnected in a PCB.

2. A built-in ruggedized local speaker as claimed in claim 1, characterized in that, The signal addition circuit is implemented by using a GS8592 chip, a KΩ resistor is connected in series with a positive input end of a first channel in the GS8592 chip, and a resistor and a capacitor which are connected in parallel with each other are connected to an output end.

3. A built-in ruggedized local speaker as claimed in claim 1, wherein, The signal amplification circuit is implemented by using an integrated chip EG8401, a resistor and a capacitor which are connected in parallel with each other are connected to an anti-distortion pin NCN of the integrated chip EG8401, and an adjustable resistor is connected in series with a channel input pin IN, so that when the power of the audio signal is too large, the quality of the output audio signal is adjusted by adjusting the size of the adjustable resistor.

4. The embedded reinforced domestic loudspeaker of any one of claims 1-3, wherein The impedance matching circuit includes a resistor R10 and a resistor R11, wherein the right-channel audio signal after filtering common-mode interference is input into the low-pass filter circuit through the resistor R10 in series, and the left-channel audio signal after filtering common-mode interference is input into the low-pass filter circuit through the resistor R11 in series. The low-pass filter circuit comprises resistors R1-R4 and capacitors C1-C2, wherein one end of the resistor R1 is connected to the right channel audio signal after noise reduction output by the resistor R10, the other end is connected to the signal addition circuit through the resistor R3 in series, and the resistor R3 is grounded through the capacitor C1; one end of the resistor R2 is connected to the left channel audio signal after noise reduction output by the resistor R11, the other end is connected to the signal addition circuit through the resistor R4 in series, and the resistor R4 is grounded through the capacitor C2; The signal addition circuit comprises a chip U4, resistors R5-R6 and a capacitor C3, wherein the chip U4 is composed of two same operational amplifiers, the two operational amplifiers are respectively used as a first channel and a second channel, the right channel audio signal filtered from high-frequency interference signal output by the resistor R3 and the left channel audio signal filtered from high-frequency interference signal output by the resistor R4 are connected to the reverse input end of the first channel, the forward input end of the first channel is connected to the resistor R6 in series, the mixed audio signal IN-OUT is connected to the signal amplification circuit, and the capacitor C3 and the resistor R5 are connected in parallel, and the capacitor C3 and the resistor R5 are connected between the reverse input end and the output end of the first channel in series. The signal amplification circuit comprises a chip U3, resistors R7-R8 and capacitors C7-C9, wherein the mixed audio signal IN-OUT is connected to the channel input pin IN of the chip U3 through the resistor R8 and the capacitor C9 in series, the resistor R7 and the capacitor C8 are connected in parallel and connected to the chip U3 through the resistor R7 and the capacitor C8, the resistor R7 and the capacitor C8 are grounded, the capacitor C7 is connected to the internal reference source pin BYPASS of the chip U3 and grounded, the power supply pin VDD of the chip U3 is connected to the power supply voltage output by the power supply, and the channel inverse output pin VON and the channel same phase output pin VOP of the chip U3 output the amplified audio signal. The speaker output circuit comprises a socket CN2, the two channels of the socket CN2 receive the amplified audio signal output by the channel inverse output pin VON and the channel same phase output pin VOP, and output the amplified audio signal to the designated speaker.

5. A fit-in type reinforced localised speaker as claimed in claim 4, wherein, Further comprising a power filter circuit I and a power filter circuit II; The power filter circuit I is used for filtering the power supply voltage output by the power supply of the signal addition circuit, and the power filter circuit II is used for filtering the power supply voltage output by the power supply of the signal amplification circuit.

6. A bezel-reinforced, locally manufactured loudspeaker according to claim 5, characterized in that The power filter circuit I comprises a capacitor C4, wherein one end of the capacitor C4 is connected to the power supply voltage output by the power supply of the chip U4, and the other end is grounded. The power filter circuit II comprises a capacitor C6, wherein one end of the capacitor C6 is connected to the power supply voltage output by the power supply of the chip U3, and the other end is grounded.

7. A built-in ruggedized local speaker as claimed in claim 4, wherein, Further comprising a power stabilizing circuit for stabilizing the power supply voltage of the signal amplification circuit, and the power stabilizing circuit is composed of a capacitor C5, one end of the capacitor C5 is grounded, and the other end is connected to the power supply pin VDD of the chip U3.

8. A built-in type reinforced domestic loudspeaker as claimed in any one of claims 1 to 3, 5 to 7, characterized in that, The signal amplification circuit is realized by using a domestic chip of EG8401; the signal addition circuit is realized by using a domestic chip of GS8592; the audio anti-common-mode interference circuit is realized by using a domestic chip of MX671R; the loudspeaker is also a domestic product; and the resistors and capacitors required by other circuits are also selected from domestic military-grade products.

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