Guqin table sound amplification system and Guqin table

Abstract

The invention relates to a seven-stringed plucked instrument desk sound amplification system and a seven-stringed plucked instrument desk, the sound amplification system comprises a microphone pickup circuit, a balance conversion circuit, a pre-amplification circuit, a post-stage power amplification circuit and a circuit structure with a small magnification step-by-step amplification, after a microphone collects an electric signal, filtering and noise reduction are carried out, then first-stage small magnification amplification is carried out, the amplification rate is 10 times, and the first-stage small magnification amplification is carried out; it is ensured that low level is not lost, high level is not overflowed, and effective collection of the whole range is ensured. After the signal is buffered, the signal is amplified at a small magnification of 10 times, so that a certain thrust is applied to the rear stage under the condition of ensuring the integrity of the signal. The amplification factor of 4.7 multiplying power is adopted in the last stage of amplification, so that the amplification factor of 470 times is adopted in the preceding stage in total, the output voltage amplitude can be effectively improved without distortion, and finally electro-acoustic conversion is carried out through the power amplifier circuit so as to achieve the purpose of ancient sound amplification. According to the invention, the audio frequency is expanded, frame loss or sonic boom of the audio frequency is avoided, and teaching training and large-scale playing are facilitated.

Description

Technical Field

[0001] This patent application belongs to the technical field of musical equipment, and more specifically, relates to a guqin table sound amplification system and a guqin table. Background Art

[0002] Guqin has a rich variety of playing techniques, which not only focus on the appreciation effect, but also reflect the skill level of the performer. The performance characteristics of Guqin include strong solo performance, elegant timbre, unique techniques and emphasis on expressing emotions. These characteristics make Guqin a unique instrument with high artistic and cultural value.

[0003] Due to the shape of the guqin, its resonance cavity is small and limited. The sound produced by playing on a traditional guqin table is relatively low, making it suitable for solo performances but not very suitable for large-scale performances. It is also not conducive to large-scale teaching demonstrations and has significant limitations.

[0004] Moreover, according to the analysis of the guqin's frequency spectrum distribution, it was found that the guqin's audio range continuously progresses from 50Hz to more than 20KHz, and its sound range is very wide. At the same time, due to the very flexible playing techniques, there are outlines of frequency gradients and sudden transitions, which requires the sound amplification circuit to have sufficient bandwidth and a very high conversion rate to avoid frame loss or popping sounds.

[0005] Therefore, in order to promote the guqin culture and allow the sound of the guqin to be heard in a larger space, it is necessary to develop a guqin table sound amplification system based on the traditional guqin table. The guqin table equipped with the above-mentioned sound amplification system can not only amplify the audio, but also avoid audio frame loss or popping, which is convenient for teaching and training and large-scale performances. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a guqin table sound amplification system and a guqin table, which can amplify the audio, avoid audio frame loss or popping, and ensure effective collection of the full range of sounds.

[0007] In order to solve the above problems, the technical solution adopted by the present invention is:

[0008] A guqin table sound amplification system is provided with a sound amplification circuit, which is a circuit structure of small-multiplier step-by-step amplification, including a microphone pickup circuit, a balanced conversion circuit, a preamplifier circuit, and a post-stage power amplifier circuit connected in sequence.

[0009] The microphone pickup circuit completes the sound-to-electric conversion of the guqin sound, converting the guqin sound into an electrical signal while filtering out the low-frequency noise transmitted through the guqin.

[0010] The balanced conversion circuit converts the single-channel electrical signal generated by the microphone pickup circuit into a symmetrical balanced differential-mode electrical signal to eliminate common-mode interference and lay the foundation for providing low-noise signal gain for the subsequent preamplifier circuit;

[0011] The preamplifier circuit is used to amplify the differential signal output by the balanced conversion circuit;

[0012] The post-amplifier circuit is used to further amplify the electrical signal input by the pre-amplifier circuit, and then drive the speaker (speaker output unit) to complete the electrical-to-acoustic conversion, thereby playing a role in sound amplification.

[0013] In addition, the present invention also proposes a guqin table, which utilizes the circuit in the sound amplification system mentioned in the present invention.

[0014] Due to the adoption of the above technical solution, the beneficial effects achieved by the present invention are:

[0015] The invention is formed by modifying the traditional guqin table and adding a sound amplification circuit, which is composed of four parts: a microphone pickup circuit, a balanced conversion circuit, a preamplifier circuit and a post-stage power amplifier circuit.

[0016] The microphone pickup circuit completes the sound-to-electric conversion of the guqin's sound, converting the guqin's sound into an electrical signal, while filtering out the low-frequency noise transmitted through the guqin.

[0017] The balanced conversion circuit converts the single-channel electrical signal generated by the microphone pickup circuit into a symmetrical balanced differential-mode electrical signal to eliminate common-mode interference and lay the foundation for providing low-noise signal gain for subsequent amplification.

[0018] The function of the preamplifier circuit is to amplify the differential signal output by the balanced conversion circuit. As we all know, since the electrical signal output by the microphone is very weak, it cannot directly drive the subsequent power amplifier circuit. It is necessary to amplify the weak signal first to increase the output power and drive level to achieve the input level required by the power amplifier.

[0019] The function of the post-stage power amplifier circuit is to further amplify the electrical signal input by the pre-amplifier circuit, and then drive the speaker output unit to complete the electro-acoustic conversion, thereby amplifying the sound so that the sound of the guqin can be heard in a larger space.

[0020] The present invention adopts a circuit structure of small-rate step-by-step amplification. After the microphone collects the electrical signal, it is filtered and noise-reduced, and then the first stage of small-rate amplification is performed, with an amplification rate of about 10 times, to ensure that the low level is not lost and the high level does not overflow, thereby ensuring the effective collection of the full range. After the signal is buffered, a small-rate amplification of 10 times is performed again to ensure that there is a certain thrust on the subsequent stage under the condition of signal integrity. The last stage of amplification adopts an amplification factor of 4.7 times. In this way, the front stage has a total amplification factor of 470 times, which can effectively increase the output voltage amplitude without distortion. Finally, the power amplifier circuit is used to perform electro-acoustic conversion to achieve the purpose of ancient sound amplification. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a system block diagram of the present invention.

[0022] Figure 2 It is a circuit diagram of the left channel in the microphone pickup circuit of the present invention.

[0023] Figure 3 It is a circuit diagram of the right channel in the microphone pickup circuit of the present invention.

[0024] Figure 4 The circuit for the left channel in the preamplifier circuit of the present invention Figure 1 .

[0025] Figure 5 The circuit for the right channel in the preamplifier circuit of the present invention Figure 1 .

[0026] Figure 6 The circuit for the left channel in the preamplifier circuit of the present invention Figure 2 .

[0027] Figure 7 The circuit for the right channel in the preamplifier circuit of the present invention Figure 2 .

[0028] Figure 8 It is a circuit diagram of the rear-stage power amplifier circuit of the present invention. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below with reference to the embodiments.

[0030] A guqin table sound amplification system, such as Figure 1 , a sound amplification circuit is provided, which is characterized in that the sound amplification circuit is a circuit structure of small-rate step-by-step amplification, including a microphone pickup circuit, a balanced conversion circuit, a preamplifier circuit, and a post-stage power amplifier circuit connected in sequence.

[0031] The microphone pickup circuit completes the sound-to-electric conversion of the guqin sound, converting the guqin sound into an electrical signal while filtering out the low-frequency noise transmitted through the guqin.

[0032] The balanced conversion circuit converts the single-channel electrical signal generated by the microphone pickup circuit into a symmetrical balanced differential-mode electrical signal to eliminate common-mode interference and lay the foundation for providing low-noise signal gain for the subsequent preamplifier circuit;

[0033] The preamplifier circuit is used to amplify the differential signal output by the balanced conversion circuit;

[0034] The post-amplifier circuit is used to further amplify the electrical signal input by the pre-amplifier circuit, and then drive the speaker (speaker output unit) to complete the electrical-to-acoustic conversion, thereby playing a role in sound amplification.

[0035] The specific circuit is:

[0036] The microphone pickup circuit, balanced conversion circuit, preamplifier circuit, and post-amplifier circuit all include left and right channels. The circuit connection relationship of each left and right channel is the same. Take the left channel as an example. Figure 2 As shown, the left channel includes a capacitor C24, one end of the capacitor C24 is connected to the microphone signal MIC L+, and the other end is connected to the G pole of the transistor Q1A, the D pole of the transistor Q1A is respectively connected to the resistor R26 and the capacitor C21, the other end of the capacitor C21 is connected to the resistor R27, and the other end of the resistor R27 is output as the LINE_L+ signal;

[0037] The other end of the resistor R26 is connected to the polar capacitor C54, the resistor R50, and the resistor R39. The other end of the resistor R50 is connected to the polar capacitor C57 and the resistor R23. The other end of the polar capacitor C54 and the other end of the polar capacitor C57 are both connected to M_GND, where M_GND is a ground signal after GND is filtered. The other end of the resistor R23 is connected to VCC_12V+.

[0038] The S-pole of transistor Q1A is connected to resistor R36 and capacitor C71 respectively, the other end of resistor R36 is connected in parallel with polar capacitor C31, and the other end of resistor R36 is connected to M_GND; the other end of capacitor C71 is connected to resistor R51, and the other end of resistor R51 is used as LINE_L- signal output on one hand, and connected to M_GND through capacitor C86 on the other hand;

[0039] The microphone signal MIC L- is connected to the resistor R21 through the switch JP2, the other end of the resistor R21 is connected to the capacitor C41 and the polarity capacitor C42, and the other end of the polarity capacitor C42 is connected to M_GND; the other end of the capacitor C41 is connected to the resistor R39, and the other end of the capacitor C41 is connected to the emitter of the transistor Q2 through the resistor R22 and the resistor R31 in sequence, and the resistor R22 and the resistor R31 are connected to M_GND through the diode DIC;

[0040] The collector of transistor Q2 is connected to the phantom power supply VCC_48V, and the base of transistor Q2 is connected to resistor R48 and capacitor C45 respectively. The other end of resistor R48 is connected to GND through capacitor C48 on the one hand, and is also connected to the phantom power supply VCC_48V through resistor R49 on the other hand; the base of transistor Q2 is also connected to its emitter through resistor R41.

[0041] exist Figure 2 In the embodiment, two ends of the resistor R22 are respectively connected to a polar capacitor C126 and a polar capacitor C43, and the other end of the polar capacitor C126 and the other end of the polar capacitor C43 are both connected to M_GND;

[0042] The other end of the capacitor C41 is also connected to a resistor R35, the other end of the resistor R35 is connected to a resistor R45, the other end of the resistor R45 is connected to M_GND through the capacitor C1 on one hand, and connected to the microphone signal MIC L+ on the other hand;

[0043] A resistor R24 ​​is connected between the resistor R21 and the polar capacitor C42. The resistor R24 ​​is connected in parallel with the capacitor C19. The other end of the capacitor C19 is connected to M_GND via the capacitor C28, the resistor R38, and the resistor R40 in sequence. The other end of the capacitor C19 is also connected to the microphone signal MICL-, and the microphone signal MIC L- is also connected to M_GND via the resistor R30.

[0044] A capacitor C2 is also connected between the LINE_L- signal and the LINE_L+ signal.

[0045] Figure 3 This is the right channel of the microphone pickup circuit and will not be described in detail.

[0046] like Figure 4-Figure 7 The preamplifier circuit includes an RC filter circuit connected to both the LINE_L- signal and the LINE_L+ signal, a buffer inverter circuit connected to the RC filter circuit, and a voltage amplifier circuit connected to the buffer inverter circuit. The "X10" in the figure means 10 times amplification.

[0047] by Figure 4 Taking the left channel in as an example, the RC filter circuit includes a resistor R102, a resistor R109, a capacitor C105, a capacitor C109, and a capacitor C125. The LINE_L+ signal is connected to M_GND through the resistor R102 and the capacitor C105, and the LINE_L- signal is connected to the capacitor C109 through the resistor R109. The other end of the capacitor C109 is also connected to the other end of the resistor R102. The capacitor C125 is connected to the capacitor C131 and the capacitor C109 respectively, and the other end of the capacitor C125 is connected to M_GND.

[0048] The buffer inverting circuit includes an operator U100B and an operator U101A. Pin 5 of the operator U100B is connected to the LINE_L+ signal through a resistor R102, and pin 6 is connected to a resistor R108. The other end of the resistor R108 is respectively connected to pin 7 of the operator U100B, a capacitor C102, and a resistor R110. The other end of the resistor R110 is respectively connected to a resistor R117, a resistor R115, a capacitor C127, and pin 1 of the operator U101A; the resistor R11 7 The other end is connected to M_GND through capacitor C131 and connected to pin 3 of operator U101A. Pin 8 of operator U101A is connected to VCC_12V+ and connected in parallel with M_GND via capacitor C119 and capacitor C120. Pin 4 of operator U101A is connected to VCC_12V- and connected in parallel with M_GND via capacitor C134 and capacitor C139. The other end of resistor R115 is also connected to pin 2 of operator U101A.

[0049] The voltage amplifier circuit includes an op amp U100A and an op amp U101B. The other end of the capacitor C102 is connected to the 2nd pin of the op amp U100A through resistors R105 and R106. The 1st pin of the op amp U100A outputs the MIC_L_OUT_P signal through capacitor C108. The 3rd pin of the op amp U100A is connected to resistor R111, capacitor C118, and the 5th pin of the op amp U101B. The other end of the resistor R111 and the other end of the capacitor C118 are both connected to M_GND.

[0050] The other end of capacitor C127 is connected to pin 6 of op amp U101B through resistors R118 and R121. M_GND at resistor R111 is also connected to resistor R106 through resistor R112 and resistor R121 through resistor R116. Capacitor C133 and resistor R123 are connected in parallel between pins 6 and 7 of op amp U101B. Pin 7 of op amp U101B outputs MIC_L_OUT_N signal through capacitor C126. The two signals MIC_L_OUT_N and MIC_L_OUT_P, the signal starting with MIC is the final output signal of the microphone pickup circuit, and the output signal of MIC is the input signal of the preamplifier circuit.

[0051] at the same time, Figure 4 The middle of the capacitor C116 is also provided, and both ends of the capacitor C116 are connected to the resistor R106 and the resistor R121.

[0052] exist Figure 6In the figure, the MIC_L_OUT_P signal is connected to the 2nd pin of the operator U200A through the resistor R201, the resistor R200 and the capacitor C200 are connected in parallel between the 2nd pin and the 1st pin of the operator U200A, the 1st pin of the operator U200A is connected to the 3rd pin of the operator U201A through the capacitor C202 and the resistor R205, the 1st pin of the operator U201A is connected to the 5th pin of the operator U200B through the capacitor C214, and the 7th pin of the operator U200B outputs the PREAMP_OUT_L signal; correspondingly, Figure 7 In the example, the right channel output has PREAMP_OUT_R signal.

[0053] Continue to refer Figure 6 , the MIC_L_OUT_N signal is connected to the 6th pin of the operator U201B through the resistor R213, and the resistor R214 and the capacitor C223 are connected in parallel between the 6th pin and the 7th pin of the operator U201B, and the 7th pin of the operator U201B is connected to the 2nd pin of the operator U201A through the capacitor C222 and the resistor R211 in turn, and the resistor R212 and the capacitor C218 are connected in parallel between the 1st pin and the 2nd pin of the operator U201A, and the 8th pin of the operator U201A is connected to VCC_12V+, and the capacitor C220 and the capacitor C221 are connected in parallel between the 8th pin of the operator U201A and M_GND; the 4th pin of the operator U201A is connected to VCC_12V-, and the capacitor C207 and the capacitor C204 are connected in parallel between the 4th pin of the operator U201A and M_GND.

[0054] It also includes capacitor C215, resistor R204, and resistor R208. Capacitor C215 is connected between capacitor C202 and capacitor C222. Resistor R204 and resistor R208 are connected in series and also connected in parallel between capacitor C202 and capacitor C222. Both ends of capacitor C215 are connected to M_GND through capacitor C206 and capacitor C219 respectively.

[0055] The MIC_L_OUT_P signal is also connected to the resistor R207, and the MIC_L_OUT_N signal is also connected to the resistor R210. The other end of the resistor R207 and the other end of the resistor R210 are both connected to M_GND; the other end of the resistor R207 is respectively connected to the 3rd pin of the operator U200A and the 5th pin of the operator U201B through the capacitor C213;

[0056] A capacitor C212 is connected between the MIC_L_OUT_P signal and the MIC_L_OUT_N signal, and both ends of the capacitor C212 are connected to M_GND via capacitors C203 and C217, respectively.

[0057] Combination Figure 8From the above, the preamplifier circuit of the present invention also outputs Bluetooth signals, namely BLE_OUT_R for the right channel and BLE_OUT_L for the left channel, and both BLE_OUT_R and BLE_OUT_L are connected to the post-stage power amplifier circuit.

[0058] exist Figure 8 In the figure, the post-stage power amplifier circuit includes capacitor C3, capacitor C6, capacitor C8, and capacitor C11. One end of capacitor C3 is connected to the input signal PREAMP_OUT_L through adjustable potentiometer R4A, and the other end is connected to pin 8 of power amplifier IC1 through resistor R8. One end of capacitor C6 is connected to the input signal BLE_OUT_L through adjustable potentiometer R10A, and the other end is connected to pin 8 of power amplifier IC1 through resistor R21. One end of capacitor C8 is connected to the input signal BLE_OUT_R through adjustable potentiometer R10B, and the other end is connected to pin 13 of power amplifier IC1 through resistor R22. One end of capacitor C11 is connected to the input signal PREAMP_OUT_R through adjustable potentiometer R4B, and the other end is connected to pin 13 of power amplifier IC1 through resistor R11. Pins 13 and 8 of power amplifier IC1 are also connected to GND through resistors R12 and R7, respectively. Figure 8 It can be seen that the four signals PREAMP_OUT_R, BLE_OUT_R, BLE_OUT_L, and PREAMP_OUT_L are all output signals of the preamplifier circuit, and the input signal of the preamplifier circuit is the MIC signal.

[0059] Pin 6 of the power amplifier IC1 is connected to capacitor C7, VCC_12V-, and pin 11 of the power amplifier IC1, and pin 4 of the power amplifier IC1 is connected to VCC_12V- and polar capacitor C10. The other end of capacitor C7 and the other end of polar capacitor C10 are both connected to GND.

[0060] Pin 12 of the power amplifier IC1 is connected to resistors R16 and R17. The other end of resistor R17 is connected to GND through polarity capacitor C12. The other end of resistor R16 is connected to GND through resistor R18 and capacitor C13 in turn. At the same time, the other end of resistor R16 is also connected to pin 1 of the power amplifier IC1. Pin 1 of the power amplifier IC1 also outputs AMP_OUT_R signal to the speaker after passing through polarity capacitor C9 and resistor R13 in turn.

[0061] Pin 7 of power amplifier IC1 is connected to resistors R2 and R5. The other end of resistor R2 is connected to GND through polar capacitor C1. The other end of resistor R5 is connected to GND through resistor R3 and capacitor C2. At the same time, the other end of resistor R5 is also connected to pin 3 of power amplifier IC1. Pin 3 of power amplifier IC1 also outputs AMP_OUT_L signal to the speaker after passing through polar capacitor C5 and resistor R6. Circuit Figure 8In the example, the two signals AMP_OUT_R and AMP_OUT_L are directly output to the speaker.

[0062] See you next time Figure 8 , Pins 2 and 15 of the power amplifier IC1 are connected to VCC_12V+, VCC_12V+ is connected to GND through polarity capacitor C4, and Pins 5 and 10 of the power amplifier IC1 are connected to GND through resistor R15.

[0063] At the same time, the present invention also provides a guqin table, which utilizes the circuit in the above-mentioned guqin table sound amplification system to meet the sound amplification needs of the guqin table.

[0064] refer to Figure 2 , Figure 3 The microphone pickup circuit includes a left channel and a right channel. The circuit connection relationship of the left channel and the right channel is the same. Taking the left channel as an example, the microphone signal is coupled to the transistor Q1A through the capacitor C24, and is amplified by the transistor Q1A and output. The 48V phantom power is filtered by the transistor Q2 current limiter, and then provided with a polarization voltage for the microphone through the capacitor C41 to complete the pickup of external sound.

[0065] The balanced conversion circuit is not the core of this case. As long as it can complete the balanced conversion of the signal, the circuit diagram will not be provided here.

[0066] refer to Figure 4-Figure 7 In the preamplifier circuit, the signal output by the microphone pickup circuit passes through the RC filter circuit composed of resistor R102, resistor R109 and capacitor C105, as well as capacitors C125 and C109 to filter out circuit noise and then is sent to U100B for buffering. At the same time, the inverting circuit composed of U101A generates a balanced signal with a phase difference of 180 degrees from the input, which is sent to the operational amplifiers U100A and U101B for voltage amplification after passing through coupling capacitors C102 and C127.

[0067] refer to Figure 8 In the post-stage power amplifier circuit, after voltage amplification in the front stage, the output signal is used as the input signal of the driving power amplifier circuit, and is coupled to the power amplifier IC1 (power amplifier chip) through capacitors C3, C6, C8, and C11. The power amplifier IC1 amplifies the voltage and current of the input signal, and then isolates the DC component through capacitors C5 and C9 and couples it to the speaker, and finally plays the sound of the guqin through the speaker.

[0068] From the above content, it can be known that the present invention is a circuit structure of step-by-step amplification with a small magnification. After the microphone collects the electrical signal, it is filtered and noise-reduced, and then the first stage of small magnification amplification is performed, such as a magnification of 10 times, to ensure that the low level is not lost and the high level does not overflow, so as to ensure the effective collection of the full range. After the signal is buffered, a small magnification of about 10 times is performed to ensure that there is a certain thrust on the back stage under the condition of signal integrity. The last stage of amplification adopts an amplification factor of 4.7 times, so that the front stage has a total amplification of about 470 times, which can effectively increase the output voltage amplitude without distortion, and finally perform electro-acoustic conversion through the power amplifier circuit to achieve the purpose of ancient sound amplification. The present invention expands the audio, avoids frame loss or burst sound of the audio, is convenient for the teaching and training of the guqin and large-scale performances, and has a very high market promotion value.

Claims

1. A guqin table sound amplification system, provided with a sound amplification circuit, characterized in that: The sound amplification circuit is a circuit structure with a small-rate step-by-step amplification, including a microphone pickup circuit, a balanced conversion circuit, a preamplifier circuit, and a post-amplifier circuit connected in sequence. The microphone pickup circuit completes the sound-to-electric conversion of the guqin sound, converting the guqin sound into an electrical signal while filtering out the low-frequency noise transmitted through the guqin. The balanced conversion circuit converts the single-channel electrical signal generated by the microphone pickup circuit into a symmetrical balanced differential-mode electrical signal to eliminate common-mode interference and lay the foundation for providing low-noise signal gain for the subsequent preamplifier circuit; The preamplifier circuit is used to amplify the differential signal output by the balanced conversion circuit; The post-amplifier circuit is used to further amplify the electrical signal input by the pre-amplifier circuit, and finally drive the speaker to complete the electrical-to-acoustic conversion and play a role in sound amplification.

2. The guqin table sound amplification system according to claim 1, characterized in that: The microphone pickup circuit includes a left channel and a right channel. The circuit connection relationship of the left channel and the right channel is the same. The left channel includes a capacitor C24. One end of the capacitor C24 is connected to the microphone signal MIC L+, and the other end is connected to the G pole of the transistor Q1A. The D pole of the transistor Q1A is respectively connected to the resistor R26 and the capacitor C21. The other end of the capacitor C21 is connected to the resistor R27. The other end of the resistor R27 is used as the LINE_L+ signal output; The other end of the resistor R26 is connected to the polar capacitor C54, the resistor R50, and the resistor R39. The other end of the resistor R50 is connected to the polar capacitor C57 and the resistor R23. The other end of the polar capacitor C54 and the other end of the polar capacitor C57 are both connected to M_GND, where M_GND is a ground signal after GND is filtered. The other end of the resistor R23 is connected to VCC_12V+. The S-pole of transistor Q1A is connected to resistor R36 and capacitor C71 respectively, the other end of resistor R36 is connected in parallel with polar capacitor C31, and the other end of resistor R36 is connected to M_GND; the other end of capacitor C71 is connected to resistor R51, and the other end of resistor R51 is used as LINE_L- signal output on one hand, and connected to M_GND through capacitor C86 on the other hand; The microphone signal MIC L- is connected to the resistor R21 through the switch JP2, the other end of the resistor R21 is connected to the capacitor C41 and the polarity capacitor C42, and the other end of the polarity capacitor C42 is connected to M GND; the other end of the capacitor C41 is connected to the resistor R39, and the other end of the capacitor C41 is connected to the emitter of the transistor Q2 through the resistor R22 and the resistor R31 in sequence, and the resistor R22 and the resistor R31 are connected to M_GND through the diode DIC; The collector of transistor Q2 is connected to the phantom power supply VCC_48V, and the base of transistor Q2 is connected to resistor R48 and capacitor C45 respectively. The other end of resistor R48 is connected to GND through capacitor C48 on the one hand, and is also connected to the phantom power supply VCC_48V through resistor R49 on the other hand; the base of transistor Q2 is also connected to its emitter through resistor R41.

3. The guqin table sound amplification system according to claim 2, characterized in that: Two ends of the resistor R22 are respectively connected to a polar capacitor C126 and a polar capacitor C43, and the other end of the polar capacitor C126 and the other end of the polar capacitor C43 are both connected to M_GND; The other end of the capacitor C41 is also connected to a resistor R35, the other end of the resistor R35 is connected to a resistor R45, the other end of the resistor R45 is connected to M_GND through the capacitor C1 on one hand, and connected to the microphone signal MIC L+ on the other hand; A resistor R24 ​​is connected between the resistor R21 and the polar capacitor C42. The resistor R24 ​​is connected in parallel with the capacitor C19. The other end of the capacitor C19 is connected to M_GND via the capacitor C28, the resistor R38, and the resistor R40 in sequence. The other end of the capacitor C19 is also connected to the microphone signal MIC L-, and the microphone signal MIC L- is also connected to M_GND via the resistor R30. A capacitor C2 is also connected between the LINE_L- signal and the LINE_L+ signal.

4. The guqin table sound amplification system according to claim 3, characterized in that: The preamplifier circuit includes an RC filter circuit connected to both the LINE_L- signal and the LINE_L+ signal, a buffer inverting circuit connected to the RC filter circuit, and a voltage amplifier circuit connected to the buffer inverting circuit; The RC filter circuit includes a resistor R102, a resistor R109, a capacitor C105, a capacitor C109, and a capacitor C125. The LINE_L+ signal is connected to M_GND through the resistor R102 and the capacitor C105. The LINE_L- signal is connected to the capacitor C109 through the resistor R109. The other end of the capacitor C109 is also connected to the other end of the resistor R102. The capacitor C125 is connected to the capacitor C131 and the capacitor C109 respectively. The other end of the capacitor C125 is connected to M_GND. The buffer inverting circuit includes an operator U100B and an operator U101A. Pin 5 of the operator U100B is connected to the LINE_L+ signal through a resistor R102, and pin 6 is connected to a resistor R108. The other end of the resistor R108 is respectively connected to pin 7 of the operator U100B, a capacitor C102, and a resistor R110. The other end of the resistor R110 is respectively connected to a resistor R117, a resistor R115, a capacitor C127, and pin 1 of the operator U101A; the resistor R11 7 The other end is connected to M_GND through capacitor C131 and connected to pin 3 of operator U101A. Pin 8 of operator U101A is connected to VCC_12V+ and connected in parallel with M_GND via capacitor C119 and capacitor C120. Pin 4 of operator U101A is connected to VCC_12V- and connected in parallel with M_GND via capacitor C134 and capacitor C139. The other end of resistor R115 is also connected to pin 2 of operator U101A. The voltage amplifier circuit includes an op amp U100A and an op amp U101B. The other end of the capacitor C102 is connected to the 2nd pin of the op amp U100A through resistors R105 and R106. The 1st pin of the op amp U100A outputs the MIC_L_OUT_P signal through capacitor C108. The 3rd pin of the op amp U100A is connected to resistor R111, capacitor C118, and the 5th pin of the op amp U101B. The other end of the resistor R111 and the other end of the capacitor C118 are both connected to M_GND. The other end of capacitor C127 is connected to pin 6 of op amp U101B through resistors R118 and R121. M_GND at resistor R111 is also connected to resistor R106 through resistor R112 and resistor R121 through resistor R116. Capacitor C133 and resistor R123 are connected in parallel between pins 6 and 7 of op amp U101B. Pin 7 of op amp U101B outputs MIC_L_OUT_N signal through capacitor C126.

5. The guqin table sound amplification system according to claim 4, characterized in that: The device further includes a capacitor C116 , and both ends of the capacitor C116 are connected to the resistor R106 and the resistor R121 .

6. The guqin table sound amplification system according to claim 5, characterized in that: The MIC_L_OUT_P signal is connected to the pin 2 of the operator U200A via the resistor R201. The resistor R200 and the capacitor C200 are connected in parallel between the pin 2 and the pin 1 of the operator U200A. The pin 1 of the operator U200A is connected to the pin 3 of the operator U201A via the capacitor C202 and the resistor R205 in turn. The pin 1 of the operator U201A is connected to the pin 5 of the operator U200B via the capacitor C214. The pin 7 of the operator U200B outputs the PREAMP_OUT_L signal. Accordingly, the right channel outputs the PREAMP_OUT_R signal. The MIC_L_OUT_N signal is connected to the 6th pin of the operator U201B through the resistor R213, and the resistor R214 and the capacitor C223 are connected in parallel between the 6th pin and the 7th pin of the operator U201B, and the 7th pin of the operator U201B is connected to the 2nd pin of the operator U201A through the capacitor C222 and the resistor R211 in turn, and the resistor R212 and the capacitor C218 are connected in parallel between the 1st pin and the 2nd pin of the operator U201A, and the 8th pin of the operator U201A is connected to VCC_12V+, and the capacitor C220 and the capacitor C221 are connected in parallel between the 8th pin of the operator U201A and M_GND; the 4th pin of the operator U201A is connected to VCC_12V-, and the capacitor C207 and the capacitor C204 are connected in parallel between the 4th pin of the operator U201A and M_GND; It also includes a capacitor C215, a resistor R204, and a resistor R208. The capacitor C215 is connected between the capacitor C202 and the capacitor C222. The resistor R204 and the resistor R208 are connected in series and are also connected in parallel between the capacitor C202 and the capacitor C222. Both ends of the capacitor C215 are connected to M_GND through the capacitor C206 and the capacitor C219 respectively. The MIC_L_OUT_P signal is also connected to the resistor R207, and the MIC_L_OUT_N signal is also connected to the resistor R210. The other end of the resistor R207 and the other end of the resistor R210 are both connected to M_GND; the other end of the resistor R207 is respectively connected to the 3rd pin of the operator U200A and the 5th pin of the operator U201B through the capacitor C213; A capacitor C212 is connected between the MIC_L_OUT_P signal and the MIC_L_OUT_N signal, and both ends of the capacitor C212 are connected to M_GND via capacitors C203 and C217, respectively.

7. The guqin table sound amplification system according to claim 6, characterized in that: The preamplifier circuit also outputs Bluetooth signals, namely BLE_OUT_R for the right channel and BLE_OUT_L for the left channel. Both BLE_OUT_R and BLE_OUT_L are connected to the post-stage power amplifier circuit.

8. The guqin table sound amplification system according to claim 7, characterized in that: The post-stage power amplifier circuit includes capacitor C3, capacitor C6, capacitor C8, and capacitor C11. One end of capacitor C3 is connected to the input signal PREAMP_OUT_L through the adjustable potentiometer R4A, and the other end is connected to the 8th pin of the power amplifier IC1 through the resistor R8. One end of capacitor C6 is connected to the input signal BLE_OUT_L through the adjustable potentiometer R10A, and the other end is connected to the 8th pin of the power amplifier IC1 through the resistor R21; one end of capacitor C8 is connected to the input signal BLE_OUT_R through the adjustable potentiometer R10B, and the other end is connected to the 13th pin of the power amplifier IC1 through the resistor R22; one end of capacitor C11 is connected to the input signal PREAMP_OUT_R through the adjustable potentiometer R4B, and the other end is connected to the 13th pin of the power amplifier IC1 through the resistor R11. The 13th pin and the 8th pin of the power amplifier IC1 are also connected to GND through the resistor R12 and the resistor R7 respectively. Pin 6 of power amplifier IC1 is connected to capacitor C7, VCC_12V-, and pin 11 of power amplifier IC1. Pin 4 of power amplifier IC1 is connected to VCC_12V- and polar capacitor C10. The other end of capacitor C7 and the other end of polar capacitor C10 are both connected to GND. Pin 12 of the power amplifier IC1 is connected to resistors R16 and R17. The other end of resistor R17 is connected to GND via polar capacitor C12. The other end of resistor R16 is connected to GND via resistor R18 and capacitor C13. Meanwhile, the other end of resistor R16 is also connected to pin 1 of the power amplifier IC1. Pin 1 of the power amplifier IC1 also outputs AMP_OUT_R signal to the speaker via polar capacitor C9 and resistor R13. Pin 7 of the power amplifier IC1 is connected to resistors R2 and R5. The other end of resistor R2 is connected to GND through polar capacitor C1. The other end of resistor R5 is connected to GND through resistor R3 and capacitor C2 in sequence. At the same time, the other end of resistor R5 is also connected to pin 3 of the power amplifier IC1. Pin 3 of the power amplifier IC1 also outputs AMP_OUT_L signal to the speaker after passing through polar capacitor C5 and resistor R6 in sequence.

9. The guqin table sound amplification system according to claim 8, characterized in that: Pins 2 and 15 of the power amplifier IC1 are connected to VCC_12V+, VCC_12V+ is connected to GND through polarity capacitor C4, and pins 5 and 10 of the power amplifier IC1 are connected to GND through resistor R15.

10. A guqin table, characterized by: The guqin table sound amplification system described in any one of claims 1 to 9 is utilized.

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