CN102595298B

CN102595298B - Special sound amplifying system for stage

Info

Publication number: CN102595298B
Application number: CN201210016898.2A
Authority: CN
Inventors: 唐勇
Original assignee: NINGBO RIXING ELECTRONICS CO Ltd
Current assignee: NINGBO RIXING ELECTRONICS CO Ltd
Priority date: 2012-01-19
Filing date: 2012-01-19
Publication date: 2014-06-18
Anticipated expiration: 2032-01-19
Also published as: CN102595298A

Abstract

The invention discloses a special sound amplifying system for a stage. The system comprises a power supply processing unit circuit, a front input signal processing circuit and a module multi-channel amplification circuit, wherein the front input signal processing circuit and the module multi-channel amplification circuit are connected with a power supply. The system is characterized in that: the front input signal processing circuit comprises a circuit input unit, a universal serial bus/secure digital (USB/SD) unit and a stereo sound and super bass processing circuit, wherein a sound track selecting unit, a curve adjusting unit, a phase processing unit, an electronic card processing unit, a noise processing unit, an auxiliary output unit, a volume adjusting unit and a state indicating unit are arranged in the stereo sound and super bass processing circuit; an output end of the circuit input unit is connected with the auxiliary output unit and the sound track selecting unit; the sound track selecting unit is connected with the volume adjusting unit through the curve adjusting unit; and the electronic card processing unit and the curve adjusting unit are sequentially connected between an output end of the USB/SD unit and the volume adjusting unit. The special sound amplifying system for the stage is full in function, low in distortion, and safe and stable in work and multiple channels are realized.

Description

Special sound amplifying system for stage

Technical field

The present invention relates to a kind of sound reinforcement system, particularly Special sound amplifying system for stage.

Background technology

Because the comparison in equipment of stage public address is many, therefore connect cumbersome, just more difficult in build process, can not combine arbitrarily sound equipment, can only one the corresponding corresponding stereo set of sound reinforcement system, have to increase sound amplifier in order to reach better good effect, make the sound amplifier of stage many, simultaneously in use some equipment also exists the phenomenon of distortion, can not show the effect of original tonequality, in order not allow the sound reinforcement system of stage go wrong, in build process, to carry out audition, make it can in normal use procedure, not occur unnecessary problem, result of use is not high enough, the module of power amplifier is more single, in the time that peripheral signal has multiple input, can only then send into sound reinforcement system by peripheral signal changing system signal is carried out to public address, make the system of integration stage various, cause connecting complicated, take stage space.

Summary of the invention

The object of the invention is to provide in order to solve above-mentioned the deficiencies in the prior art a kind of function complete, connect simple, power is large, low in energy consumption, distortion is little, efficiency is high, work safety is stable, can meet the Special sound amplifying system for stage of the environment of various harshnesses.

To achieve these goals, the Special sound amplifying system for stage that the present invention is designed, the preposition input signal processing circuit that comprises power supply processing unit circuit and be connected with power supply and module multi-channel power amplifier circuit, it is characterized in that described preposition input signal processing circuit comprises circuit input unit, USB/SD unit and stereo and subwoofer treatment circuit, in described stereo and subwoofer treatment circuit, be provided with track selecting unit, curve adjustment unit, Phase Processing unit, electronic cards processing unit, noise processed unit, auxiliary output unit, sound volume regulation unit and state indication unit, the output of described circuit input unit is connected with auxiliary output unit and sound channel selected cell, and track selecting unit is connected with sound volume regulation unit by curve adjustment unit, between the output of described USB/SD unit and sound volume regulation unit, be connected with electronic cards processing unit and curve adjustment unit in turn.

Described Phase Processing unit is connected with curve adjustment unit; described state indication unit is connected with sound volume regulation unit; the output of described sound volume regulation unit is connected with module multi-channel power amplifier circuit; described module multi-channel power amplifier circuit comprises L channel CLASS D power amplifier unit, R channel CLASS D power amplifier unit and subwoofer CLASS D power amplifier unit, is connected with the protective circuit of overcurrent, short circuit, DC, overvoltage, under-voltage and temperature protection on module multi-channel power amplifier circuit.

Described power supply processing unit circuit is connected with respectively USB/SD unit, stereo and subwoofer treatment circuit, module multi-channel power amplifier circuit.

Described curve adjustment unit comprises left channel signals treatment circuit, right-channel signals treatment circuit and super low sound signal treatment circuit, be provided with L channel input circuit in described left channel signals treatment circuit, the one 180HZ high pass circuit, the one 140HZ high pass circuit, the one 100HZ high pass circuit, the first selector switch, the one 500HZ attenuator circuit, the one 4KHZ attenuator circuit and a 12KHZ promote circuit, and described super low sound signal treatment circuit comprises subwoofer sound channel input circuit, 50HZ promotes circuit, the second selector switch, 180HZ low pass circuit, 140HZ low pass circuit and 100HZ low pass circuit, described right-channel signals treatment circuit comprises R channel input circuit, the 2nd 180HZ high pass circuit, the 2nd 140HZ high pass circuit, the 2nd 100HZ high pass circuit, the 3rd selector switch, the 2nd 500HZ attenuator circuit, the 2nd 4KHZ attenuator circuit and the 2nd 12KHZ promote circuit, and described L channel input circuit is all connected with subwoofer sound channel input circuit with R channel input circuit.

The output of described L channel input circuit is connected in parallel to the input of a 180HZ high pass circuit, a 140HZ high pass circuit and a 100HZ high pass circuit, three end selecting sides of described the first selector switch connect respectively the output of a 180HZ high pass circuit, a 140HZ high pass circuit and a 100HZ high pass circuit, and the other end common port of the first selector switch is connected with a 500HZ attenuator circuit, a 4KHZ attenuator circuit and a 12KHZ in turn and promotes circuit.

The output of described subwoofer input circuit is connected with the input of 50HZ lifting circuit, 50HZ promotes the be connected in parallel input of 180HZ low pass circuit, 140HZ low pass circuit and 100HZ low pass circuit of the output of circuit, and the output of 180HZ low pass circuit, 140HZ low pass circuit and 100HZ low pass circuit is connected respectively three end selecting sides of the second selector switch.

The output of described R channel input circuit 13-23 is connected in parallel to the input of the 2nd 180HZ high pass circuit, the 2nd 140HZ high pass circuit and the 2nd 100HZ high pass circuit, three end selecting sides of described the 3rd selector switch connect respectively the output of the 2nd 180HZ high pass circuit, the 2nd 140HZ high pass circuit and the 2nd 100HZ high pass circuit, and the other end common port of the 3rd selector switch is connected with the 2nd 500HZ attenuator circuit, the 2nd 4KHZ attenuator circuit and the 2nd 12KHZ in turn and promotes circuit.

By the design of said structure, the most outstanding place of pre-process of circuit is to have increased curve adjustment cell mesh, can use audio amplifier and the subwoofer of various different sizes to carry out combination in any, and each channel sound can be controlled separately, each sound channel has increased Phase Processing unit simultaneously, allows music forever there is no distortion status, and power amplifier part adopts modular multichannel CLASS D power amplifier, make this circuit function complete, power is large, distortion low in energy consumption is little, efficiency is high, work safety is stable, can meet the environment of various harshnesses, therefore this combination sound reinforcement system is powerful, carry source of sound, single equipment can be realized multichannel work, stage public address is simplified, only needing a set of unit equipment is alternative traditional CD Player, power amplifier, the function that audio amplifier could be realized, power amplifier part has the CLASS D power amplifier of three sound channels, respectively left and right acoustic channels and subwoofer passage, subwoofer passage directly connects audio amplifier, left and right acoustic channels is external, the audio amplifier that can connect different size carries out combination in any by preposition curve switch.

The Special sound amplifying system for stage that the present invention obtains, many for current stage sound amplifier, connect trouble, moving and build the shortcomings such as difficulty designs, the most outstanding place of pre-process of circuit is to have increased curve adjustment cell mesh, can use the audio amplifier of various different sizes and subwoofer to carry out combination in any, and each channel sound can be controlled separately, increase the top restriction that disappears simultaneously, allowed music forever there is no distortion status.And power amplifier part adopts modular multichannel CLASS D power amplifier, make that this circuit function is complete, power is large, distortion low in energy consumption is little, and efficiency is high, and work safety is stable, can meet the environment of various harshnesses, therefore this combination sound reinforcement system is powerful, carries source of sound, and single equipment can be realized multichannel work, stage public address is simplified, and only needing a set of unit equipment is the function that alternative traditional CD Player, power amplifier, audio amplifier could realize.

Accompanying drawing explanation

Fig. 1 is the overall structure block diagram of embodiment;

Fig. 2 is the structured flowchart of curve adjustment part in Fig. 1;

Fig. 3 is the oscillogram of curve adjustment part in Fig. 2;

Fig. 4 is the circuit theory diagrams of Fig. 2.

In figure: preposition input signal processing circuit 1, power supply processing unit circuit 2, module multi-channel power amplifier circuit 3, peripheral output system unit 4, anti-interference process unit 5, circuit input unit 11, USB/SD unit 12, stereo and subwoofer treatment circuit 13, left channel signals treatment circuit 14, super low sound signal treatment circuit 15, right-channel signals treatment circuit 16, track selecting unit 13-1, curve adjustment unit 13-2, Phase Processing unit 13-3, electronic cards processing unit 13-4, noise processed unit 13-5, auxiliary output unit 13-6, sound volume regulation unit 13-7, state indication unit 13-8, L channel input circuit 13-21, the one 180HZ high pass circuit 13-24, the one 140HZ high pass circuit 13-25, the one 100HZ high pass circuit 13-26, the first selector switch 13-28, the one 500HZ attenuator circuit 13-29, the one 4KHZ attenuator circuit 13-210, the one 12KHZ promotes circuit 13-211, subwoofer sound channel input circuit 13-22, 50HZ promotes circuit 13-27, the second selector switch 13-215, 80HZ low pass circuit 13-212, 140HZ low pass circuit 13-213, 100HZ low pass circuit 13-214, R channel input circuit 13-23, the 2nd 180HZ high pass circuit 13-216, the 2nd 140HZ high pass circuit 13-217, the 2nd 100HZ high pass circuit 13-218, the 3rd selector switch 13-219, the 2nd 500HZ attenuator circuit 13-220, the 2nd 4KHZ attenuator circuit 13-221, the 2nd 12KHZ promotes circuit 13-222, L channel CLASS D power amplifier unit 32, R channel CLASS D power amplifier unit 33, subwoofer CLASS D power amplifier unit 34, protective circuit 31.

Embodiment

Below in conjunction with drawings and Examples, the present invention is further described.

Embodiment:

As Fig. 1, Fig. 2, shown in Fig. 4, Special sound amplifying system for stage provided by the invention, comprise power supply processing unit circuit 2 and the preposition input signal processing circuit 1 being connected with power supply and module multi-channel power amplifier circuit 3, preposition input signal processing circuit 1 comprises circuit input unit 11, USB/SD unit 12 and stereo and subwoofer treatment circuit 13, in stereo and subwoofer treatment circuit 13, be provided with track selecting unit 13-1, curve adjustment unit 13-2, Phase Processing unit 13-3, electronic cards processing unit 13-4, noise processed unit 13-5, auxiliary output unit 13-6, sound volume regulation unit 13-7 and state indication unit 13-8, the output of circuit input unit 11 is connected with auxiliary output unit 13-6 and sound channel selected cell 13-1, and track selecting unit 13-1 is connected with sound volume regulation unit 13-7 by curve adjustment unit 13-2, between the output of USB/SD unit 12 and sound volume regulation unit 13-7, be connected with electronic cards processing unit 13-4 and curve adjustment unit 13-2 in turn.

Phase Processing unit 13-3 is connected with curve adjustment unit 13-2; state indication unit 13-8 is connected with sound volume regulation unit 13-7; the output of sound volume regulation unit 13-7 is connected with module multi-channel power amplifier circuit 3; module multi-channel power amplifier circuit 3 comprises L channel CLASS D power amplifier unit 32, R channel CLASS D power amplifier unit 33 and subwoofer CLASS D power amplifier unit 34; module multi-channel power amplifier circuit 3 is connected with protective circuit 31, and described protective circuit 31 is to realize overcurrent, short circuit, direct current, overvoltage, under-voltage and temperature protection.

Power supply processing unit circuit 2 is connected with respectively USB/SD unit 12, stereo and subwoofer treatment circuit 13, module multi-channel power amplifier circuit 3.

Curve adjustment unit 13-2 comprises left channel signals treatment circuit 14, right-channel signals treatment circuit 16 and super low sound signal treatment circuit 15, be provided with L channel input circuit 13-21 in described left channel signals treatment circuit 14, the one 180HZ high pass circuit 13-24, the one 140HZ high pass circuit 13-25, the one 100HZ high pass circuit 13-26, the first selector switch 13-28, the one 500HZ attenuator circuit 13-29, the one 4KHZ attenuator circuit 13-210 and a 12KHZ promote circuit 13-211, and described super low sound signal treatment circuit 15 comprises subwoofer sound channel input circuit 13-22, 50HZ promotes circuit 13-27, the second selector switch 13-215, 80HZ low pass circuit 13-212, 140HZ low pass circuit 13-213 and 100HZ low pass circuit 13-214, described right-channel signals treatment circuit 16 comprises R channel input circuit 13-23, the 2nd 180HZ high pass circuit 13-216, the 2nd 140HZ high pass circuit 13-217, the 2nd 100HZ high pass circuit 13-218, the 3rd selector switch 13-219, the 2nd 500HZ attenuator circuit 13-220, the 2nd 4KHZ attenuator circuit 13-221 and the 2nd 12KHZ promote circuit 13-222, and described L channel input circuit 13-21 is connected with subwoofer sound channel input circuit 13-22 with R channel input circuit 13-23.

The output of L channel input circuit 13-21 is connected in parallel to a 180HZ high pass circuit 13-24, the input of the one 140HZ high pass circuit 13-25 and a 100HZ high pass circuit 13-26, the three end selecting sides of described the first selector switch 13-28 connect respectively a 180HZ high pass circuit 13-24, the output of the one 140HZ high pass circuit 13-25 and a 100HZ high pass circuit 13-26, the other end common port of the first selector switch 13-28 is connected with a 500HZ attenuator circuit 13-29 in turn, the one 4KHZ attenuator circuit 13-210 and a 12KHZ promote circuit 13-211.

The output of subwoofer input circuit 13-22 is connected with the input of 50HZ lifting circuit 13-27, the be connected in parallel input of 180HZ low pass circuit 13-212,140HZ low pass circuit 13-213 and 100HZ low pass circuit 13-214 of the output that 50HZ promotes circuit 13-27, and 180HZ low pass circuit 13-212,140HZ low pass circuit 13-213 and the output of 100HZ low pass circuit 13-214 are connected respectively the three end selecting sides of the second selector switch 13-215.

The output of R channel input circuit 13-23 is connected in parallel to the 2nd 180HZ high pass circuit 13-216, the input of the 2nd 140HZ high pass circuit 13-217 and the 2nd 100HZ high pass circuit 13-218, the three end selecting sides of the 3rd selector switch 13-219 connect respectively the 2nd 180HZ high pass circuit 13-216, the output of the 2nd 140HZ high pass circuit 13-217 and the 2nd 100HZ high pass circuit 13-218, the other end common port of selector switch (13-219) is connected with the 2nd 500HZ attenuator circuit 13-220 in turn, the 2nd 4KHZ attenuator circuit 13-221 and the 2nd 12KHZ promote circuit 13-222.

Specific works mode is: after inputting by civil power through anti-interference process unit 5, behind anti-interference process unit 5, send into power supply processing unit circuit 2, by giving respectively USB/SD unit 12 after power supply processing unit circuit 2 parts, stereo and subwoofer treatment circuit 13 and modular multichannel power amplifier 3 are powered, in stereo and subwoofer treatment circuit 13, by noise processed unit 13-5, this circuit is processed, because input pattern has two kinds: therefore can select as required different input signals: the first is in the time that peripheral signal is not audio signal, by selecting USB/SD unit 12 treatment circuits, after electronic cards processing unit 13-4, send into again curve adjustment unit 13-2 part, by curve adjustment unit, 13-2 sends into sound volume regulation unit 13-7, finally send into peripheral output system unit 4 by modular multichannel power amplifier 3, it two is after peripheral audio signal is by circuit input unit 11, to send into track selecting unit 13-1 part after curve adjustment unit 13-2 part, to be connected with sound volume regulation unit 13-7 again, finally sends into by modular multichannel power amplifier 3 and sends into peripheral output system unit 4, auxiliary output unit 13-6 connection line input unit 11 can connect by auxiliary output unit 13-6 in the time that periphery also needs to connect external output, has realized diversification.These two kinds of mode common ground are to be all then connected through curve adjustment unit 13-2 the modular multichannel power amplifier 3 of finally making a gift to someone with sound volume regulation unit 13-7 to send into peripheral output system unit 4, in curve adjustment unit 13-2, carry out the phase place of adjustment curve regulon 13-3 by Phase Processing unit 13-3, show the control to sound volume regulation unit in sound volume regulation unit 13-7 part by state indication unit 13-8.

As Fig. 2, shown in Fig. 3, in curve adjustment unit 13-2, mode that can be different according to different track selecting is carried out array output, make to select different sound equipments, if external power amplifier is L channel output, signal is just selected left channel signals treatment circuit 14, this circuit is by selecting the adjusting of the first selector switch 13-28, three kinds of selection modes can be selected, Article 1, the output waveform of selection mode is waveform c, it is to select after a 180HZ high pass circuit 13-24 more successively through a 500HZ attenuator circuit 13-29, the one 4KHZ attenuator circuit 13-210 and a 12KHZ promote circuit 13-211, the output waveform of Article 2 selection mode is waveform b, it is to select after a 140HZ high pass circuit 13-25 more successively through more successively through a 500HZ attenuator circuit 13-29, the one 4KHZ attenuator circuit 13-210 and a 12KHZ promote circuit 13-211, the output waveform of Article 3 selection mode is waveform a, it is to select after a 100HZ high pass circuit 13-26 more successively through a 500HZ attenuator circuit 13-29, the one 4KHZ attenuator circuit 13-210 and a 12KHZ promote circuit 13-211.

If external power amplifier is R channel output, signal is just selected right-channel signals treatment circuit 16, this circuit is by the adjusting of the 3rd selector switch 13-219, three kinds of selection modes can be selected, Article 1, the output waveform of selection mode is waveform j, it is to select after the 2nd 180HZ high pass circuit 13-216 more successively through the 2nd 500HZ attenuator circuit 13-220, the 2nd 4KHZ attenuator circuit 13-221 and the 2nd 12KHZ promote circuit 13-222, the output waveform of Article 2 selection mode is waveform i, it is to select after the 2nd 140HZ high pass circuit 13-217 more successively through the 2nd 500HZ attenuator circuit 13-220, the 2nd 4KHZ attenuator circuit 13-221 and the 2nd 12KHZ promote circuit 13-222, the output waveform that Article 3 selection mode is is waveform h, it is to select after the 2nd 100HZ high pass circuit 13-218 more successively through the 2nd 500HZ attenuator circuit 13-220, the 2nd 4KHZ attenuator circuit 13-221 and the 2nd 12KHZ promote circuit 13-222.

But some super low sound signal can be sent into super low sound signal treatment circuit 15 in selecting L channel and R channel, this circuit is by the adjusting of the second selector switch 13-215, three kinds of selection modes can be selected, Article 1, the output waveform of selection mode is waveform g, and it is to pass through successively 180HZ low pass circuit 13-212 after selecting 50HZ to promote circuit 13-27 again; The output waveform of Article 2 selection mode is waveform f, and it is to pass through successively 140HZ low pass circuit 13-213 after selecting 50HZ to promote circuit 13-27 again; The output waveform of Article 3 selection mode is waveform e; it is to pass through successively 100HZ low pass circuit 13-214 after selecting 50HZ to promote circuit 13-27 again; super low sound signal is by the rear connection mode blocking multi-channel power amplifier 3 of output after three selecting paths; in modular multichannel power amplifier 3, by protective circuit 31, circuit is realized to defencive function.

Claims

1. a Special sound amplifying system for stage, the preposition input signal processing circuit (1) that comprises power supply processing unit circuit (2) and be connected with power supply and module multi-channel power amplifier circuit (3), it is characterized in that described preposition input signal processing circuit (1) comprises circuit input unit (11), USB/SD unit (12) and stereo and subwoofer treatment circuit (13), in described stereo and subwoofer treatment circuit (13), be provided with track selecting unit (13-1), curve adjustment unit (13-2), Phase Processing unit (13-3), electronic cards processing unit (13-4), noise processed unit (13-5), auxiliary output unit (13-6), sound volume regulation unit (13-7) and state indication unit (13-8), the output of described circuit input unit (11) is connected with auxiliary output unit (13-6) and sound channel selected cell (13-1), and track selecting unit (13-1) is connected with sound volume regulation unit (13-7) by curve adjustment unit (13-2), between the output of described USB/SD unit (12) and sound volume regulation unit (13-7), be connected with electronic cards processing unit (13-4) and curve adjustment unit (13-2) in turn, described Phase Processing unit (13-3) is connected with curve adjustment unit (13-2), described state indication unit (13-8) is connected with sound volume regulation unit (13-7), the output of described sound volume regulation unit (13-7) is connected with module multi-channel power amplifier circuit (3), described module multi-channel power amplifier circuit (3) comprises L channel CLASS D power amplifier unit (32), R channel CLASS D power amplifier unit (33) and subwoofer CLASS D power amplifier unit (34), described module multi-channel power amplifier circuit (3) is connected with overcurrent, short circuit, DC, overvoltage, the protective circuit (31) of under-voltage and temperature protection, described power supply processing unit circuit (2) is connected with respectively USB/SD unit (12), stereo and subwoofer treatment circuit (13) and module multi-channel power amplifier circuit (3).

2. Special sound amplifying system for stage according to claim 1, is characterized in that described curve adjustment unit (13-2) comprises left channel signals treatment circuit (14), right-channel signals treatment circuit (16) and super low sound signal treatment circuit (15), in described left channel signals treatment circuit (14), be provided with L channel input circuit (13-21), the one 180HZ high pass circuit (13-24), the one 140HZ high pass circuit (13-25), the one 100HZ high pass circuit (13-26), the first selector switch (13-28), the one 500HZ attenuator circuit (13-29), the one 4KHZ attenuator circuit (13-210) and a 12KHZ promote circuit (13-211), the output of wherein said L channel input circuit (13-21) is connected in parallel to a 180HZ high pass circuit (13-24), the input of the one 140HZ high pass circuit (13-25) and a 100HZ high pass circuit (13-26), three end selecting sides of described the first selector switch (13-28) connect respectively a 180HZ high pass circuit (13-24), the output of the one 140HZ high pass circuit (13-25) and a 100HZ high pass circuit (13-26), the other end common port of the first selector switch (13-28) is connected with a 500HZ attenuator circuit (13-29) in turn, the one 4KHZ attenuator circuit (13-210) and a 12KHZ promote circuit (13-211), described super low sound signal treatment circuit (15) comprises subwoofer sound channel input circuit (13-22), 50HZ promotes circuit (13-27), the second selector switch (13-215), 180HZ low pass circuit (13-212), 140HZ low pass circuit (13-213) and 100HZ low pass circuit (13-214), the output of wherein said subwoofer input circuit (13-22) is connected with the input of 50HZ lifting circuit (13-27), 50HZ promotes the output 180HZ low pass circuit (13-212) that is connected in parallel of circuit (13-27), the input of 140HZ low pass circuit (13-213) and 100HZ low pass circuit (13-214), and 180HZ low pass circuit (13-212), 140HZ low pass circuit (13-213) and the output of 100HZ low pass circuit (13-214) are connected respectively three end selecting sides of the second selector switch (13-215), described right-channel signals treatment circuit (16) comprises R channel input circuit (13-23), the 2nd 180HZ high pass circuit (13-216), the 2nd 140HZ high pass circuit (13-217), the 2nd 100HZ high pass circuit (13-218), the 3rd selector switch (13-219), the 2nd 500HZ attenuator circuit (13-220), the 2nd 4KHZ attenuator circuit (13-221) and the 2nd 12KHZ promote circuit (13-222), the output of wherein said R channel input circuit (13-23) is connected in parallel to the 2nd 180HZ high pass circuit (13-216), the input of the 2nd 140HZ high pass circuit (13-217) and the 2nd 100HZ high pass circuit (13-218), three end selecting sides of described the 3rd selector switch (13-219) connect respectively the 2nd 180HZ high pass circuit (13-216), the output of the 2nd 140HZ high pass circuit (13-217) and the 2nd 100HZ high pass circuit (13-218), the other end common port of selector switch (13-219) is connected with the 2nd 500HZ attenuator circuit (13-220) in turn, the 2nd 4KHZ attenuator circuit (13-221) and the 2nd 12KHZ promote circuit (13-222), described L channel input circuit (13-21) is all connected with subwoofer sound channel input circuit (13-22) with R channel input circuit (13-23).