CN1276959A - Post-amplification stereophonic to surround sound decoding circuit - Google Patents

Abstract

A post-amplification stereophonic to surround sound decoding circuit is described herein. The decoding circuit includes inputs to be connected to a stereophonic power amplifier to receive a powered amplified stereophonic signal and outputs to be connected to left and right main loudspeakers, to left and right secondary loudspeakers and to a central loudspeaker. The decoding circuit includes secondary channels decoding circuit decoding left and right surround channel signals to be supplied to the left and right secondary loudspeakers, respectively, and a central channel decoding circuit decoding a central channel signal to be supplied to the central loudspeaker. The central channel decoding circuit includes two decoupling capacitors decoupling the left and right signals from the powered amplified sterepohonic signal before combining these signals to yield the central channel signal. This decoupling action prevents "bleeding" of the left and right signals that would degrade the stereophonic signal.

Description

Amplified stereo-surround sound decoding circuit

The present invention relates to a stereo-surround decoding circuit. Specifically, the present invention relates to an amplified stereo-surround decoding circuit installed between a conventional stereo amplifier and a conventional speaker.

While mono is still widely used in amplitude modulated (AM) radio and telephone networks, stereo is now considered the standard in high-fidelity (Hi-Fi) applications.

The purpose of a stereophonic system is to reproduce two different sound channels through speakers so that the sound reaching each ear of the listener gives the listener the impression that he is at the location where the recording was made. Of course, giving this impression depends on many factors, such as the position of the listener relative to the speakers and the quality of the recording.

Surround sound systems, now known as home theaters, have been introduced in home electronics to immerse the listener in an environment of different sounds from several locations in the room. A standard home theater surround sound system has five speakers, each reproducing its own sound channel.

Surround sound decoding circuits used in surround sound systems can generally be divided into two types, namely, pre-amplification decoding circuits and post-amplification decoding circuits.

A surround sound system using a pre-amplification decoding circuit receives a traditional low-level two-channel stereo signal and expands it into a five-channel surround sound. These five sound channels are respectively amplified and added to the respective predetermined speakers. The five channels are usually defined as:

Main left channel, corresponding to the left channel of the stereo signal, reproduced by a front left speaker;

Main right channel, corresponding to the right channel of the stereo signal, reproduced by a front right speaker;

The sub-left channel, also known as the left surround channel, is obtained by decoding the main left channel minus the main right channel, and is reproduced by a rear left speaker;

Sub Right, also known as Surround Right, decoded by subtracting Main Left from Main Right, reproduced by a single rear speaker; and

The center channel, obtained by decoding the main left and right channels together, is reproduced by a center speaker usually placed on top of the TV screen.

The main disadvantage of a surround sound system using a pre-amplified decoder is that a five-channel amplifier is necessary to reproduce the surround sound, because the power amplification is performed after the surround sound is produced from the stereo decoding. Therefore, users who adopt this technology must configure a dedicated power amplifier, which increases the cost of the system.

Post-amplification surround sound decoders generally overcome the aforementioned disadvantages of pre-amplification decoders by providing a device that can be installed between the left and right power-amplified stereo signal outputs of a conventional stereo amplifier and the five above-mentioned speakers. Therefore, stereo-surround decoding is performed after power amplification, which allows the use of conventional stereo amplifiers.

US Patent No. 5,265,166 "Multi-Channel Sound Simulation System" issued to Madnick et al. on November 23, 1993 discloses such an amplified stereo-surround decoder. The main disadvantage of the system disclosed by Madnick et al. is that it generally results in a reduction in the quality of the sound reproduction and an increase in the complexity of the loading effect on the stereo amplifier. As is readily understood by those familiar with the art, returning the negative terminal of the rear speaker to ground will cause the amplifier output to "see" an impedance other than the traditional 8 ohm speaker impedance. In addition, returning the negative terminal of the center speaker to the ground through an inductor will also increase the complexity of the power amplifier load, which will inevitably lead to increased sound distortion and poor overall sound reproduction. It should also be noted that resistively combining the left and right channels to create a center channel will degrade the intelligibility of the main left and right channels because there is no way to prevent the left and right channels from leaking into each other.

U.S. Patent No. 5,497,425 "Multi-Channel SurroundSound Simulation Device" issued to Robert J. Rapoport on March 5, 1996 discloses a composite stereo-surround sound decoder, It has the characteristics of the above-mentioned pre-amplification and post-amplification decoding schemes. The system proposed by Rapoport also has a number of disadvantages. For example, an auxiliary power amplifier must be configured to amplify the center channel and then sent to the center speaker for reproduction. Furthermore, the disadvantages discussed above for the system of Madnick et al. generally also exist for the system of Rapoport, since the rationale for the design is similar.

It is therefore an object of the present invention to provide an improved amplified stereo-surround decoding arrangement which does not have the above-mentioned disadvantages of the prior art.

Specifically, according to the present invention, the provided amplified stereo-surround decoding circuit includes:

an input receiving a power amplified stereo signal comprising a left channel signal and a right channel signal;

a first output configured to be connected to a sub-left speaker;

a second output configured to be connected to a sub-right speaker;

a third output configured to connect to a center speaker;

A sub-channel decoding device for decoding a sub-left channel signal and a sub-right channel signal from the left and right channel signals of the power-amplified stereo signal, and the sub-left channel signal is sent to the first output terminal, And the sub-right channel signal is sent to the second output terminal; and

A central channel decoding device for decoding a central channel signal from the left and right channel signals of the power-amplified stereo signal, which includes first and second decoupling devices for decoding the left and right channel signals, respectively, It also includes a device for combining the decoupled left and right channel signals into a central channel signal and sending it to the third output terminal, so that the decoupling device of the central channel decoding device makes the left and right channel signals of the stereo signal amplified by power Can be merged without changing the original left and right channel signals.

According to another implementation of the present invention, the provided amplified stereo-surround decoding circuit includes:

an input receiving a power amplified stereo signal comprising a left channel signal and a right channel signal;

a first output configured to be connected to a sub-left speaker;

a second output configured to be connected to a sub-right speaker;

a third output configured to connect to a center speaker;

a fourth output configured to connect to a main left loudspeaker;

a fifth output configured to connect to a main right speaker;

A sub-channel decoding device for decoding a sub-left channel signal and a sub-right channel signal from the left and right channel signals of the amplified main sound signal, and the sub-left channel signal is sent to the first output terminal , and the sub-right channel signal is sent to the second output terminal;

A center channel decoding device for decoding a center channel signal from the left and right channel signals of the power amplified stereo signal, which includes first and second decoupling means for decoupling the left and right channel signals respectively , also includes a device for combining the decoupled left and right channel signals into a center channel signal and sending it to the third output terminal; and

main channel volume control means for controlling (a) the amplitude of the left channel signal to the fourth output and (b) the amplitude of the right channel signal to the fifth output,

Therefore, the decoupling device of the center channel decoding device enables the left and right channel signals of the power amplified stereo signal to be combined without changing the original left and right channel signals.

According to yet another implementation of the present invention, the center channel decoding circuit of the provided amplified stereo-surround sound decoding device includes:

an input terminal for receiving a power-amplified stereo signal comprising a left channel signal and a right channel signal;

an output configured to connect to a center speaker; and

A center channel decoding device for decoding a center channel signal from the left and right channel signals of the power amplified stereo signal, which includes first and second decoupling means for decoupling the left and right channel signals respectively , also includes a device for combining the decoupled left and right channel signals into a center channel signal and sending it to the output terminal, so that the decoupling device of the center channel decoding device makes the left and right channel signals of the stereo signal amplified by power Can be merged without changing the original left and right channel signals.

Other objects and advantages of the present invention will be apparent to those skilled in the art from the following non-limiting description of preferred embodiments with reference to the accompanying drawings.

In these drawings:

Fig. 1 shows the amplified stereo-surround sound decoding circuit designed by an embodiment of the present invention in the form of a block diagram, this decoding circuit is connected between a stereo power amplifier and five loudspeakers;

Fig. 2 shows the amplified stereo-surround sound decoding circuit in Fig. 1 in the form of a schematic diagram; and

FIG. 3 shows another embodiment of the center channel decoding circuit in FIG. 2 in the form of a schematic diagram.

The amplified stereo-surround sound decoding circuit 10 will be described below with reference to FIG. 1 and FIG. 2 .

As shown in FIG. 1 , the decoding circuit 10 is connected to a stereo power amplifier 12 . The decoding circuit 10 includes a left input terminal 14 , a right input terminal 16 and a ground terminal 18 , respectively connected to the left output terminal 20 , the right output terminal 22 and the ground terminal 24 of the stereo power amplifier 12 . Of course, the connection points 20, 22 and 24 of the power amplifier 12 are conventionally connected to the conventional main left and main right speakers.

The decoding circuit 10 also includes 2 main left loudspeaker output terminals 26,27 connected with the main left loudspeaker 28, 2 main right loudspeaker output terminals 30,31 connected with the main right loudspeaker 32, and 2 terminals connected with the auxiliary left loudspeaker 36 Sub-left speaker output terminals 34, 35, 2-terminal sub-right speaker output terminals 38, 39 connected to sub-right speaker 40, and 2-terminal center speaker output terminals 42, 43 connected to center speaker 44.

The decoding circuit 10 includes a main channel volume control circuit 46 , a sub channel decoding circuit 48 and a center channel decoding circuit 50 .

As can be seen from Fig. 1, the main channel volume control circuit 46 is connected between the input terminals 14, 16 and 18 and the main speaker output terminals 26, 27, 30 and 31, and the secondary channel decoding circuit 48 is connected between the input terminals 14 and 16 and Between the sub speaker output terminals 34, 35, 38 and 39, and the center channel decoding circuit 50 is connected between the input terminals 14, 16 and 18 and the center speaker output terminals 42 and 43.

Circuits 46, 48 and 50 will be described in detail below with reference to FIG.

The main channel volume control circuit 46 includes a variable resistor 52 connected between the left input terminal 14 and the output terminal 26 connected to the main left loudspeaker, and a variable resistor 52 connected between the right input terminal 16 and the output terminal 30 connected to the main right loudspeaker variable resistor 54 between. By changing the resistance of resistors 52 and 54, the amplitude of the signal applied to the main speaker can be adjusted, thereby changing the volume of the sound reproduced by the main speaker, because this changes the way the amplified signal is dissipated as heat in the resistors. partial power. It can be seen from FIG. 2 that the ground terminals 27 and 31 are connected to each other and connected to the input ground terminal 18 together.

It should be noted that variable resistors 52 and 54 may advantageously be combined together in the form of a stereo L attenuator (ungrounded), with appropriate power ratings. If this is the case, the actor will be faced with only one volume control for the two main speakers. In addition, the two variable resistors can also be realized by a set of high-quality discrete resistors (not shown) and switches (not shown), or by a high-power variable resistor integrated circuit (not shown).

Therefore, it should be noted that, here and in the appended claims, the so-called "variable resistor" refers to any resistive electronic device or structure and/or other electronic device that can change the resistance between two points of the circuit.

The sub-channel decoding circuit 48 includes a first capacitor 56 connected between the left input terminal 14 and the output terminal 34 connected to the sub-left speaker, a first capacitor 56 connected between the right input terminal 16 and the sub-right speaker and the output terminal 38 Between the second capacitor 58 and a variable resistor 60 connected between the output ground terminal 35 connected to the sub-left speaker and the output ground terminal 39 connected to the sub-right speaker. It should be noted that the output grounds 35 and 39 are not connected to the input ground 18 .

As will be seen by those skilled in the art, a variable resistor 60 connected between output grounds 35 and 39 enables the two sub-speakers to be reproduced by subtracting the signals sent to inputs 14 and 16, respectively. The obtained respective sub-channel signals. Specifically, the sub-left channel signal reproduced by the sub-left speaker is the signal supplied to the left input terminal 14 minus the signal supplied to the right input terminal 16 . Similarly, the sub right channel signal reproduced by the sub right speaker is the signal applied to the right input 16 minus the signal applied to the left input 14 . Since the sub channel decoding circuit 48 is not connected to ground, the sub left and sub right channel signals are equal since input 16 minus input 14 is equal to input 14 minus input 16 . In addition, since the capacitors 56 and 58 are decoupling capacitors in a sense, and since the sub-channel decoding circuit 48 is not grounded, the interconnected pair of ground terminals 35 and 39 is added to the main channel volume control circuit 46 and to the The signal from center channel decoding circuit 50 will have no adverse effect because capacitors 56 and 58 prevent the signal applied to input 14 from "leaking" into the signal applied to input 16 and vice versa.

By changing the resistance value of the resistor 60, the amplitude of the signal applied to the sub-speaker can be adjusted, thereby changing the volume of the sound reproduced by the sub-speaker, because the portion of the power-amplified signal dissipated on the resistor as heat is changed power.

It has been found to be advantageous to select the capacitances of capacitors 56 and 58 so that together with the impedance of the sub-speaker they form a high-pass filter of around 100 Hz.

The center channel decoding circuit 50 includes a first fixed resistance resistor 62 connected to the left input terminal 14, a first capacitor 64 connected to the first resistor 62, and a second fixed resistance resistor connected to the right input terminal 16 66. A second capacitor 68 connected to the second resistor 66 and a variable resistor 70 connected between the capacitors 64 and 68 and the output 42 connected to the center speaker. The ground terminal 43 is connected to the input ground terminal 18 .

Thus, the signal applied to the center speaker output 42 is the sum of the signals applied by the power amplifier 12 to the left and right inputs 14 and 16 .

It should be noted that since capacitors 64 and 68 are decoupling capacitors in a sense, the interconnection of the outputs of these two capacitors so that summing the left and right inputs 14 and 16 has no effect on the input to the main channel volume control Circuit 46 and the signal applied to sub-channel decoding circuit 48 have adverse effects.

It has been found to be advantageous to choose the values of the fixed resistors 62 and 64 so that they are each one-half the nominal impedance of the main loudspeaker. It has also been found to be advantageous to choose the sizes of capacitors 64 and 68 so that together with the impedance of the center speaker they form a high pass filter at around 100 Hz.

Likewise, by varying the resistance of resistor 70, the amplitude of the signal applied to the center speaker can be adjusted, thereby changing the volume of the sound reproduced by the center speaker, as the adjusted power amplified signal is dissipated as heat across the resistor that part of the power.

It should be noted that variable resistors 60 and 70 may advantageously be realized as separate mono L attenuators (ungrounded), with appropriate power ratings. In addition, variable resistors 60 and 70 can also be implemented with a set of high-quality discrete resistors (not shown) and switches (not shown), or can be implemented with a high-power variable resistor integrated circuit (not shown).

Another center channel decoding circuit 150 will be briefly described below with reference to FIG. 3 . The main difference between the decoding circuit 150 and the decoding circuit 50 in FIG. 2 is that the variable resistor 70 configured after the left and right input interconnection is replaced by a pair of variable resistors 170, 170′, which are respectively configured in the fixed resistance resistor 62, 66 and capacitors 64, 68, so it is configured before the left and right input interconnection. Decoding circuit 150 improves impedance and frequency stability, and makes more power available to the center speaker.

Also, it should be noted that variable resistors 170 and 170' may advantageously be combined together in the form of a stereo L attenuator (ungrounded), with appropriate power ratings. In addition, the two variable resistors can also be realized by a set of high-quality discrete resistors (not shown) and switches (not shown), or by a high-power variable resistor integrated circuit (not shown).

Returning to FIG. 2, it should be noted that the impedance of the amplified stereo-surround decoding circuit 10 "sees" by the outputs 20, 22 and 24 of the power amplifier 12 is substantially the same as the impedance of the main speaker because the decoding circuit Both the 48 and 50 use decoupling capacitors, so are effectively "invisible" in terms of impedance. Indeed, the impedance of the decoding circuits 48 and 50 is much higher than that of the main speakers 28 and 32 which are normally connected in parallel with them, so that the impedance seen by the outputs 20, 22 and 24 of the power amplifier does not change significantly.

As shown in FIG. 2 , fuses 72 , 74 , 76 are connected between the input terminals 14 , 16 , 18 and the circuits 46 , 48 , 50 for circuit protection. It should also be noted that an on-off switch (not shown) may advantageously be configured to decouple circuits 48 and 50 from inputs 14, 16, 18 when the user wishes to use only the main speakers and not hear surround sound. disconnect.

It has been found that non-polarized capacitors are required for the decoding capacitors of the present invention. Of course, matched polarized capacitor pairs could also be used instead, as is well known to those skilled in the art.

It should be noted that although the above circuits 46, 48, 50 are illustrated as discrete circuits, these circuits may advantageously be implemented together on a printed circuit board (not shown).

As will be appreciated by those skilled in the art, the circuits 46, 48, 50 described above in connection with Fig. 2 are given as examples only and may be modified in accordance with the spirit of the present invention. It should also be noted that each circuit can have a volume control, allowing the user to adjust the volume of each of the three groups of speakers: main, sub, and center. Indeed, it has been found that some users prefer to hear the surround channels (reproduced by the sub speaker) and the center channel (reproduced by the center speaker) at a louder or lower volume than is considered optimal. Furthermore, since the decoding circuit 10 can be connected to several different power amplifiers and to several different speakers, independent volume controls help to compensate for these differences. However, the variable resistors 52, 54, 60 and 70 (or 170, 170') may be omitted for a simpler and more economical amplified stereo-surround decoding circuit. Also, fuses 72, 74 and 76 can be omitted from the circuit since these fuses do nothing more than provide overload protection. Note that such a simplified circuit (not shown) is less versatile because the user has no means of independently controlling the three sets of speakers.

It should be pointed out that even though the amplified stereo-surround sound decoding circuit 10 described above includes respective output terminals connected to the main left and main right loudspeakers, for those familiar with this technical field, it is necessary to connect the decoder with a In case a power amplifier providing two pairs of left and right output terminals is used in conjunction, it can be designed as a decoding device (not shown) without these output terminals. Indeed, one pair of outputs could be routed directly to the main left and main right loudspeakers, while another pair could be routed to this decoder to give sub left, sub right and center outputs as described above. Of course, this kind of decoding device has poor versatility, because there is no means of independently controlling the signal applied to the main speaker, and this circuit can only be used with the above-mentioned power amplifier or with multiple speakers with a common floating ground. The integrated amplifier is used together.

It should also be noted that such amplified stereo-surround decoding circuit 10 may advantageously be housed in a box provided with suitable connectors for the input and output terminals of circuit 10, forming an amplified stereo-surround decoding device . Preferably, the adjusters for the variable resistors 52, 54, 60 and 70 are located within easy reach of the user. In addition, the decoding circuit 10 can be installed in a conventional power amplifier, so that a surround sound power amplifier which does not require five amplification channels can be obtained.

Finally, it should be noted that output pairs 34 and 35, 38 and 39, 42 and 43 can be provided with suitable switching devices (not shown) so that the polarity of these output pairs can be reversed. Indeed, selectively inverting these pairs allows the user to make adjustments to the surround sound reproduction.

As can be seen by those familiar with this technical field, the amplified stereo-surround sound decoding circuit of the present invention has many advantages compared with the stereo-surround sound decoding circuit of the prior art, for example:

Decoding is performed after power amplification, thus allowing the user to still use his traditional stereo power amplifier;

The decoding circuit is compatible with everyday electrical appliances and professional speakers;

The decoding circuit is compatible with daily electrical appliances and professional audio power amplifiers;

The decoding circuit enables the user to adjust his listening effect by changing the volume of the three groups of speakers independently;

Decoding is compatible with various known two-channel hybrid coding standards, such as home theater surround sound developed by Dolby Laboratories and Pro_Logic ^TM technology and THX ^TM technology developed by Lucas Arts Entertainment;

The decoding circuit does not require an additional power supply;

The decoding circuit provides a fairly wide frequency band for the center and surround channels;

Decoding circuits can be easily designed to suit unique and complex loudspeaker impedance loads;

Decoding circuits can be easily designed to handle high power signals by providing devices with appropriate power ratings;

Decoding circuits can be easily designed for different applications, such as multimedia computing, car audio systems, virtual reality applications; and

The decoding circuit can easily be designed with a computer controlled interface to control individual volumes, for example if this particular decoding circuit is to be used by a computer controlled application.

Although the invention has been described above in connection with a preferred embodiment of the invention, the preferred embodiment can be modified as required without departing from the spirit of the invention as defined in the appended claims.

Claims (25)

1. stereo-surround sound decoding circuit after the amplification comprises:

Reception is through the input of the stereophonic signal that comprises a left channel signals and a right-channel signals of power amplification;

One is configured to first output that is connected with a secondary left speaker;

One is configured to second output that is connected with a right loud speaker of pair;

One is configured to the 3rd output that is connected with a center loudspeaker;

Go out the secondary channel decoding device of a secondary left channel signals and a secondary right-channel signals from left and right sound channels signal decoding through the stereophonic signal of power amplification, described secondary left channel signals is delivered to described first output, and described secondary right-channel signals is delivered to described second output; And

Go out the center channel decoding device of a center channel signal from left and right sound channels signal decoding through the stereophonic signal of power amplification, described center channel decoding device comprises the first and second decoupling zero devices that respectively the left and right sound channels signal carried out decoupling zero, also comprise the device that is merged into described center channel signal through the left and right sound channels signal of decoupling zero with described, described center channel signal is delivered to described the 3rd output

Thereby the described decoupling zero device of described center channel decoding device can merge the left and right sound channels signal through the stereophonic signal of power amplification and can not change original left and right sound channels signal.

One kind as in claim 1 stereo-surround sound decoding circuit after the amplification of defined, wherein said center channel decoding device also comprises the device of the amplitude of controlling described center channel signal.

One kind as in claim 2 stereo-surround sound decoding circuit after the amplification of defined, wherein said amplitude control unit comprises at least one variable resistor.

One kind as in claim 1 stereo-surround sound decoding circuit after the amplification of defined, the described first and second decoupling zero devices of wherein said center channel decoding device comprise first and second electric capacity respectively.

One kind as in claim 4 stereo-surround sound decoding circuit after the amplification of defined, the wherein said first decoupling zero device comprises first resistance with described first capacitances in series, be connected to described input and receive described left channel signals, and the described second decoupling zero device comprises second resistance with described second capacitances in series, be connected to described input and receive described right-channel signals, described first and second electric capacity are interconnected, and will be merged into described center channel signal through the left channel signals of decoupling zero with through the right-channel signals of decoupling zero.

One kind as in claim 1 stereo-surround sound decoding circuit after the amplification of defined, wherein said secondary channel decoding device comprises the first and second decoupling zero devices that respectively described left and right sound channels signal carried out decoupling zero.

One kind as in claim 6 stereo-surround sound decoding circuit after the amplification of defined, the described first and second decoupling zero devices of wherein said secondary channel decoding device comprise first and second electric capacity respectively, described first electric capacity is connected between described input and described first output, and described second electric capacity is connected between described input and described second output.

One kind as in claim 6 stereo-surround sound decoding circuit after the amplification of defined, wherein said first and second outputs respectively comprise an earth terminal, and described secondary channel decoding device also comprises a variable resistor between the described earth terminal that is connected on described first and second outputs.

9. stereo-surround sound decoding circuit after the amplification comprises:

Reception is through the input of the stereophonic signal that comprises a left channel signals and a right-channel signals of power amplification;

One is configured to first output that is connected with a secondary left speaker;

One is configured to second output that is connected with a right loud speaker of pair;

One is configured to the 3rd output that is connected with a center loudspeaker;

One is configured to the 4th output that is connected with a main left speaker;

One is configured to the 5th output that is connected with a right loud speaker of master;

Go out the secondary channel decoding device of a secondary left channel signals and a secondary right-channel signals from stereophonic signal left and right sound channels signal decoding through power amplification, described secondary left channel signals is delivered to described first output, and described secondary right-channel signals is delivered to described second output;

Go out the center channel decoding device of a center channel signal from left and right sound channels signal decoding through the stereophonic signal of power amplification, described center channel decoding device comprises the first and second decoupling zero devices that respectively the left and right sound channels signal carried out decoupling zero, also comprise being merged into the device of described center channel signal with described through the left and right sound channels signal of decoupling zero, described center channel signal is delivered to described the 3rd output; And

Control (a) left channel signals deliver to the amplitude of the 4th output and (b) right-channel signals deliver to the main sound channel sound volume control device of the amplitude of the 5th output,

Thereby the described decoupling zero device of described center channel decoding device can merge the left and right sound channels signal through the stereophonic signal of power amplification and can not change original left and right sound channels signal.

One kind as in claim 9 stereo-surround sound decoding circuit after the amplification of defined, wherein said center channel decoding device also comprises the device of the amplitude of controlling described center channel signal.

11. one kind as in claim 10 stereo-surround sound decoding circuit after the amplification of defined, wherein said amplitude control unit comprises at least one variable resistor.

12. one kind as in claim 9 stereo-surround sound decoding circuit after the amplification of defined, the described first and second decoupling zero devices of wherein said center channel decoding device comprise first and second electric capacity respectively.

13. one kind as stereo-surround sound decoding circuit after the amplification of defined in claim 12, the wherein said first decoupling zero device comprises first resistance with described first capacitances in series, be connected to described input and receive described left channel signals, and the described second decoupling zero device comprises second resistance with described second capacitances in series, be connected to described input and receive described right-channel signals, described first and second electric capacity are interconnected, and will be merged into described center channel signal through the left channel signals of decoupling zero with through the right-channel signals of decoupling zero.

14. one kind as in claim 9 stereo-surround sound decoding circuit after the amplification of defined, wherein said secondary channel decoding device comprises the first and second decoupling zero devices that respectively described left and right sound channels signal carried out decoupling zero.

15. one kind as stereo-surround sound decoding circuit after the amplification of defined in claim 14, the described first and second decoupling zero devices of wherein said secondary channel decoding device comprise first and second electric capacity respectively, described first electric capacity is connected between described input and described first output, and described second electric capacity is connected between described input and described second output.

16. one kind as stereo-surround sound decoding circuit after the amplification of defined in claim 14, wherein said first and second outputs respectively comprise an earth terminal, and described secondary channel decoding device also comprises a variable resistor between the described earth terminal that is connected on described first and second outputs.

17. one kind as stereo-surround sound decoding circuit after the amplification of defined in claim 9, wherein said main sound channel sound volume control device comprises (a) one first variable resistor, connects into to described the 4th output with described the 4th output and described input and presents described left channel signals; And (b) the second adjustable resistance, connect into to described the 5th output with described the 5th output and described input and to present described right-channel signals.

18. a center channel decoding circuit that is used to amplify afterwards stereo-surround sound decoding device comprises:

Reception is through the input of the stereophonic signal that comprises a left channel signals and a right-channel signals of power amplification;

One is configured to the output that is connected with a center loudspeaker; And

Go out the center channel decoding device of a center channel signal from left and right sound channels signal decoding through the stereophonic signal of power amplification, described center channel decoding device comprises the first and second decoupling zero devices that respectively the left and right sound channels signal carried out decoupling zero, also comprise the device that is merged into described center channel signal through the left and right sound channels signal of decoupling zero with described, described center channel signal is delivered to described output

Thereby the described decoupling zero device of described center channel decoding device can merge the left and right sound channels signal through the stereophonic signal of power amplification and can not change original left and right sound channels signal.

19. one kind as in claim 18 the center channel decoding circuit of defined, also comprise the device of the amplitude of described center channel signal.

20. the center channel decoding circuit as defined in claim 18, wherein said amplitude control unit comprises at least one variable resistor.

21. the center channel decoding circuit as defined in claim 18, the wherein said first and second decoupling zero devices comprise first and second electric capacity respectively.

22. center channel decoding circuit as defined in claim 21, the wherein said first decoupling zero device comprises first resistance with described first capacitances in series, be connected to described input and receive described left channel signals, and the described second decoupling zero device comprises second resistance with described second capacitances in series, be connected to described input and receive described right-channel signals, described first and second electric capacity are interconnected, and will be merged into described center channel signal through the left channel signals of decoupling zero with through the right-channel signals of decoupling zero.

23. one kind as in claim 22 the center channel decoding circuit of defined, also comprise the device of the amplitude of controlling described center channel signal, and described amplitude control unit comprises at least one variable resistor.

24. the center channel decoding circuit as defined in claim 23, wherein said at least one variable resistor comprises a variable resistor that is configured between described first and second electric capacity interconnection points and the described output.

25. the center channel decoding circuit as defined in claim 23, wherein said at least one variable resistor comprises that (a) is connected on first variable resistor between described first resistance and described first electric capacity; And (b) the second adjustable resistance that is connected between described second resistance and described second electric capacity.

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