JP2001128300A - Digital audio system, its control method, and information recording and reproducing medium with program emulating the digital audio system recorded thereon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a digital audio system of a multi-channel type that can provide a sound field environment with high sound quality. SOLUTION: At least digital attenuators DATL1, DATR1, DATSL1, DATSR1, DATC1, DATSW1 and digital adders ADDL, ADDR, ADDSL, ADDSR are provided in a main transmission path of each channel. The attenuation of the digital attenuators DALT1, DATR1, DATSL1, DATSR1, DATC1, DATSW1 is adjusted depending on types of loudspeakers connected to each channel or combinations of connection/non-connection of the loudspeakers to each channel. Thus, occurrence of overflow can be prevented in advance in the case of applying addition processing of the digital adders ADDL, ADDR, ADDSL, ADDSR to digital audio signals through other digital attenuators DATL2, DATR2, DATSL2, DATSR2, DATC2, DATL4, DATR4, DATSL4, DATSR4 or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio system using digital audio technology, and more particularly, to a digital audio system that processes multi-channel audio signals to reproduce high-quality sound.

[0002]

2. Description of the Related Art With the digitization of information, a digital audio system using digital audio technology has been developed in place of a conventional audio system using analog technology.

In such a conventional digital audio system, although an electric power amplification stage for driving a loudspeaker is left as an analog circuit, most attempts have been made to implement a digital circuit and realize all operations by digital control. Have been.

Attempts have been made to provide a user with a realistic sound field environment of high sound quality by adopting a multi-channel system in which audio is reproduced by a plurality of speakers.

For example, as schematically shown in FIG. 9, main speakers SPL and SPR (front speakers) of two channels on the left and right sides and a center speaker SPC are arranged in front of the user, and two left and right channels behind the user.
The rear speakers (also called surround speakers) SPSL and SPSR of the channels and the subwoofer SPSW are arranged, and the speakers SPL, SPR and SP of the respective channels are arranged.
Attempts have been made to reproduce a realistic sound field environment of high sound quality by supplying an audio signal of a predetermined frequency band for each of SL, SPSR, SPC, and SPSW.

The above digital audio system is provided with a digital signal processing circuit of high channel separation. Each digital signal processing circuit performs digital signal processing for reproducing a realistic sound field environment of high sound quality, converts the digital audio signal subjected to the digital signal processing into an analog audio signal, and converts each of the speakers SPL and SPR. , SPSL, SPSR, SPC, SPS
W is to be driven.

[0007]

By the way, in a multi-channel digital audio system using many such speakers, not only a combination of speakers designated by a manufacturer as an optimum selection but also a user can select a favorite speaker. It is required to do so. In addition, there is a demand for providing a user with a high-quality sound field environment without preparing all speakers for six channels as shown in FIG.

The present invention has been made in view of such a demand, and emulates a digital audio system, a control method thereof, and a digital audio system that enable high-quality sound reproduction even in various combinations of speakers. An object of the present invention is to provide an information recording / reproducing medium on which a program is recorded.

[0009]

In order to achieve the above object, a digital audio system and a control method thereof according to the present invention provide a speaker for each channel based on a plurality of channels of digital audio signals supplied from a signal source. A multi-channel digital audio system to be driven, wherein each of the digital audio signals is transmitted to a speaker of each of the channels, a main transmission path provided for each of the channels, and a main transmission path in each of the main transmission paths. A plurality of digital attenuators provided, to which the respective digital audio signals are supplied; a plurality of digital adders provided in the respective main transmission paths, for inputting outputs of the respective digital attenuators; and the respective digital adders Output to an analog audio signal and A digital-to-analog converter for supplying, when the speaker is not connected to at least one or more main transmission path of the main transmission path of the plurality of channels,
The output of the digital attenuator in the main transmission path to which the speaker is not connected is connected to the digital adder in the main transmission path to which a speaker having a frequency band capable of reproducing the frequency band component of the digital audio signal is connected. A sub-transmission path to be supplied, and a control unit that controls each of the digital attenuators and the sub-transmission path, wherein the control unit includes a speaker on at least one or more main transmission paths of the main transmission paths of the plurality of channels. When not connected, each of the digital attenuators is set to a predetermined attenuation rate, and each of the digital adders in the main transmission path to which the speaker is connected is connected to the output of the digital attenuator from the sub transmission path and to the digital adder. And a digital audio signal of channel No.

According to such a configuration and control method, the attenuation factor of each digital attenuator is set according to various combinations in which a speaker is not connected to each channel.

For example, a multi-channel digital audio system including a left and right two-channel main speaker disposed in front of a user, a left and right two-channel rear speaker disposed behind, a center speaker and a subwoofer. In the case where no subwoofer is provided, the attenuation factor of each digital attenuator is set. Thus, the digital audio signal originally reproduced by the subwoofer is supplied to the digital adder on the main speaker, the rear speaker, and the center speaker, and is reproduced by the main speaker, the rear speaker, and the center speaker.

Here, when the digital adder performs addition processing on a plurality of digital audio signals from channels other than the channel to which the digital adder itself belongs, it is generally assumed that an overflow peculiar to a digital circuit may occur. You.

However, according to the configuration and the control method of the present invention, the occurrence of the overflow is prevented beforehand by appropriately adjusting the attenuation of the digital attenuator provided in the main transmission path of each channel. . By preventing the occurrence of overflow, digital signal processing with a high dynamic range is possible without causing waveform distortion, and it is possible to always provide users with a high-quality sound field environment. To

A speaker having a frequency band narrower than a frequency band component of a digital audio signal supplied from the signal source is connected to at least one or more of the main transmission paths of the plurality of channels. Then, the output of the digital attenuator in the main transmission path to which the speaker of the narrow frequency band is connected is connected to the main transmission connected to a speaker having a frequency band capable of reproducing the frequency band component of the digital audio signal. A sub-transmission path to be supplied to the digital adder in the path; and a control unit for controlling the digital attenuators and the sub-transmission path, wherein the control unit includes at least one of the main transmission paths of the plurality of channels. When the speaker in the narrow frequency band is connected to the main transmission path, each digital attenuator is set to a predetermined Set to the decay rate, the output of the digital attenuator from the sub transmission path and the channel of its own channel are added to the respective digital adders in the main transmission path to which the speaker having the reproducible frequency band is connected. It is characterized by adding a digital audio signal.

According to the configuration and the control method, the attenuation rate of each digital attenuator is set according to various combinations in which a speaker is not connected to each channel.
As a result, by preventing the occurrence of overflow of the digital adder, it is possible to perform digital signal processing in a high dynamic range without causing waveform distortion and to provide a user with a sound field environment of always high sound quality. To provide.

[0016] In the main transmission path of the plurality of channels, the main transmission path to which a speaker having a frequency band narrower than the frequency band component of the digital audio signal supplied from the signal source is connected and the speaker is not connected. When there is a main transmission path, the output of the digital attenuator in the main transmission path to which the speaker in the narrow frequency band is connected and the output of the digital attenuator in the main transmission path to which the speaker is not connected are the digital audio. A sub-transmission path to be supplied to the digital adder in a main transmission path to which a speaker having a frequency band capable of reproducing a frequency band component of a signal is connected, and control for controlling each of the digital attenuators and the sub-transmission path And the control unit is provided from the signal source among the main transmission paths of the plurality of channels. If there is a main transmission path to which a speaker in a frequency band narrower than the frequency band component of the digital audio signal to be connected and a main transmission path to which no speaker is connected exist, each of the digital attenuators is set to a predetermined attenuation rate. At the same time, the digital adder in the main transmission path to which the speaker having the frequency band capable of reproduction is connected, outputs the output of the digital attenuator from the sub transmission path and the digital audio signal of its own channel. It is characterized by adding.

According to this configuration and control method, the attenuation factor of each digital attenuator is set according to various combinations of the type of speaker connected to each channel and the case where no speaker is connected. As a result, by preventing the occurrence of overflow of the digital adder, it is possible to perform digital signal processing in a high dynamic range without causing waveform distortion and to provide a user with a sound field environment of always high sound quality. To provide.

Further, an information recording / reproducing medium on which a program for emulating the digital audio system of the present invention is recorded is a multi-media for driving speakers of each channel based on a plurality of channels of digital audio signals supplied from a signal source. An information recording / reproducing medium recording a program for emulating a channel type digital audio system, wherein a digital audio signal of a channel to which the speaker is not connected unless a speaker is connected to at least one of the plurality of channels. And a digital audio signal of a channel to which a speaker having a frequency band capable of reproducing a frequency band component of a digital audio signal of a channel to which the speaker is not connected is connected at a predetermined attenuation rate and added. First control information for driving a speaker having a frequency band capable of reproducing a frequency band component of the digital audio signal, based on the addition result, and the signal source in at least one of the plurality of channels. When a speaker having a narrower frequency band is connected to the frequency band component of the digital audio signal supplied from the speaker, the digital audio signal of the channel to which the speaker of the narrower frequency band is connected and the speaker of the narrower frequency band are connected. The digital audio signal of the channel to which the speaker having the frequency band component capable of reproducing the frequency band component of the digital audio signal of the connected channel can be reproduced is attenuated at a predetermined attenuation rate and added to the digital audio signal of the connected channel, and based on the addition result , Can reproduce the frequency band component of the digital audio signal First control information for driving a speaker having a frequency band, and a channel to which a speaker having a narrower frequency band than the frequency band component of the digital audio signal supplied from the signal source is connected, among the plurality of channels. When there is a channel to which no speaker is connected, the digital audio signal of the channel to which the speaker having the reproducible frequency band is connected is attenuated at a predetermined attenuation rate,
The attenuated digital audio signal, the digital audio signal of the channel to which the speaker of the narrow frequency band is connected, and the frequency band component of the digital audio signal of the channel to which the speaker is not connected are added, and based on the addition result, Third control information for driving a speaker having a frequency band capable of reproducing the frequency component of the digital audio signal, and a speaker having a frequency band capable of reproducing the frequency band component of the digital audio signal in all the channels Is connected, the fourth control information for driving all speakers is recorded based on the digital audio signal.

According to this information recording / reproducing medium, when the above-mentioned control information is executed by an electronic device such as a personal computer, it becomes possible to emulate the function of a digital audio system constituted by hardware, and , A multi-channel digital audio system can be provided as simple means.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. As an embodiment, a digital control amplifier which is a component of the digital audio system of the present invention will be described. 1 and 2
FIG. 3 is a block diagram illustrating a configuration of a digital control amplifier.

As shown in FIGS. 1 and 2, this digital control amplifier has a signal processing system for six channels for driving six speakers, and a signal processing system for each channel is a digital processing system. It has an analog processing system.

That is, digital audio signals DDL, 6 for six channels supplied from the signal source 1 shown in FIG.
The digital processing system shown in FIGS. 1 and 2 performs digital signal processing on DDR, DDSL, DDSR, DDC, and DDSW, and an analog processing system shown in FIG. Analog audio signals SL, SR, SSL, SSR, SC, SSW
To be supplied to each speaker.

The above-mentioned digital processing system is a digital signal processor (Digital Signal Processor) capable of digitally processing a 24-bit digital audio signal sampled at a sampling frequency of 96 kHz.
ssor: DSP).

In FIG. 1, a signal source 1 is a digital audio device such as a CD player or a DVD player.
6 channels of digital audio signals DDL, DDR, DD reproduced by these digital audio devices
SL, DDSR, DDC, and DDSW are supplied to the digital processing system.

Here, the digital audio signal DDL
Is the left channel main speaker SPL and the digital audio signal DDR is the right channel main speaker SPR and digital audio signal DD shown in FIG.
SL is a left channel rear speaker SPSL, a digital audio signal DDSR is a right channel rear speaker SPSR, a digital audio signal DDC is a center speaker SPC, and a digital audio signal DDSW is a digital audio signal for driving a subwoofer SPSW.

The digital audio signals D
DL, DDR, DDSL, DDSR, DDC, DDSW
Is also 24-bit binary data sampled at a sampling frequency of 96 kHz. For example, this is linear PCM binary data obtained when a DVD player reproduces a DVD recording medium conforming to the DVD audio standard.

A first channel for processing the digital audio signal DDL includes a digital attenuator DATL.
F and a digital adder ADD1 are provided. The second channel for processing the digital audio signal DDR includes a digital attenuator DATRF and a digital adder ADD2.
Is provided. Also, the digital audio signal DD
The digital attenuators DATSLX and DATSLF and the digital audio signal DD are provided on the third channel for processing SL.
The fourth channel for processing SR has digital attenuators DATSRX and DATSRF and digital audio signal DD
The fifth channel for processing C has digital attenuators DATCX and DATCF, and digital audio signal DDSW
A digital attenuator DATSWX and DATSWF are provided in the sixth channel for processing the.

Each of the ten digital attenuators shown in FIG. 1 is formed by a digital multiplier (multiplier). Control data CLF, CRF, CSLX, CSLF, CSRX, CSRF, CCX, CCF, CS
By multiplying WX and CSWF with each other, it exhibits attenuation characteristics.

The control data CLF, CRF, CSLX, CSLF, CS
Although RX, CSRF, CCX, CCF, CSWX, and CSWF are binary data, they are real numbers below the decimal point between -1 and 1 in decimal numbers. This attenuates each input digital audio signal.

The digital adder ADD1 is a 24-bit digital arithmetic unit, and has digital attenuators DATLF and DATSL.
The digital audio signals D1, D3, D5, and D6 output from X, DATCX, and DATSWX are added, and a digital audio signal DL (= D1 + D3 + D5 +
D6) is supplied to the digital attenuator DATL1 shown in FIG.

The digital adder ADD2 is a 24-bit digital arithmetic unit, and has digital attenuators DATRF and DATSR.
The digital audio signals D2, D4, D5, and D6 output from X, DATCX, and DATSWX are added, and the digital audio signal DR (= D2 + D4 + D5 +
D6) is supplied to the digital attenuator DATR1 shown in FIG.

The digital audio signal DSL output from the digital attenuator DATSLF is supplied to the digital attenuator DATSL1 shown in FIG. 2, and the digital audio signal DC output from the digital attenuator DATCF is used as the digital attenuator DATC1 shown in FIG. The digital audio signal DSW output from the digital attenuator DATSWF is the digital attenuator DA shown in FIG.
Each is supplied to TSW1.

Next, in FIG. 2, the first channel includes:
Digital Attenuator DATL1, Digital Attenuator DATL2, Digital Filter (High Pass Filter) HPF
L, digital attenuators DATL3 and DATL4, digital adder ADDL, digital multiplier MPL, D / A converter DACL, analog attenuator AATL, and power amplifier circuit AMPL.

The second channel includes a digital attenuator DATR1, a digital attenuator DATR2, a digital filter (high-pass filter) HPFR, a digital attenuator DATR3 and DATR4, a digital adder ADDR, a digital multiplier MPR, and a D / A converter DACR. , Analog Attenuator AAT
R, a power amplifier circuit AMPR is provided.

The third channel includes a digital attenuator DATSL1, a digital attenuator DATSL2, a digital filter (high-pass filter) HPFSL, a digital attenuator DATSL3 and DATSL4, a digital adder ADDSL, a digital multiplier MPSL, and a D / A converter DACSL. , An analog attenuator AATSL, and a power amplifier circuit AMPSL.

The fourth channel includes a digital attenuator DATSR1, a digital attenuator DATSR2, a digital filter (high-pass filter) HPFSR, a digital attenuator DATSR3 and DATSR4, a digital adder ADDSR, a digital multiplier MPSR, and a D / A converter DACSR. , An analog attenuator AATSR, and a power amplifier circuit AMPSR.

The fifth channel includes, in addition to the digital attenuator DATC1, a digital attenuator DATC2, a digital filter (high-pass filter) HPFC, a digital filter (low-pass filter) LPFC, and a digital attenuator DATC.
3 and DATC4, a digital multiplier MPC, a D / A converter DACC, an analog attenuator AATC, and a power amplifier circuit AMPC.

On the sixth channel, in addition to the digital attenuator DATSW1, a digital attenuator DATSW2, a digital adder ADDSW, a digital filter (low-pass filter) L
PFSW, digital attenuator DATSW3, digital multiplier MP
SW, D / A converter DACSW, analog attenuator AATSW,
A power amplifier circuit AMPSW is provided.

Note that the digital attenuator DATL1, the digital filter HPFL, the digital attenuator DATL3, the digital adder ADDL, and the multiplier M which are the components of the first channel
The transmission path provided with the PL, the D / A converter DACL, the analog attenuator AATL, and the power amplifier AMPL is called a main transmission path. Also, in each of the remaining second to sixth channels, each digital audio signal DR, DS
A path in which the respective components are arranged in series from the input terminals of the L, DSR, DC, and DSW to the output terminals of the analog audio signals SR, SSL, SSR, SC, and SSW is called a main transmission path. I have.

A path that branches from these main transmission paths or joins these main transmission paths is called a sub-transmission path, and these sub-transmission paths are digital attenuators DATL2, DATR2, and DATS.
L2, DATSR2, DATC2, DATR3, DATSL3, DATSR3, DATC3, D
It is composed of ATC4, DATL4, DATR4, DATSL4, DATSR4 and a digital filter LPFC.

Here, each digital attenuator shown in FIG. 2 is formed of a digital multiplier, and each digital attenuator is adapted to input each digital audio signal and each control data CL 1, CL 2 from the control unit 2. ,
CL3, CL4, CR1, CR2, CR3, CR4, CSL1, CSL2, CSL3, CS
L4, CSR1, CSR2, CSR3, CSR4, CC1, CC2, CC3, CC4, CS
By multiplying W1, CSW2, and CSW3 with each other, an attenuation characteristic is exhibited.

The control data CL1, CL2, CL3, CL4, CR
1, CR2, CR3, CR4, CSL1, CSL2, CSL3, CSL4, CSR1, CS
R2, CSR3, CSR4, CC1, CC2, CC3, CC4, CSW1, CSW2, CS
W3 is binary data, but in decimal notation -1
It is a real value after the decimal point between and 1. This attenuates each input digital audio signal.

For convenience of explanation, the control unit 2 is shown in FIGS.
However, in practice, there is only one control unit 2, and the microprocessor controls the entire digital control amplifier.

Digital filters HPFL, HPFR, HPFSL, HPF
As shown in the frequency characteristic diagram of FIG.
It is formed of a second-order high-pass digital filter (that is, a high-pass filter) having a predetermined low-pass cutoff frequency fCL. In addition, each digital filter HPF
L, HPFR, HPFSL, HPFSR, and HPFC can finely adjust the low-frequency cutoff frequency fCL according to the control data CHL, CHR, CHSL, CHSR, and CHC from the control unit 2, and are not shown. When the user operates the remote controller, the control unit 2 controls the control data CHL, CHR, CHSL, CH
The low-frequency cutoff frequency fCL is finely adjusted by SR and CHC. Note that a standard low-frequency cutoff frequency fCL preset at the time of product shipment is 100 Hz as shown in FIG.

The digital filters LPFC and LPFSW are shown in FIG.
As shown in the frequency characteristic diagram of (B), it is formed of a second-order low-pass digital filter (that is, a low-pass filter) having a predetermined high-frequency cutoff frequency fCH. The digital filters LPFC and LPFSW are connected to the control unit 2.
The high-frequency cutoff frequency fCH can be finely adjusted in accordance with the control data CLC and CLSW from the CPU. When a user operates a remote controller (not shown), the control unit 2 controls the high-frequency cut-off frequency fCH according to the control data CLC and CLSW. The cutoff frequency fCH is finely adjusted.
The standard high-frequency cutoff frequency fCH preset at the time of product shipment is 100 Hz as shown in FIG. 3B.

As will be described later with reference to FIGS. 6 to 8,
Digital attenuator DATL2, DATR2, DATSL2, DATSL2,
When DATC2 is cut off, the digital filter LPFSW
Simply becomes conductive. That is, at this time, the input digital audio signal D19 is simply passed as it is as the digital audio signal D25 without performing digital filtering arithmetic processing.

The high-pass filters HPFL, HPFR, HPFS
The operations of L, HPFSR, and HPFC are controlled as follows. That is, the rear speakers SSL and SSR and the center speaker S
If any of C is a “small speaker”, the high-pass filter corresponding to the channel to which the small speaker is connected performs the original digital filtering processing, while the high-pass filter to the channel to which the “large speaker” is connected. The corresponding high-pass filter simply becomes conductive without performing the original digital filtering processing. If all of the rear speakers SSL and SSR and the center speaker SC are “large speakers”, all the high-pass filters HPFL, HPFR, HPFSL, HPFSR, and HPFC
Are simply brought into conduction without performing the original digital filtering processing.

Digital adders ADDSW, ADDL, ADDR, ADDS
L and ADDSR are both 24-bit digital arithmetic units.

Here, the digital adder ADDSW is a digital attenuator DATSW2, DATL2, DATR2, DATSL2, DATSR.
2. Digital audio signal D13 output from DATC2
D18 is added, and the digital audio signal D19 (= D13 + D14 + D15 + D16 + D17 + D1) as the addition result is obtained.
8) to the digital filter LPFSW.

The digital adder ADDL performs an addition operation on the digital audio signals D20, D26, and D27 output from the digital attenuators DATL3, DATC4, and DATL4, and a digital audio signal D31 (= D20 + D26), which is the addition result.
+ D27) to the digital multiplier MPL.

The digital adder ADDR performs an addition operation on the digital audio signals D21, D26 and D28 output from the digital attenuators DATR3, DATC4 and DATR4, and a digital audio signal D32 (= D21 + D26) as the addition result.
+ D28) to the digital multiplier MPR.

The digital adder ADDSL performs an addition operation on the digital audio signals D22 and D29 output from the digital attenuators DATSL3 and DATSL4, and supplies a digital audio signal D33 (= D22 + D29) as the addition result to the digital multiplier MPR. I do.

The digital adder ADDSR performs an addition operation on the digital audio signals D23 and D30 output from the digital attenuators DATSR3 and DATSR4, and supplies a digital audio signal D34 (= D23 + D30) as a result of the addition to the digital multiplier MPR. I do.

The digital multipliers MPL, MPR, MPSL, MPSR are:
Digital audio signals D31, D32, D33, and D34 from the digital adders ADDL, ADDR, ADDSL, and ADDSR, and digital data GDL, GDR, GDSL, and GDSR for volume control from the control unit 2.
Are respectively multiplied (multiplied) to amplify each digital audio signal D31, D32, D33, D34.

Similarly, the digital multipliers MPC and MPSW multiply the digital audio signals D24 and D35 from the digital attenuators DATC3 and DATSW3 by the volume control digital data GDC and GDSW from the control unit 2, respectively. Then, the digital audio signals D24 and D35 are amplified.

When a user operates a volume control button switch provided on a remote controller (not shown) by remote control, the control unit 2 detects an operation amount by the remote control operation and sets a volume corresponding to the operation amount. Digital data GDL, GDR, GDSL, GDSR, GDC, G for setting
It is designed to output DSW.

D / A converters DACL, DACR, DACSL, DACSR,
DACC and DACSW are 24-bit D / A converters, and digital multipliers MPL, MPR, MPSL, MPSR, MPC, MPS
Digital audio signals D36 and D3 output from W
7, D38, D39, D40 and D41 are analog audio signals (hereinafter referred to as analog audio signals) S, respectively.
1, S2, S3, S4, S5, and S6 are converted and output.

Analog Attenuator AATL, AATR, AATS
L, AATSR, AATC, AATSW are D / A converter DACL, DACR, D
Each of the analog audio signals S1, S2, S3, S4, S5, and S6 output from ACSL, DACSR, DACC, and DACSW is controlled by the control unit 2.
Digital data GAL, GAR, GASL,
Each of the amplified analog audio signals S11, S21, S31, S41, S51, and S61 is amplified according to GASR, GAC, and GASW, and the corresponding power amplifier circuits AMPL and AM of the corresponding channel.
Supply to PR, AMPSL, AMPSR, AMPC, AMPSW.

The analog attenuators AATL, AATR, AA
TSL, AATSR, AATC and AATSW are all formed by analog circuits shown in the circuit diagram of FIG.

That is, the digital data GA for volume control
Switching elements Q0 to Q23 for 24 bits corresponding to the respective binary bits b0 to b23 of L, GAR, GASL, GASR, GAC, and GASW, and a plurality of switching elements Q0 to Q23 cascaded in a ladder-like manner. Load resistance R0-R2
3 and r0 to r23. The analog audio signals S1, S2, S3, S4, S5, and S6 are supplied to the load resistor r23 on the uppermost switching element Q23 side.

According to this configuration, the switching elements Q0 to Q23 are turned on or off according to the logical values of the binary bits b0 to b23 of the digital data GAL, GAR, GASL, GASR, GAC, and GASW from the control unit 2. Will be controlled,
Each analog audio signal S1, S2, S3, S4, S5,
S6 is divided by the load resistances R0 to R23 and r0 to r23. That is, load resistances R0 to R23 and r0 to r
Digital data GAL, GAR, GASL, GA
By controlling by SR, GAC, and GASW, a desired attenuation rate can be obtained.

The digital multipliers MPL, MPR, MPSL, MPS
R, MPC, MPSW and analog attenuator AATL, AATR, AATS
L, AATSR, AATC, and AATSW are controlled in conjunction with each other.

That is, as shown in the characteristic diagram of FIG. 5, the user operates the volume control button switch provided on the remote controller to change the value from 0 (dB) to +16.
When instructing to set the amplification factor within the range of (dB), the control unit 2 sets the analog attenuators AATL and AAT
The amplification factors of R, AATSL, AATSR, AATC, and AATSW are fixed to 0 (dB), and the control unit 2 controls the digital multipliers MPL, MPR, MPSL,
Controls the amplification rate of MPSR, MPC and MPSW.

The user operates the volume control button switch provided on the remote controller to set the amplification factor (attenuation factor) within the range of 0 (dB) to -90 (dB). If the instruction is given to
Is a digital multiplier MPL, MPR, MPSL, MPSR, MPC, MPSW
Of the analog attenuators AATL, AATR, AATSL, AATSR, AATC, and AATSW are controlled in accordance with the operation amount of the volume control button switch. .

When the user instructs the amplification factor 0 (dB) by the volume control button switch provided on the remote controller, the control unit 2 sets the digital multipliers MPL, MPR, MPSL, MPSR , MPC, MPSW and analog attenuator AATL, AATR, AATSL, AATSR, AATC, AATS
The amplification rate (attenuation rate) of W is set to 0 (dB).

Further, the control unit 2 has a digital amplifier for automatically setting the optimum volume according to the type of the speaker connected to the power amplifier circuits AMPL, AMPR, AMPSL, AMPSR, AMPC, and AMPSW of each channel. Data GDL, GDR, GDSL, GDSR,
GDC, GDSW, GAL, GAR, GASL, GASR, GAC, GASW are generated and output. Also, if no speaker is connected to a predetermined channel out of the six channels, or if there is a speaker that is connected but set not to operate, the speaker that is connected to the remaining channels is Digital data GDL, GDR, GDSL, GDSR, GDC, GDS for sounding at optimum volume
W, GAL, GAR, GASL, GASR, GAC, GASW are generated and output.

Power amplifier circuits AMPL, AMPR, AMPSL, AMPSR,
AMPC and AMPSW are both formed by analog power amplifier circuits with excellent linearity and wide frequency band, and analog attenuators AATL, AATR, AATSL, AATSR, AATC,
Each analog audio signal S11, S21, S3 from AATSW
1, S41, S51, S61 are power-amplified, and the power-amplified analog audio signals SL, SR, SSL, SS
R, SC, and SSW are assigned to speakers SPL and S of each channel.
The data is supplied to PR, SPSL, SPSR, SPC, and SPSW.

Although not shown, each power amplifier circuit AM
The output terminals of PL, AMPR, AMPSL, AMPSR, AMPC, and AMPSW are connected to the speakers SPL, SPR, SPSL, and SPS, respectively.
A plurality of connectors for detachably connecting R, SPC, and SPSW are provided, and a user can connect a desired speaker through these connectors.

Next, the operation of the digital control amplifier having the above configuration will be described with reference to FIGS. 6, 7 and 8.

FIGS. 6 to 8 show that the user can use the six speakers SPL, SPR, SPSL, SPSR, SP
When C and SPSW are arbitrarily selected and connected,
FIG. 3 shows a specific attenuation rate of each digital attenuator shown in FIGS. 1 and 2. Also, six speakers SPL,
An arbitrary combination of SPR, SPSL, SPSR, SPC, and SPSW is indicated as “mode 1” to “mode 22”.

For example, “mode 1” shown in FIG.
Speakers SPL, SPR, SPSL, S for channels
This figure shows a case where all of PSR, SPC, and SPSW are loudspeakers of a type called “large loudspeaker”. That is, the description of “large” in the figure means “large speaker”. "Yes" for subwoofer SPSW
Shows the case where the subwoofer SPSW is connected.

Further, these speakers SPL, SPR,
Numerical values described in the lower column following the upper column showing combinations of SPSL, SPSR, SPC, and SPSW are specific attenuation rates of the respective digital attenuators controlled by the control unit 2 in FIGS. is there.

The unit of the attenuation rate is decibel (dB), and the digital attenuator set to 0 (dB) is
This means that the input digital audio signal is output without being attenuated. Also, -∞ (d
The digital attenuator set to B) means that the input digital audio signal is completely cut off. That is, it means that the digital audio signal is not propagated to the output side.

Further, the description of “none” shown in the subwoofer SPSW column in “mode 2” or the like indicates that the user is not connected when the subwoofer SPSW is connected, or even when the subwoofer SPSW is connected. This means that a setting instruction is given to the control unit 2 so as not to sound the subwoofer SPSW.

Further, the combination of “present” and “absent” can be selected for the rear speakers SPSL, SPSR and the center speaker SPC.

The description of “small” shown in “mode 3”, “mode 4” and the like means that a type of speaker called “small speaker” is connected.

Here, the above “large speaker” is
A loudspeaker having a flat frequency characteristic in a wide frequency band from a low frequency to a high frequency. Generally, it means a so-called high-end model speaker.

On the other hand, a "small speaker" is a speaker whose sound reproducibility in a low frequency band (frequency band of 100 Hz or less) is inferior to that of a "large speaker", and is generally a relatively low price. Refers to speakers.
The subwoofer SPSW is a speaker that has reproducibility of heavy bass in a frequency band of 100 Hz or less.

Next, these "mode 1" to "mode 2"
2 ”,“ Mode 1 ”,“ Mode 9 ”,“ Mode 1 ”
The operation in the case of "0" will be described as a representative example.

In the case of “mode 1”, as described above,
The user has all speakers SPL, SPR, SPSL,
This is a case where SPSR, SPC, and SPSW are connected to the digital control amplifier, and these speakers are “large speakers”.

Then, the user operates the above-mentioned remote controller, and the large speakers SPL, SPR, S
When the control unit 2 is instructed to connect the PSL, SPSR, SPC, and SPSW, the control unit 2 automatically sets the attenuation factor of each digital attenuator.

In the "mode 1", the digital attenuators DATLF, DATRF, DATSLF, DATSRF, and DATC shown in FIG.
The attenuation factors of F and DATCF are set to 0 (dB), and the attenuation factors of the digital attenuators DATSLX, DATSRX, DATCX, and DATSWX are set to -∞ (dB).

As a result, the digital audio signals D3, D5 and D6 are not substantially supplied to the digital adder ADD1. Further, digital audio signals D4, D5 and D6 are not substantially supplied to the digital adder ADD1. The digital adders ADD1 and ADD2 convert the digital audio signals D1 and D2 into digital audio signals DL and D, respectively.
R is the digital attenuator DATL1, DATR1 in FIG.
To supply.

Further, digital attenuators DATLF, DATR
F, DATSLF, DATSRF, DATCF, DATCF attenuation rate is also 0 (d
B), the digital audio signals DDL, DDR, DDSL, DDSR, DDC, DDSW from the signal source 1 are set.
Are digital audio signals DL, DR, DSL, DS
2. Digital attenuators DATL1, DATR1, DATSL1, DATSR1, DATC1, and DAT in FIG.
Supplied to SW1.

That is, in the “mode 1”, the circuit shown in FIG. 1 simply outputs the digital audio signals DDL, DDR, DDS
A process for transferring only L, DDSR, DDC, and DDSW to the circuit shown in FIG. 2 is performed.

Next, the digital attenuator DATL shown in FIG.
1, DATR1, DATSL1, DATSR1, DATC1, DATSW1, DATSW2, D
The attenuation rates of ATL3, DATR3, DATSL3, DATSR3, DATC3, and DATSW3 are set to 0 (dB). Furthermore, digital attenuators DATC2, DATL2, DATSR2, DATSL2, DATSR2, DATC4, D
The attenuation rate of ATL4, DATR4, DATSL4, and DATSR4 is -∞ (d
B) is set.

That is, the digital attenuators DATL1, DAT
R1, DATSL1, DATSR1, DATC1, DATSW1, DATSW2, DATL3,
DATR3, DATSL3, DATSR3, DATC3, and DATSW3 are simply turned on, and the digital attenuators DATC2, DATL2, and DATS
R2, DATSL2, DATSR2, DATC4, DATL4, DATR4, DATSL4, D
ATSR4 enters the cutoff state.

As a result, the digital audio signals D14, D15, D16, D17 and D18 are no longer supplied to the digital adder ADDSW. Therefore, the digital audio signal DSW of the sixth channel is supplied to the digital multiplier MPSW as the digital audio signal D35.

Further, the digital adders ADDL, ADDR, ADDS
Digital attenuators DATL3, DTL
Digital audio signal D from ATR3, DATSL3, DATSR3
20, D21, D22, and D23 are supplied, respectively. For this reason, the digital audio signals DL, DR, DSL, and DSR of the first to fourth channels are respectively supplied to digital filters HPFL, HPFR, HPFSL, and HPFSR as they are to remove the frequency components of 100 Hz or less, and the digital audio signal D31 , D32, D33 and D34 are supplied to digital multipliers MPL, MPR, MPSL and MPSR.

Further, also in the fifth channel, the digital audio signal DC is supplied as it is to the digital filter HPFC to remove the frequency component of 100 Hz or less, and is supplied to the digital multiplier MPC as the digital audio signal D24.

Further, the control unit 2 controls the digital multipliers MPL and M
PR, MPSL, MPSR, MPC, MPSW and analog attenuator ATT
The amplification factor in each of the channels L, ATTR, ATTSL, ATTSR, ATTC, and ATTSW is set to 0 (dB). That is, the total gain of the digital multiplier MPL and the analog attenuator ATTL is set to 0 (dB), and the total gain of the combination of the digital multiplier and the analog attenuator of another channel is also set to 0 (dB). Therefore, the digital audio data D31, D of each channel
32, D33, D34, D24, and D35 are not amplified or attenuated, and are analog audio signals SL, SR,
It is converted into SSL, SSR, SC, SSW, and each speaker SPL, SPR, SPSL, SPSR, SPC, SP
It is supplied to SW.

As described above, in the case of the “mode 1”, the digital audio signals DDL, DDR, DDSL, DDSR, DDSR,
The DDC and DDSW are converted into analog audio signals SL, SR, SSL, SSR, SC, and SSW substantially as they are, and the respective speakers SPL, SPR, SPSL, and SPS are converted.
Supply to R, SPC and SPSW.

Next, the operation in the case of "mode 9" will be described. In this case, the user sets the main speakers SPL, SPL
PR is “Large speaker”, rear speaker SPSL, S
This is a case where the PSR and the center speaker SPC are “small speakers”. In this case, a subwoofer SPSW is connected.

In the "mode 9", the digital attenuators DATLF, DATRF, DATSLF, DATSRF, and DATC shown in FIG.
The attenuation factors of F and DATCF are set to 0 (dB), and the attenuation factors of the digital attenuators DATSLX, DATSRX, DATCX, and DATSWX are set to -∞ (dB).

As a result, in the “mode 9”, the circuit shown in FIG. 1 simply outputs the digital audio signals DDL, DDR, DDS
A process for transferring only L, DDSR, DDC, and DDSW to the circuit shown in FIG. 2 is performed.

Next, the digital attenuator DATL shown in FIG.
1, the attenuation rates of DATR1, DATSL1, DATSR1, DATC1, and DATSW1 are set to -20 (dB). Furthermore, digital attenuators DATSW2, DATC2, DATSL2, DATSR2, DATL3, DATR
3, the attenuation rate of DATSL3, DATSR3, DATC3, and DATSW3 is 0 (d
B) is set. Furthermore, digital attenuator DA
The attenuation rates of TL2, DATR2, DATC4, DATL4, DATR4, DATSL4, and DATSR4 are set to -∞ (dB).

When the attenuation rate of each attenuator in FIG. 2 is set as described above, the digital attenuators DATL2 and DATR
2, DATC4, DATL4, DATR4, DATSL4, and DATSR4 are cut off, and the digital attenuators DATSW2, DATC2, DATSL2, D
ATSR2, DATL3, DATR3, DATSL3, DATSR3, DATC3, DATSW3
Becomes conductive.

Further, digital attenuators DATL1 and DATR
1, digital audio signals D8, D9, D10, D11, D12, D output from DATSL1, DATSR1, DATC1, and DATSW2
13 are digital audio signals DL, DR, D, respectively.
SL, DSR, DC, and DSW are signals attenuated by -20 (dB).

As a result, the digital audio signals DSL, DSR, DC, and DSW are each supplied to the digital adder ADDSW after being attenuated by -20 (dB). The digital audio signals DSL, DSR, DC, and DSW attenuated by -20 (dB) are added, and only the frequency band component of 100 Hz or less is separated by the digital filter LPFSW, and the digital multiplier MP of the sixth channel is added.
Supplied to SW.

Further, the digital multiplier MP of the fifth channel
To C, only a frequency band component of 100 Hz or more of the digital audio signal DC attenuated by -20 (dB) is supplied after being separated.

Further, the digital adder ADDL of the first channel has only the digital audio signal D20, the digital adder ADDR of the second channel has only the digital audio signal D21, and the digital adder ADDSL of the third channel has the digital audio signal ADDSL. Only the signal D22 is supplied to the digital adder ADDSR of the fourth channel by the digital audio signal D23.
Only each is supplied.

Therefore, the digital multiplier MPLL of the first channel is provided with 10 out of the digital audio signal DL.
Only the frequency band component of 0 Hz or more is separated and supplied, and only the frequency band component of 100 Hz or more of the digital audio signal DR is separated and supplied to the digital multiplier MPR of the second channel. Digital audio signal DSL is input to digital multiplier MPSL.
Of the digital audio signal DSR, only the frequency band component of 100 Hz or higher is separated and supplied to the digital multiplier MPSR of the fourth channel.

Further, the control unit 2 controls the digital multipliers MPL and M
PR, MPSL, MPSR, MPC, MPSW and analog attenuator ATT
The amplification factor in each channel of L, ATTR, ATTSL, ATTSR, ATTC, and ATTSW is set to 20 (dB). That is, the total gain of the digital multiplier MPL and the analog attenuator ATTL is set to 20 (dB), and the total gain of the combination of the digital multiplier and the analog attenuator of another channel is also set to 20 (dB).

Therefore, in the case of the "mode 9", the digital audio signals DDL and DDR supplied from the signal source 1 are substantially applied to the main speakers SPL and SPR which are the large speakers of the first and second channels. Are supplied as they are after being directly converted into analog audio signals SL and SR. Each of the digital audio signals DDS is provided to rear speakers SPSL and SPSR, which are small speakers of the third, fourth, and fifth channels, and a center speaker SPC.
L, DDSR, DDC are digital filters HPFSL, HPFSR, HP
The frequency band components of 100 Hz or less are removed by the FC, converted into analog audio signals SSL and SSR, and supplied.

On the other hand, the digital audio signals DDSL and DDSR are added to the digital audio signal DDSW, and the added digital audio signal is converted into an analog audio signal SSW and supplied to the sixth channel subwoofer SPSW. .

That is, the rear speakers SPSL, SPS
When R is a small speaker, the sound reproducibility of the rear speakers SPSL and SPSR in a frequency band of 100 Hz or less is reduced. Therefore, to compensate for the reduced sound reproducibility, the digital audio signals DD of the third and fourth channels are used.
SL and DDSR are added to the digital audio signal DDSW, and the added digital audio signal is converted to an analog audio signal SSW and supplied to the subwoofer SPSW. That is, the subwoofer SPSW is 100
Since the sound reproducibility in the low frequency band below Hz is excellent,
By supplying the low frequency band component of the digital audio signals DDSL and DDSR that are not reproduced by the rear speakers SPSL and SPSR to the subwoofer SPSW, it is possible to provide a user with a high-quality sound field environment.

Next, the operation in the case of "mode 10" will be described. The “mode 10” is a case where the user sets the main speakers SPL and SPR to “large speaker”, sets the rear speakers SPSL and SPSR and the center speaker SPC to “small speaker”, and does not connect or sound the subwoofer SPSW.

In this “mode 10”, the digital attenuators DATLF, DATRF, DATSLF, DATSRF, DA shown in FIG.
The attenuation rate of the TCF is set to -4.65 (dB), and the attenuation rate of the digital attenuator DATSWX is set to -7.65 (dB).
B) is set to digital attenuator DATSLX, DATSR
The attenuation rates of X, DATCX, and DATSWF are set to -∞ (dB).

As a result, the digital attenuator DATSWF is cut off, so that the digital audio signal DDSW is not supplied to the sixth channel.

Since the subwoofer SPSW is not connected or does not sound, the digital adder ADD1 adds the digital audio signal DDSW to be supplied to the subwoofer SPSW to the digital audio signal DDL, and It is supplied to the main speaker SPL which is a speaker. Also, the digital adder ADD2 is
The digital audio signal DDSW to be supplied to the subwoofer SPSW is added to the digital audio signal DDR and supplied to the main speaker SPR which is a large speaker.

In the third, fourth, and fifth channels, digital audio signals DSL, DSR, and DC are generated by attenuating the digital audio signals DDSL, DDSR, and DDC by -4.65 (dB) each. Is done.

As described above, in the "mode 10", the circuit shown in FIG. 1 performs a process for supplying the digital audio signal DDSW, which should be originally supplied to the subwoofer SPSW, to the speaker of another channel.

Next, the digital attenuator DATL shown in FIG.
1, the attenuation rates of DATR1, DATSL1, DATSR1, DATC1, and DATSW1 are set to -15.4 (dB). Furthermore, digital attenuators DATSW2, DATC2, DATL2, DATR2, DATSL4, D
The ATSR4 and DATSW3 attenuation factors are set to -∞ (dB). In addition, digital attenuators DATSL2, DATSR2, DATL
3, the attenuation rate of DATR3, DATSL3, DATSR3, and DATC3 is 0 (d
B) is set. Furthermore, digital attenuator DATC
4, the attenuation rates of DATL4 and DATR4 are set to -4.5 (dB).

Further, the control unit 2 controls the digital multipliers MPL and M
PR, MPSL, MPSR, MPC, MPSW and analog attenuator ATT
The amplification factor in each channel of L, ATTR, ATTSL, ATTSR, ATTC, and ATTSW is set to 20 (dB). That is, the total gain of the digital multiplier MPL and the analog attenuator ATTL is set to 20 (dB), and the total gain of the combination of the digital multiplier and the analog attenuator of another channel is also set to 20 (dB).

As a result, the digital attenuators DATSW2,
Since DATC2, DATL2, DATR2, DATSL4, DATSR4, and DATSW3 are in the cutoff state, the digital adder ADDSW adds the digital audio signals D16 and D17, and outputs the added digital audio signal D19 (= D16 + D17) to the digital filter LPFSW. Supply. And the digital filter LPFSW
Supplies only the low frequency band component of 100 Hz or less of the digital audio signal D19 (= D16 + D17) to the digital adders ADDL and ADDR of the first and second channels via the digital attenuators DATL4 and DATR4.

The digital filter LPCF applies only the components of the digital audio signal D12 in the frequency band lower than 100 Hz to the digital adders ADDL and ADDR of the first and second channels via the digital attenuator DATC4.
To supply.

Therefore, the digital adder ADDL of the first channel outputs the digital audio signal D2 shown in FIG.
0, D26 and D25 are added and supplied to the digital multiplier MPL. The second channel digital adder ADDR adds the digital audio signals D21, D26, and D28 shown in FIG. 2 and supplies the result to the digital multiplier MPR.

That is, in the case of “mode 10”, the rear speakers SPSL and SPSR are small speakers having low sound reproducibility in a low frequency band of 100 Hz or less. For this reason, the low frequency band components of the digital audio signals DSL and DSR are converted into digital signals of the first and second channels through a path including the digital attenuators DATSL2 and DATSR2, the digital adder ADDSW, the digital filter LPFSW and the digital attenuators DATL4 and DATR4. The signals are supplied to the adders ADDL and ADDR, and are reproduced by the main speakers SPL and SPR.

The center speaker SPC is also 100H.
Since the speaker is a small speaker having low sound reproducibility in a low frequency band equal to or lower than z, the low frequency band component of the digital audio signal DC is converted to the first and second channels via a digital filter LPF and a digital attenuator DATC4. , And are reproduced by the main speakers SPL and SPR. Further, as described above, the digital audio signal DDSW to be supplied to the subwoofer SPSW is added in advance to the digital audio signal DDL and DDR by the circuit shown in FIG.
Digital audio signal DDSW is also the main speaker SP
L, SPR.

Note that the rear speakers SPSL and SPSR and the center speaker SPC substantially correspond to digital data DDS.
L, DDSR and DDC are reproduced as they are.

As described above, in the case of “mode 10”,
The heavy bass that should be reproduced by the subwoofer SPSW,
The low-frequency band sound that is not reproduced by the rear speakers SPSL and SPSR and the center speaker SPC is reproduced by the main speakers SPL and SPR, thereby providing a high-quality sound field environment for the user.

In modes other than "mode 1", "mode 9" and "mode 10" described above, the user can automatically adjust the attenuation rate of each digital attenuator in accordance with the combination of the loudspeakers. It is possible to provide a high-quality sound field environment.

Next, the effect of the present digital control amplifier will be described.

As shown in FIGS. 1 and 2, the present digital control amplifier has a
The attenuation factors of the plurality of digital attenuators are controlled according to various combinations with the case where no speaker is connected, thereby providing a user with a high-quality sound field environment.

Here, the digital attenuator DA shown in FIG.
By providing TL1, DATR1, DATSL1, DATSR1, DATC1, and DATSW1 respectively in the main transmission path of each channel, it is possible to reproduce high-quality sound without causing waveform distortion.

That is, as in the case of "mode 10",
If no speaker is connected to a particular channel,
When a “small speaker” is to be connected, as described above, a digital audio signal of a low frequency band component to be reproduced by the “large speaker” originally connected to those channels is transmitted to another speaker. (A speaker with good low-frequency sound reproducibility). The addition process is performed by the digital adders ADDL, ADDR, ADDSL, ADDSR, and ADDSW shown in FIG.

Thus, the digital adders ADDL, ADDR, AD
If the DSL, ADDSR, and ADDSW perform addition processing on a plurality of digital audio signals from channels other than the channel to which the DSL, ADDSR, and ADDSW belong, there is a possibility that an overflow unique to a digital circuit may occur.

The digital adders ADDL, ADDR, ADDSL, A
If an overflow occurs in the DDSR and ADDSW, harsh sounds will be reproduced, making it difficult to provide a high-quality sound field environment. Further, there is a problem that an analog audio signal having an excessive amplitude is supplied to a speaker.

However, in the present embodiment, as described above, the digital attenuators DATL1, DATR1, DATSL1, and DATS1,
R1, DATC1, and DATSW1 are provided in the main transmission path of each channel, and digital adders ADDL, ADDR, ADDS
When L, ADDSR, and ADDSW also add a plurality of digital audio signals from channels other than the channel to which they belong, the control unit 2 controls these digital attenuators.
By appropriately controlling the attenuation rate of DATL1, DATR1, DATSL1, DATSR1, DATC1, and DATSW1, the occurrence of an overflow peculiar to digital circuits is prevented beforehand.

As described above, the occurrence of an overflow is prevented beforehand by such a configuration, thereby enabling digital signal processing in a high dynamic range. As a result, excellent functions obtained by digital signal processing can be maximized.

Also, by adopting the circuit configuration shown in FIGS. 1 and 2, the digital attenuators DATL1, DATR1, DATSL
By optimally controlling each attenuation factor, including not only 1, DATSR1, DATC1, and DATSW1, but also the remaining digital attenuators, it is possible to always provide users with a high-quality sound field environment.

The embodiment of the digital audio system (particularly, digital control amplifier) constituted by so-called hardware has been described. However, the present invention is not limited to this. The configuration shown in FIGS. 1 and 2 is realized by a computer program, and the computer program is executed by an electronic device (for example, a personal computer or the like) incorporating a microprocessor. By executing the digital audio system, a multi-channel digital audio system equivalent to the case of hardware may be realized.

The computer program described above is
As an application file for realizing a multi-channel digital audio system, DVD (Di-
gital Video Disk or Digital Versatile Disk) or the like, and the application file is installed or downloaded to an electronic device such as the personal computer capable of reproducing the information recording / reproducing medium. You may make it perform.

As described above, the functions of the hardware shown in FIGS. 1 and 2 can be emulated by recording the information file on the information recording / reproducing medium as an application file composed of a computer program, and reproducing and executing it. Thus, a multi-channel digital audio system can be provided to the user as a simple means.

[0135]

As described above, according to the present invention, a digital attenuator and a digital adder are provided in the main transmission path of each channel, and the types of speakers connected to each channel or the speakers for each channel are provided. When adding digital audio signals from other channels to the digital adder according to the combination of connection and non-connection, the attenuation rate of the digital attenuator in the main transmission path is adjusted appropriately, so that digital addition It is possible to prevent the occurrence of overflow in the vessel.

Therefore, it is possible to perform digital signal processing in a high dynamic range without causing waveform distortion and to always provide a user with a sound field environment of high sound quality.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a digital control amplifier according to an embodiment.

FIG. 2 is a block diagram further illustrating the configuration of the digital control amplifier according to the embodiment;

FIG. 3 is a diagram showing a frequency characteristic of a digital filter built in a digital control amplifier.

FIG. 4 is a circuit diagram showing a configuration of an analog attenuator built in the digital control amplifier.

FIG. 5 is a diagram illustrating gain characteristics of a digital multiplier incorporated in a digital control amplifier.

FIG. 6 is a diagram illustrating an attenuation rate of a digital attenuator controlled according to a connection mode of a speaker.

FIG. 7 is a diagram further illustrating an attenuation factor of a digital attenuator controlled according to a connection mode of a speaker.

FIG. 8 is a diagram further illustrating an attenuation rate of a digital attenuator controlled according to a connection mode of a speaker.

FIG. 9 is a schematic diagram showing a general speaker arrangement in a multi-speaker system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Signal source 2 ... Control part SPL, SPR ... Main speaker SPSL, SPSR ... Rear speaker SPC ... Center speaker SPSW ... Subwoofer DATL1, DATR1, DATSL1, DATSR1, DATC1, DATSW1 ... Digital attenuator DATL2, DATR2, DATSL2, DATSR2, DATC2 , DATSW2 ... Digital attenuator DATL3, DATR3, DATSL3, DATSR3, DATC3, DATC4, DATSW3
… Digital attenuator DATL4, DATR4, DATSL4, DATSR4, DATC4… Digital attenuator ADDSW, ADDL, ADDR, ADDSL, ADDSR… Digital adder HPFL, HPFR, HPFSL, HPFSR, HPFC… Digital filter (high-pass filter) LFC, LPFSW… Digital filter (Low-pass filter)

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Kazuya Kinoshita 4-2610 Hanazono, Tokorozawa, Saitama Prefecture Pioneer Corporation Inside the Tokorozawa Plant (72) Sadako Hibino 4-2610 Hanazono, Tokorozawa-shi, Saitama Pioneer Shares Inside the Tokorozawa Plant (72) Inventor Akihisa Yamaguchi 4-2610 Hanazono, Tokorozawa City, Saitama Prefecture Inside Tokorozawa Plant, Pioneer Corporation (72) Inventor Ikuko Kawamura 4-2610 Hanazono, Tokorozawa City, Saitama Prefecture Inside Tokorozawa Plant, Pioneer Corporation F term (reference) 5J023 AA09 AB02 AC06 AD11

Claims (6)

[Claims] 1. A multi-channel digital audio system for driving a speaker of each channel based on a digital audio signal of a plurality of channels supplied from a signal source. A main transmission path provided for each channel for transmitting to the speaker side; a plurality of digital attenuators provided in each of the main transmission paths and supplied with each of the digital audio signals; and each of the main transmission paths A plurality of digital adders each provided therein and receiving an output of each of the digital attenuators; a digital-to-analog converter that converts an output of each of the digital adders into an analog audio signal and supplies the analog audio signal to each of the speakers; At least one of the main transmission paths of the plurality of channels
If a speaker is not connected to the main transmission path, the output of the digital attenuator in the main transmission path to which the speaker is not connected is connected to a speaker having a frequency band capable of reproducing a frequency band component of the digital audio signal. A sub-transmission path to be supplied to the digital adder in the main transmission path, and a control unit that controls each of the digital attenuators and the sub-transmission path, wherein the control unit is a main transmission path of the plurality of channels. When a speaker is not connected to at least one of the main transmission paths, each of the digital attenuators is set to a predetermined attenuation rate, and each of the digital adders in the main transmission path to which the speakers are connected is The output of the digital attenuator from the sub-transmission path and the digital audio signal of its own channel Digital Audio System for causing added. 2. A multi-channel digital audio system for driving a speaker of each channel based on a digital audio signal of a plurality of channels supplied from a signal source. A main transmission path provided for each channel for transmitting to the speaker side; a plurality of digital attenuators provided in each of the main transmission paths and supplied with each of the digital audio signals; and each of the main transmission paths A plurality of digital adders each provided therein and receiving an output of each of the digital attenuators; a digital-to-analog converter that converts an output of each of the digital adders into an analog audio signal and supplies the analog audio signal to each of the speakers; At least one of the main transmission paths of the plurality of channels
When a speaker having a frequency band narrower than the frequency band component of the digital audio signal supplied from the signal source is connected to the main transmission path, the main transmission path to which the speaker having the narrow frequency band is connected is connected. A sub-transmission path for supplying the output of the digital attenuator to the digital adder in a main transmission path to which a speaker having a frequency band capable of reproducing a frequency band component of the digital audio signal is connected; A control unit that controls a digital attenuator and the sub-transmission line, wherein the control unit is configured to connect the speaker of the narrow frequency band to at least one or more main transmission paths of the main transmission paths of the plurality of channels. , A speaker having a frequency band in which the digital attenuator is set to a predetermined attenuation rate and the reproduction is possible. Digital Audio System, characterized in that said respective digital adders in the main transmission path connected, thereby adding the digital audio signal output and self channel of the digital attenuator from the sub-transmission path. 3. A multi-channel digital audio system for driving a speaker of each channel based on a digital audio signal of a plurality of channels supplied from a signal source, wherein the digital audio signal is converted to a digital signal of each channel. A main transmission path provided for each channel for transmitting to the speaker side; a plurality of digital attenuators provided in each of the main transmission paths and supplied with each of the digital audio signals; and each of the main transmission paths A plurality of digital adders each provided therein and receiving an output of each of the digital attenuators; a digital-to-analog converter that converts an output of each of the digital adders into an analog audio signal and supplies the analog audio signal to each of the speakers; Of the main transmission paths of a plurality of channels, When there is a main transmission path to which a speaker in a narrow frequency band is connected and a main transmission path to which no speaker is connected compared to the frequency band component of the supplied digital audio signal, the speaker in the narrow frequency band is connected. The output of the digital attenuator in the main transmission path and the output of the digital attenuator in the main transmission path to which no speaker is connected are connected to a speaker having a frequency band capable of reproducing a frequency band component of the digital audio signal. A sub-transmission path to be supplied to the digital adder in the main transmission path, and a control unit that controls each of the digital attenuators and the sub-transmission path, wherein the control unit is a main transmission path of the plurality of channels. A frequency band narrower than a frequency band component of the digital audio signal supplied from the signal source. When there is a main transmission path to which the speaker is connected and a main transmission path to which the speaker is not connected, each of the digital attenuators is set to a predetermined attenuation rate, and a speaker having a frequency band capable of reproducing is connected. A digital audio system, wherein the digital adder in the main transmission path adds an output of the digital attenuator from the sub transmission path and a digital audio signal of its own channel. 4. The control section, when a speaker having a frequency band capable of reproducing a frequency band component of the digital audio signal is connected to all of the main transmission paths, adjusts an attenuation rate of each of the digital attenuators. The digital audio system according to any one of claims 1 to 3, wherein the digital audio system is set to 0 and the sub-transmission path is cut off. 5. A control method of a multi-channel digital audio system for driving a speaker of each channel based on a digital audio signal of a plurality of channels supplied from a signal source, wherein: If a speaker is not connected to one or more channels, a speaker having a frequency band capable of reproducing the frequency band components of the digital audio signal of the channel to which the speaker is not connected and the digital audio signal of the channel to which the speaker is not connected is connected. Attenuating the digital audio signal of the channel at a predetermined attenuation rate and adding the same, and based on the addition result, driving a speaker having a frequency band capable of reproducing the frequency band component of the digital audio signal, of When a speaker having a frequency band narrower than a frequency band component of the digital audio signal supplied from the signal source is connected to at least one or more channels, the digital audio of the channel to which the speaker having the narrow frequency band is connected is connected. Attenuating a signal and a digital audio signal of a channel connected to a speaker having a frequency band capable of reproducing a frequency band component of the digital audio signal of the channel connected to the speaker of the narrow frequency band at a predetermined attenuation rate. And driving a speaker having a frequency band capable of reproducing a frequency band component of the digital audio signal based on a result of the addition, of the plurality of channels, a frequency of the digital audio signal supplied from the signal source. Speech in frequency band narrower than band component If there is a channel to which a speaker is connected and a channel to which no speaker is connected, the digital audio signal of the channel to which the speaker having the reproducible frequency band is connected is attenuated at a predetermined attenuation rate, and the attenuated digital signal is attenuated. An audio signal, a digital audio signal of a channel to which the narrow frequency band speaker is connected, and a frequency band component of a digital audio signal of a channel to which the speaker is not connected are added, and based on the addition result, the digital audio signal is When a speaker having a frequency band capable of reproducing the frequency band component of the digital audio signal is connected to all the channels, a speaker having a frequency band capable of reproducing the frequency component of the digital audio signal is connected to the digital audio signal. On the basis of, A method for controlling a digital audio system, comprising driving all speakers. 6. An information recording / reproducing medium in which a program for emulating a multi-channel digital audio system for driving a speaker of each channel based on a plurality of channels of digital audio signals supplied from a signal source is recorded. If a speaker is not connected to at least one of the plurality of channels, a digital audio signal of a channel to which the speaker is not connected and a frequency band component of a digital audio signal of a channel to which the speaker is not connected can be reproduced. A digital audio signal of a channel to which a speaker having a frequency band is connected is attenuated at a predetermined attenuation rate and added, and based on the addition result, a frequency band in which a frequency band component of the digital audio signal can be reproduced is determined. First control information for driving a loudspeaker, and a loudspeaker having a frequency band narrower than a frequency band component of a digital audio signal supplied from the signal source is connected to at least one of the plurality of channels. And a speaker having a frequency band capable of reproducing the frequency band components of the digital audio signal of the channel to which the narrow frequency band speaker is connected and the digital audio signal of the channel to which the narrow frequency band speaker is connected. Attenuating the digital audio signal of the digital audio signal at a predetermined attenuation rate and adding the resultant signal, and based on the addition result, driving a speaker having a frequency band capable of reproducing a frequency band component of the digital audio signal. Control information; and from the signal source among the plurality of channels. If there is a channel to which a speaker having a frequency band narrower than the frequency band component of the supplied digital audio signal is connected and a channel to which no speaker is connected, a channel to which a speaker having a reproducible frequency band is connected Of the digital audio signal of the channel to which the speaker of the narrow frequency band is connected and the frequency of the digital audio signal of the channel to which the speaker is not connected. Third control information for driving a speaker having a frequency band capable of reproducing the frequency component of the digital audio signal based on the addition result, and the digital audio signal for all the channels. Frequency band And a fourth control information for driving all the speakers based on the digital audio signal is recorded when a speaker having a frequency band capable of reproducing is connected. An information recording / reproducing medium on which a program to be emulated is recorded.