JPH04102395U - Digital channel divider for speakers - Google Patents

Abstract

(57) [Summary] [Purpose] By flattening the overall sound pressure frequency characteristics and linearizing the phase frequency characteristics of each channel, it is possible to reproduce faithful audio signals, and to further improve the performance of each speaker unit in the low frequency range. An object of the present invention is to provide a digital channel divider for speakers that can prevent excessive input to the speaker. [Structure] The digital channel divider of this invention connects multiple filters in parallel that can arbitrarily set desired transmission frequency characteristics for digital input signals, and outputs the signals output from each filter independently. The structure includes an inverse filter for characteristic correction that flattens the overall sound pressure frequency characteristic of each channel and linearizes the phase frequency characteristic, and limits excessive input applied to the speaker unit below the lowest resonance frequency of the speaker unit. A digital high-pass filter is provided on one or more channels.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention is a digital channel used in multi-amplifier speaker systems. This relates to channel dividers.

0002

[Conventional technology]

Conventionally, for example, multi-channel speakers that use a combination of multiple speakers dedicated to frequency bands have been used. In a way-type speaker system, the structure consists of a coil and a capacitor. The method using the LC network that is created and the method for each frequency band (channel) A multi-amplifier system using a dedicated channel divider is adopted. LCne Channel dividers used in networks and multi-amplifier systems operate in the audio frequency range. The frequency range is divided into several necessary frequency bands, and a speaker dedicated to the corresponding frequency band is created. It has the function of supplying an acoustic signal to the car.

0003 By the way, in the multi-amplifier system, the channel divider, which is composed of an electronic circuit, Digitalization has been progressing. Figure 5 shows, for example, the channel disclosed in Jitsuhei 2-6673. This is an example of a channel divider that uses the above-mentioned multi-amplifier method using a digital method. This is a block diagram showing an example of a speaker system. In the figure 2, 2₁ ,2₂ ,...2_n is a plurality of power amplifiers, 3,3₁ ,3₂ ,...3_n is multiple Several speaker units, 4 is a channel divider (frequency band division circuit) , a plurality of linear phase FIR type filters 4₁ ,4₂ ,...4_n It consists of 4 ₁₁ ,4_{twenty two},...4_nnare the desired frequency bands for the above linear phase FIR type filter, respectively. Multiple filters are used as a calculation means to provide filter coefficients to provide zone division characteristics. router coefficient variable device, 5,5₁ ,5₂ ,...5_n are multiple D/A conversion circuits .

0004 In the above multi-way speaker system, the digital signal input is is applied to the channel divider 4, and the linear phase FIR type filter 4₁ ,4₂ ,...4_n and a filter coefficient variable device 4 for providing desired frequency band division characteristics.₁₁,4 _{twenty two} ,...4_nnA convolution operation is performed with the filter coefficients. Next, linear phase FIR shape filter 4, 4₁ ,4₂ ,...4_n The output of each D/A converter 5, 5₁ ,5₂ ,...5_n It is converted into an analog signal by the power amplifier 2, 2.₁ ， 2₂ ,...2_n is amplified to a predetermined level by speaker units 3, 3.₁ ,3 ₂ ,...3_n is converted into sound.

[0005]

[Problem that the idea aims to solve]

The multi-way speaker system described above uses linear phase FIR type filters 4 ₁ , 4 ₂ , ... 4 _n as the channel divider 4, so although the linear phase characteristics are maintained in the channel divider section, the speaker unit Generally, the sound pressure frequency characteristics of the waveform do not have a linear phase, so the finally obtained sound pressure frequency characteristics cannot always have a linear phase. As a result, the waveform of the reproduced sound is distorted, making it difficult to reproduce the sound faithfully.

[0006] This invention was made to solve the above problems, and each channel In order to achieve flattening of the overall sound pressure frequency characteristics and linearization of the phase frequency characteristics of This makes it possible to reproduce the acoustic signal faithfully, and further improves the accuracy of each speaker unit in the low frequency range. Provides a digital channel divider for speakers that prevents excessive input to the The purpose is to

[0007]

[Means to solve the problem]

In the digital channel divider for speakers according to the present invention, each channel Characteristic correction that flattens the overall sound pressure frequency characteristics and linearizes the phase frequency characteristics. Input level applied to the positive inverse filter and speaker unit in the low frequency range A digital high-pass filter is provided on one or more channels to limit the

[0008]

[Effect]

In the digital channel divider according to the present invention, the total sound pressure frequency of each channel is An inverse filter for characteristic correction that flattens the wave number characteristic and linearizes the phase frequency characteristic. and a digital high-pass filter that limits input in the low frequency range. While achieving faithful reproduction of acoustic signals, excessive input is applied to the speaker unit. prevent this from happening.

[0009]

【Example】

FIG. 1 is a block diagram showing an embodiment in which a digital channel divider according to the present invention is used in a multi-amp speaker system. In FIG. 1, symbols 2 _{, 2 1} , 2 ₂ , ... 2 _n are power amplifiers, 3, _{3 1} , 3 ₂ , ... 3 _n are speaker units, 10 is a digital channel divider according to the present invention, 4, 4 ₁ , 4 ₂ ,... _4n are frequency band division circuits that are components of the digital channel divider 10, and _6,61,62 ,... _6n are speaker units 3, ₃₁ , _{32 ,} ...3 in the low frequency range. A digital high-pass filter 7 limits the input to _n , and 7 is a component of the digital channel divider 10, which performs characteristic correction to flatten the amplitude characteristic and linearize the phase frequency characteristic of the overall transmission frequency characteristic of each channel. 7 ₁ , 7 ₂ , ... 7 _n is a characteristic correction FIR filter that is a component of the characteristic correction inverse filter 7 , 7 ₁₁ , 7 ₂₂ , ... 7 _nn is an inverse filter coefficient generation circuit, 5 , 5 ₁ , 5 ₂ , . . . 5 _n are D/A conversion circuits for converting digital signals into analog signals, and 20 is a microphone for measuring sound pressure frequency characteristics.

0010 The operation will be explained with reference to FIG. The digital input signal is first divided into frequency bands. You will be guided to path 4. The frequency band division circuit 4 uses an FIR filter and an IIR filter. The signal is divided into desired frequency bands by digital filters such as .

[0011] The output signal from the frequency band division circuit 4 is then passed through a digital high-pass filter 6. input level at a frequency below the speaker unit's lowest resonant frequency. reduced. The reason for using the digital high-pass filter 6 will be described later.

The digital output signal whose input is restricted below the lowest resonance frequency by the digital high-pass filter 6 is then input to the characteristic correction inverse filter 7 . In the characteristic correction inverse filter 7, the correction FIR filters 7 _{1 ,} 7 _{2 ,} . A real-time convolution operation is performed with the coefficient data of 7 ₂₂ , . . . 7 _nn to produce a digital signal whose characteristics have been corrected.

[0013] In this way, the digital data whose characteristics have been corrected in advance by the characteristic correction inverse filter 7 The signal is further processed by D/A conversion circuits 5, 5.₁ ,5₂ ,...5_n converted to an analog signal by , power amplifier 2, 2₁ ,2₂ ,...2_n via the speaker units 3, 3 ₁ ,3₂ ,...3_n guided by. Speaker unit 3, 3₁ ,3₂ ,...3_n Well then , the characteristic-corrected analog signal and the impulse response of the speaker unit sound pressure. Convolution is performed, and the final result is a flattening of the sound pressure frequency characteristic and a straight line of the phase frequency characteristic. Realize the

In FIG _. 1, the coefficient data of the inverse filter coefficient _generation circuits _{7 11} , 7 ₂₂ , _. The system from which the coefficient data to be given or the digital signal is input until it finally reaches the microphone 20 (sound wave propagation time t ₁ , t 2 from the speaker units 3, 3 ₁ , 3 ₂ , ... 3 _n to the microphone ₂₀ ) , . . . t _n ) are set to coefficient data that gives an inverse characteristic of the overall transmission frequency characteristic excluding the digital high-pass filter 6 and characteristic correction inverse filter 7.

[0015] The reason for this is the frequency characteristics of the analog signal whose characteristics have been corrected in advance and the frequency characteristics of the speaker. - The sound pressure frequency characteristics of the unit compensate each other, and at least the sound pressure frequency characteristics of the speaker unit Achieves flat sound pressure and phase straightness above the lowest resonant frequency of the cutter, ensuring faithful transmission of acoustic signals. This is to realize transmission and playback.

[0016] Figure 2 shows the electro-acoustic characteristics of a typical speaker unit. and electrical impedance 33. Shown in Figure 2 As shown in the sound pressure frequency characteristic 31, the sound pressure level generally decreases in the low frequency range. did Therefore, the frequency characteristic 32 of the characteristic correction inverse filter 7 is necessarily in the low frequency range. This results in an increased sound pressure level. As a result, an inverse filter 7 for characteristic correction is provided. When this happens, the input voltage to the speaker unit increases rapidly in the low frequency range, and the This will result in damage to the peaker unit.

[0017] The purpose of introducing the digital high-pass filter 6 is to reduce the speed in the low frequency range as mentioned above. This is to limit excessive input to the peaker unit. Especially digital high pass By selecting the cutoff frequency of filter 6 near the lowest resonance number of the speaker unit, Since the input level in the low frequency range drops rapidly, it is difficult to overload the speaker unit. It becomes possible to suppress input efficiently.

[0018] As mentioned above, the digital high-pass filter 6 and characteristic correction inverse filter 7 are By providing it as a component of the digital channel divider 10, the sound Faithful reproduction of acoustic signals and prevention of excessive input can be achieved at the same time.

[0019] In addition, the arrangement order of the frequency band division circuit 4 and the characteristic correction inverse filter 7 is changed. Of course, the above operation is the same in both cases.

[0020] Example 2. Figure 3 shows the digital channel divider according to the present invention used in a multi-amplifier system. Another embodiment used in a car system is shown in a block diagram.

[0021] The basic operation in Fig. 3 is the same as in Fig. 1, and for the same reason, the fidelity of the acoustic signal is Reproduction and prevention of excessive input can be achieved at the same time.

[0022] The difference from Fig. 1 is that the digital high-pass filter 6 and the characteristic correction inverse filter 7 are used. This is because a high-pass/characteristic correction filter 67 that integrates the above is provided.

[0023] Here, integration has the following meaning. That is, the digital high-pass filter 6 is realized by an FIR type filter, and the filter coefficient data is convolved with the coefficient data of the coefficient generation circuits 7 ₁₁ , 7 ₂₂ , . . . 7 _nn that give the inverse characteristics of the speaker unit in advance. , the calculation result is used as new coefficient data to construct an FIR type digital filter.

In FIG. 3, 67 ₁ , 67 ₂ , ... 67 _n are high-pass/characteristic correction FIR type filters provided for the above purpose, and 67 ₁₁ , 67 ₂₂ , ..., 67 _nn are the results of the convolution operation. This is a coefficient generation circuit for a high-pass/characteristic correction filter having new coefficient data.

[0025] Example 3. Figure 4 shows the digital channel divider according to the present invention used in a multi-amplifier system. This is a block diagram showing a third embodiment used in a car system.

[0026] The basic operation in Fig. 4 is the same as in Figs. 1 and 3, and for the same reason, the acoustic signal faithful reproduction and prevention of excessive input can be achieved at the same time.

[0027] The difference from Figures 1 and 3 is the frequency band division circuit 4 and digital high-pass filter. Frequency band division/high pass/characteristics integrated with 6 and characteristic correction inverse filter 7 This is because a correction filter 467 is provided.

[0028] Here, integration has the same meaning as in the second embodiment. That is, the frequency band dividing circuit 4 and the digital high-pass filter 6 are realized by FIR type filters, and the coefficients of these filters are subjected to a convolution operation in advance, and the coefficient generation circuit ₇₁₁ provides the result of the operation and the inverse characteristic of the speaker unit. , 7 ₂₂ , . . . 7 _nn , and the finally obtained calculation result is used as new coefficient data to construct an FIR type digital filter.

In FIG. 4, 467 ₁ , 467 ₂ , ..., 467 _n are frequency band division/high pass/characteristic correction FIR type filters provided for the above purpose, and 467 ₁₁ , 467 ₂₂ , ..., 467 _nn are convolution filters. This is a coefficient generation circuit for a frequency band division/high pass/characteristic correction filter having new coefficient data obtained as a result of calculation.

[0030]

[Effect of the idea]

As mentioned above, the digital channel divider of this invention has a Inverse characteristic correction for flattening the overall sound pressure frequency characteristic and linearizing the phase frequency characteristic filter and digital high-pass filter to reduce input below the lowest resonant frequency. Since the filter is installed, it is possible to achieve faithful reproduction of the acoustic signal and at the same time prevent excessive input from being caused by the speaker. This has the effect of preventing the car from joining the car unit.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment of this invention.

FIG. 2 is a block diagram showing a second embodiment of the invention.

FIG. 3 is a characteristic diagram showing the electroacoustic characteristics of a general speaker unit in terms of sound pressure frequency characteristics and electrical impedance.

FIG. 4 is a block diagram showing a third embodiment of the invention.

FIG. 5 is a block diagram showing a conventional example of a multi-amplifier speaker system using a digital method.

[Explanation of symbols]

2 _{, 2} 1 , 2 ₂ , ... 2 _n Power amplifier 3, _{3 1} , 3 ₂ , ... 3 _n Speaker unit 4 Frequency band division circuit 4 ₁ , 4 ₂ , ... 4 _n Linear phase FIR type filter 5, 5 ₁ , 5 ₂ ,...5 _n D/A conversion circuit 6, 6 ₁ , 6 ₂ ,..., 6 _n Digital high-pass filter 7 Inverse filter for characteristic correction 71 , 7 ₂ ,...7 _i ...7 _n FIR type filter 711 for characteristic correction , 7 ₂₂ ,...7 _ii ...7 _nn Coefficient generation circuit for inverse filter 10 Digital channel divider 20 Microphone 67 High pass/characteristic correction filter 67 ₁ , 67 ₂ ,..., 67 _n FIR type filter for high pass/characteristic correction 67 ₁₁ , 67 ₂₂ ,...,67 _nn High pass/characteristic correction filter coefficient generation circuit 467 Frequency band division/high pass/characteristic correction filter 467 ₁ ,467 ₂ ,...,467 _n Frequency band division/high pass/characteristic correction FIR type filter 467 ₁₁ ,467 ₂₂ ,...,467 _nn Frequency band division/high pass/characteristic correction filter coefficient generation circuit t ₁ , t ₂ ,...t _n Sound wave propagation time from speaker unit to microphone

Claims (7)

[Scope of utility model registration request] Claim 1: A digital channel for a speaker configured to connect a plurality of filters in parallel so that desired transmission frequency characteristics can be arbitrarily set for a digital input signal, and to output signals output from each filter independently. The divider includes one or more digital high-pass filters whose cutoff frequency approximately matches the lowest resonant frequency of the speaker unit, as well as an inverse filter that provides the inverse characteristics of the sound pressure frequency characteristics of the speaker unit connected to each channel. A digital channel divider for speakers characterized by being provided in the channel. [Claim 2] A digital channel for a speaker configured to connect a plurality of filters in parallel so that desired transmission frequency characteristics can be arbitrarily set for a digital input signal, and to output signals output from each filter independently. A divider that provides an inverse characteristic of the overall transmission frequency characteristic excluding the digital high-pass filter and the inverse filter for correcting the sound pressure characteristics of the speaker unit for the system from which the digital signal is input until it finally reaches the microphone 20. A digital channel divider for a speaker, characterized in that a digital high-pass filter whose cutoff frequency substantially matches the lowest resonant frequency of a speaker unit is provided in one or more channels together with a filter. [Claim 3] A digital channel for a speaker configured to connect a plurality of filters in parallel so that desired transmission frequency characteristics can be arbitrarily set for a digital input signal, and to output signals output from each filter independently. The divider is a digital high-pass filter provided in one or more channels to remove the DC input applied to the speaker unit, as well as an inverse filter that provides an inverse characteristic of the sound pressure frequency characteristic of the speaker unit connected to each channel. A digital channel divider for speakers characterized by: 4. A digital channel for a speaker configured to connect a plurality of filters in parallel so that desired transmission frequency characteristics can be arbitrarily set for a digital input signal, and to output signals output from each filter independently. The divider is an inverse filter that provides the inverse characteristics of the overall transmission frequency characteristic, excluding the digital high-pass filter and the inverse filter for correcting the sound pressure characteristics of the speaker unit, for the system from which the digital signal is input until it finally reaches the microphone. A digital channel divider for a speaker, characterized in that the digital high-pass filter for removing DC input applied to the speaker unit is provided in one or more channels. 5. The digital channel divider for speakers according to claim 1, wherein an FIR type digital filter is used as the digital high-pass filter and the inverse filter. 6. An FIR-type filter that integrates the digital high-pass filter and the inverse filter by convolving the coefficient data of the FIR-type digital filter set as the digital high-pass filter and the inverse filter is provided in one or more channels. The digital channel divider for speakers according to claim 1, 2, 3, or 4, characterized in that: 7. A frequency band dividing circuit, a digital high-pass filter, and an inverse filter are set as an FIR digital filter, and the frequency band dividing circuit, digital high-pass filter, and inverse filter are set by convolving the coefficient data of the set FIR type digital filter. Claims 1, 2, and 3, characterized in that one or more channels are provided with an FIR type filter that integrates
4. The digital channel divider for speakers according to item 4.