JPH048718Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to the improvement of a sound field reproducing device such as a four-channel stereo reproducing device.

[Prior Art] A conventional simple 4-channel playback device will be explained with reference to FIG. 6.
are left and right channel input terminals, respectively, 02L
and 02R are amplifier circuits connected to the left and right channel input terminals, 03L and 03R, respectively.
04 are front speaker devices connected to the amplifier circuits 02L and 02R, respectively;
L and 04R are rear speaker devices in which respective same-polarity (-terminal) input terminals are connected to each other, and the other input terminal (+ terminal) is connected to amplifier circuits 02L and 02R.

With this configuration, the left channel input signal is E _L ,
When the right channel input signal is E _R , signals A, E L, A, and E _R are applied to the front speaker devices 03L and 03R, respectively, and independent left and right signals are reproduced, and the rear speaker devices 03L and 03R receive signals A, E _L , A, and E R respectively. A _{signal A(EL-ER )} /2 is applied to the speaker device 04L, and a signal A( _ER - _EL )/2 is applied to the rear speaker device 04R, so that the left and right difference signals are reproduced.

[Problems to be solved by the invention] In the above conventional example, we focused on the fact that the reverberation component that creates the atmosphere of a hall, etc. is included as an antiphase component in the recorded signal, and we installed left and right speakers in the rear speaker device. It attempts to reproduce reverberation components by applying a difference signal.

However, in the case of stereo recording, sounds in the mid-high range have short wavelengths, so phase and level differences between the left and right microphones tend to occur, resulting in a large level difference between the left and right signals, but sounds in the low range have long wavelengths. Therefore, since the phase level difference between the left and right microphones is small, the level difference between the left and right signals becomes small, resulting in an unsatisfactory reproduction of low-frequency reverberant sound.

Furthermore, especially in small audio playback devices, a two-way speaker system consisting of a low-output amplifier of about 10W to 40W and at most a speaker for bass reproduction and a speaker for treble reproduction is often used due to installation space and cost considerations. Since the internal volume of the box is inevitably small and it is difficult to use a large diameter speaker, there is also dissatisfaction with the bass reproduction ability of the front speaker device.

Generally, as a means to improve the bass reproduction ability under the above conditions, in order to lower the lowest resonant frequency of the bass reproduction speaker, the mass of the vibration system of the speaker is increased.
On the other hand, there is a problem in that the efficiency of the bass reproduction speaker is reduced, and in order to obtain a balance for the speaker device as a whole, it is necessary to limit the input of the medium and high frequency speakers, resulting in a reduction in the efficiency of the speaker device as a whole.

On the other hand, in a small audio reproduction device, as mentioned above, there is a conflicting factor in that since the output of the amplifier is limited, it is advantageous for the efficiency of the speaker device to be as high as possible.

As a means to solve this problem, it has been adopted to add a so-called low boost circuit or tone control circuit to the amplifier, which increases the degree of amplification of only the bass signal.

However, in a small audio playback device in which the output of the amplifier is limited as described above in an amplifier equipped with this type of circuit, the signal will be clipped even when the input level is lower by the amount of boost.

Therefore, when a bass signal and a treble signal are mixed, the treble signal is cross-modulated by the bass signal,
This may cause deterioration in sound quality.

Further, even in the case of only a bass signal, there is a problem in that due to the generation of harmonics due to clipping, the harmonic components are reproduced from the high-frequency speaker, causing deterioration in sound quality.

[Means for Solving the Problems] This invention was devised in view of the problems of the above-mentioned conventional example. a first amplifier circuit, a low-pass filter circuit connected to the left channel signal input terminal, a subtraction circuit whose inputs are the left channel signal input terminal and the low-pass filter circuit output terminal, and the subtraction circuit output terminal. a second amplifier circuit connected to the first amplifier circuit; a first output terminal connected to the first amplifier circuit output terminal; a second output terminal connected to the second amplifier circuit output terminal; and a second output terminal connected to the right channel signal input terminal. a third amplifier circuit, a low-pass filter circuit connected to the right channel signal input terminal, a subtraction circuit whose inputs are the right channel signal input terminal and the low-pass filter circuit output terminal, and an output of the subtraction circuit. a fourth amplifier circuit connected to the output terminal of the third amplifier circuit; and a third amplifier circuit connected to the third amplifier circuit output terminal.
an amplifier having an output terminal and a fourth output terminal connected to the output terminal of the fourth amplifier circuit; a left front speaker device having at least a bass reproduction speaker and a treble reproduction speaker; and at least a bass reproduction speaker and a treble reproduction speaker. A rear left speaker device having a reproduction speaker, a right front speaker device having at least a bass reproduction speaker and a treble reproduction speaker, and a right rear speaker device having at least a bass reproduction speaker and a treble reproduction speaker. The positive end of the treble reproduction speaker of the left front speaker device is connected to the first output terminal and the negative end is connected to the ground, and the positive end of the bass reproduction speaker of the left front speaker device is connected to the first output terminal. a first output terminal, a negative end connected to the second output terminal, a positive end of a treble reproduction speaker of the right front speaker device connected to the third output terminal, and a negative end connected to ground; The positive end of the bass reproduction speaker of the right front speaker device is connected to the third output terminal, and the negative end is connected to the fourth output terminal.
the positive end of the high frequency reproduction speaker of the left rear speaker device is connected to the first output terminal, and the negative end of the high frequency reproduction speaker of the right rear speaker device is connected to the negative terminal of the high frequency reproduction speaker of the right rear speaker device. , the positive end of the bass reproduction speaker of the left rear speaker device is connected to the first output terminal, and the negative end of the bass reproduction speaker of the right rear speaker device is connected to the second output terminal; is connected to the third output terminal, its negative terminal is connected to the negative terminal of the treble reproduction speaker of the left rear speaker device, and the positive end of the bass reproduction speaker of the right rear speaker device is connected to the third output terminal. and a negative terminal thereof is connected to the fourth output terminal, respectively.

[Function] With the above-mentioned configuration, this invention allows the treble reproduction speaker of the rear-placed speaker device to output left and right difference signals as in the conventional example, and the bass reproduction speaker to output left and right difference signals with only the low range enhanced. The left and right signals are transmitted independently, and the treble reproduction speakers of the front-mounted speaker device transmit the left and right signals independently.
The bass reproduction speaker reproduces the left and right signals independently, with only the low frequencies enhanced, thus solving the problems of the conventional system.

[Example] In FIG. 1, 1L and 1R are the left channel signal input terminal and right channel signal input terminal, respectively, and 21L and 21R are the input terminals 1 and 21R, respectively.
The first and third amplifier circuits 5L and 5R connected to L and 1R respectively are filter circuits connected to the left channel signal input terminal 1L and right channel signal input terminal 1R, respectively, and 6L and 6R are respectively connected to the output signal of the filter circuit 5L. and a subtraction circuit that obtains a difference signal between the left channel signal input terminal 1L signal and a filter circuit 5R output signal and the right channel signal input terminal 1R signal, respectively;
22L and 22R are the subtraction circuits 6L and 22R, respectively.
2nd and 4th amplifier circuits connected to 6R, 41L,
42L, 41R, 42R are the first, second,
first, second, third and fourth output terminals connected to the third and fourth amplifier circuits, 42'L, 4;
2'R is a fifth terminal connected to the second output terminal 42L and the variable resistor 9L, and the fourth output terminal 42R and the variable resistor 9R, respectively.
and a sixth output terminal, 7L and 7R are left and right front speaker devices, respectively, 8L and 8R are left and right rear speaker devices, respectively, and each speaker device 7L, 7R, 8L, 8R
is at least the high frequency reproduction speakers 71L, 71
R, 81L, 81R and bass reproduction speaker 72
It is composed of L, 72R, 82L, and 82R.

And the high frequency reproduction speakers 71L and 8
The positive end of each of 1L is connected to the first output terminal 41L.
Then, the positive ends of the high-frequency sound reproduction speakers 71R and 81R are respectively connected to the third output terminal 41R. The high frequency reproduction speakers 71L and 7
Each negative terminal of 1R is connected to ground. The negative terminals of the high-frequency sound reproducing speakers 81L and 81R are connected to each other, and the connection point is connected to ground via a variable resistor 10. On the other hand, the positive end of the bass reproduction speaker 72L is connected to the first output terminal 41L, and the negative end is connected to the second output terminal 42L.
The positive end of the terminal is connected to the third output terminal 41R, and the negative end is connected to the fourth output terminal 41R.
Each is connected to the output terminal 42R. Also, the positive end of the bass reproduction speaker 82L is connected to the first output terminal 41L, the negative end is connected to the fifth output terminal 42'L, and the positive end of the bass reproduction speaker 82R is connected to the third output terminal 41R, and the negative end is connected to the third output terminal 41R. The extreme ends are respectively connected to the sixth output terminal 42'R.

In the above configuration, filter circuits 5L, 5R
The transfer function of T, the amplifier circuits 21L, 22L, 21
If the gains of R and 22R are A, and the signals input to the input terminals 1L and 1R are E _L and E _R , then the signal vL1 applied to the first output terminal 41L, the second output terminal 42L (the fifth output terminal 42 'L: signal vL2 applied to the variable resistor's resistance value 9L as 0), signal vR1 applied to the third output terminal 41R, fourth output terminal 42R (sixth output terminal 42'R: variable resistor 9
The signal vR2 applied to the terminals (assuming the resistance value of R is 0) is vL1=A・E _L vL2=A(1−T)E _L vR1=A・E _R vR2=A(1−T)E _R Therefore, the treble reproduction speaker 71L has A・E _L , the treble reproduction speaker 71R has A・E _R , and the treble reproduction speaker 81L has A.
(E _L − E _R )/2, A ( _ER − E _L )/2 for the high frequency reproduction speaker 81R, and the bass reproduction speaker 72.
Signals A, T, and E _L are input to L and 82L, respectively, and signals A, T, and E _R are input to bass reproduction speakers 72R and 82R, respectively.

Here, if T is a low pass filter or a low band pass filter having a gain of 1 or more (for example, 2), the bass reproduction speaker 72
L, 82L, 72R, and 82R are respectively applied with a low frequency signal that is twice the level of the high frequency reproduction speakers 71L and 71R, which reduces the efficiency of the low frequency reproduction speakers by that much, thereby reducing the lowest resonance. It is possible to lower the frequency and improve low frequency reproduction ability.

The filter circuit used in the sound field reproducing device of the present invention has a falling characteristic of 6 dB/oct expressed by a transfer function of T=2/1+jω/ω2, as shown in Figure 2-a. Low-pass filter circuit, a low-pass filter with rise and fall characteristics of 6 dB/oct expressed by the transfer function of T=2jω/ω1/(1+jω/ω1)(1+jω/ω2), as shown in Figure 2-b. Circuit, 2nd-c
A low-pass filter circuit with a falling characteristic of 12 dB/oct expressed by the transfer function of T=2/1+2ζ ₂ jω/ω2 + (jω/ω2) ² , with the characteristics shown in Figure 2-d. As such, T=2jω/ω1/(1+jω/ω1) {1
+2ζ2+{jω/ω2) ² } rise characteristic of 6dB/oct expressed by the transfer function,
A bandpass filter circuit with a falling characteristic of 12 dB/oct, as shown in Figure 2-e, T=2(jω/ω1) ² /1+2ζ ₂ jω/ω
1+(jω/ω1) 12dB/oct increase characteristic expressed by the transfer function of ²・1/1+jω/ω2,
A bandpass filter circuit with a falling characteristic of 6 dB/oct, as shown in Figure 2-f, T=2(jω/ω1) ² /1+2ζ ₁ jω/ω
1+(jω/ω1) ²・1/1+2ζ ₂ jω/ω2+(jω/ω2
) A bandpass filter circuit or the like having a 12 dB/oct rise and fall characteristic expressed by a transfer function of ² can be used.

FIG. 3 shows one channel (left channel) of an amplifier using a bandpass filter that provides the characteristics shown in FIG. 2-e.

In addition, by changing ζ1 or ζ1 and ω1 simultaneously in the filter circuit with the characteristics shown in Figure 2-e and Figure 2-f, the low resonant frequency of the speaker system can be adjusted as shown in Figures 4-a and 4-b. It was possible to control the level of the lower frequency band by lowering the frequency band, or by increasing the level of the frequency band slightly lower than the low resonance frequency.

Figures 5-a and 5-b are examples in which a variable gain filter circuit is applied to obtain the above effect, and ζ is shown in Figure 5-a, and ζ and ω are shown in Figure 5-b.
can be varied at the same time.

Also, by adjusting the variable resistors 9L and 9R, the low frequency level of the rear speaker systems 8L and 8R can be adjusted, and by adjusting the variable resistor 10, the distribution of high frequency left and right signals of the rear speaker system can be adjusted. Each can be adjusted.

[Effects of the invention] Therefore, according to this invention, even though the reverberation time is long, the low-frequency signal components with few out-of-phase components are reproduced in the same band as the front bass reproduction speakers, so the reproduction level is lower. is significantly increased compared to the conventional example, and it is possible to overcome the lack of low frequency reproduction of rear speakers.

In addition, if necessary, a variable resistor can be added, and by adjusting this, the front and rear level balance of the low frequency signal and the left and right mixing ratio of the rear high frequency reproduction sound can be varied, thereby adjusting the acoustic characteristics of the signal source and reproduction space. It can be set to the optimum state depending on the situation.

Furthermore, in order to improve the low frequency reproduction ability, even if a speaker system designed to lower the low frequency resonant frequency by increasing the mass of the vibration system is connected, the input level of the bass reproduction speaker may be changed to the high frequency. Compared to that of the speaker,
Since the speaker system can be made larger in size, the bass reproduction ability can be improved without compromising the overall balance of the speaker system.

Also, unlike conventional low-boost circuits, in this design, only one amplifier circuit performs the low-boost effect, and the amplifier circuit connected to the treble speaker has flat characteristics. Even if the frequency of the high-frequency sound is increased, it will not have any effect on the other amplifier circuit, and the characteristics of the high-frequency sound reproduction speaker will not deteriorate due to the frequency characteristics of the low-frequency sound reproduction speaker, so deterioration of the sound quality of the high-frequency sound reproduction can be prevented. It has the following advantages.

Although a two-way speaker device has been described as an example of a speaker device for front and rear placement, if necessary, a multi-way speaker device with other low-frequency speakers attached via an appropriate network circuit can be used as a speaker device for high-frequency sound reproduction. Of course, a way type speaker device can also be applied.

[Brief explanation of the drawing]

Figure 1 is a block circuit diagram of an embodiment of this invention, Figures 2-a to 2-f are characteristic diagrams of a low-pass filter circuit used in this invention, and Figure 3 is a block circuit diagram of an embodiment of this invention.
- A filter circuit diagram that provides the characteristics shown in figure e,
Figures 4-a and 4-b are frequency characteristic diagrams of this invention using a variable gain filter circuit, Figures 5-a and 5-b are diagrams of a variable gain filter circuit, respectively. The figure is a block circuit diagram of a conventional sound field reproduction device. 1L and 1R are input terminals, 21L and 2
2L, 21R and 22R are amplifier circuits, 4
1L, 42L, 41R and 42R are output terminals, 5L and 5R are filter circuits, 6L and 6R are subtraction circuits, respectively, 7L and 7R are front speaker systems, 8L and 8R, respectively.
are respectively rear-placed speaker systems.

Claims (1)

[Claims for Utility Model Registration] A first amplifier circuit 21L connected to the left channel signal input terminal 1L, the right channel signal input terminal 1R, and the left channel signal input terminal 1L.
and a low-pass filter circuit 5L connected to the left channel signal input terminal 1L, and a subtraction circuit 6 whose inputs are the left channel signal input terminal 1L and the output terminal of the low-pass filter circuit 5L.
L and the second connected to the output terminal of the subtraction circuit 6L.
an amplifier circuit 22L, a first output terminal 41L connected to the output terminal of the first amplifier circuit 21L, a second output terminal 42L connected to the output terminal of the second amplifier circuit 22L, and the right channel signal input terminal 1.
a third amplifier circuit 21R connected to R, a low pass filter circuit 5R connected to the right channel signal input terminal 1R, the right channel signal input terminal 1R and the low pass filter circuit 5.
a subtraction circuit 6R whose input is the R output terminal; and a fourth amplifier circuit 2 connected to the output terminal of the subtraction circuit 6R.
2R, a third output terminal 41R connected to the output terminal of the third amplifier circuit 21R, and the fourth amplifier circuit 2.
An amplifier 11 having a fourth output terminal 42R connected to the 2R output terminal, and at least a bass reproduction speaker 72L and a treble reproduction speaker 7.
Left front speaker device with 1L 7L
, a left rear speaker device 8L having at least a bass reproduction speaker 82L and a treble reproduction speaker 81L, and a right front speaker device 7 having at least a bass reproduction speaker 72R and a treble reproduction speaker 71R.
R and at least the bass reproduction speaker 82R
and a right rear speaker device 8R having a high frequency reproduction speaker 81R, and the positive end of the high frequency reproduction speaker 71L of the left front speaker device 7L is connected to the first output terminal 41L.
, the negative end of the bass reproduction speaker 72L of the left front speaker device 7L is connected to the first output terminal, and the negative end of the bass reproduction speaker 72L of the left front speaker device 7L is connected to the second output terminal 42L. The positive end of the treble reproduction speaker 71R of the right front speaker device 7R is connected to the third output terminal 41R, and the negative end is connected to the ground, and the positive end of the bass reproduction speaker 72R of the right front speaker device 7R is connected to the third output terminal 41R. The negative end of the third output terminal is connected to the fourth output terminal 42R, the positive end of the treble reproduction speaker 81L of the left rear speaker device 8L is connected to the first output terminal 41L, and the negative end is connected to the fourth output terminal 42R. The negative end of the treble reproduction speaker 81R of the right rear speaker device 8R is connected to the negative terminal, and the positive end of the bass reproduction speaker 82L of the left rear speaker device 8L is connected to the first output terminal 41.
L, the negative terminal is connected to the second output end 42L, and the right rear speaker device 8R is connected to the second output end 42L.
The positive end of the treble reproduction speaker 81R is connected to the third output terminal 41R, and the negative end is connected to the negative end of the treble reproduction speaker 81L of the left rear speaker device 8L. The positive end of the bass reproduction speaker 82R is connected to the third output terminal 41R.
A sound field reproducing device characterized in that negative terminals are respectively connected to the fourth output terminal 42R. The negative terminal of the bass reproduction speaker 82L of the left rear speaker device 8L is connected to the second output terminal via the variable resistor 9L, and the negative terminal of the bass reproduction speaker 82L of the right rear speaker device 8R is connected to the second output terminal.
The negative terminal of R is connected to the fourth output terminal via the variable resistor 9R, and the negative terminal of each of the treble reproduction speakers 81L, 81R of the left and right rear speaker devices 8L, 8R is connected to the variable resistor 10. The sound field reproducing device according to claim 1, wherein the sound field reproducing device is connected to the ground through the utility model.