JPH04320199A - Acoustic reproducing device - Google Patents

Abstract

PURPOSE:To attain amplitude correction not giving effect on a medium frequency by solving a problem that even the medium frequency not requiring correction is corrected in the case of the correction resulting in not making the characteristic flat so as to emphasize only a low frequency and a high frequency of an acoustic signal. CONSTITUTION:The title device is provided with an amplitude correction circuit comprising the series connection of a secondary high pass filter 10 whose Q is set to be 3.0 or over and a secondary low pass filter 11 whose Q is set to be 3.0 or over, with a power amplifier 12 amplifying and reproducing the output and a speaker 13. Thus, it is possible to realize amplitude correction to emphasize only a low and a high frequency of an acoustic signal and not to give effect on a medium frequency, and a flat in-room acoustic characteristic is realized.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound reproduction device for improving room acoustic characteristics.

0002

BACKGROUND OF THE INVENTION In recent years, sound reproduction devices using amplitude correction circuits that change the amplitude characteristics of acoustic signals have been widely used as a method of correcting and flattening room acoustic characteristics that lack low and high frequencies. Currently, little consideration is given to amplitude correction means. A conventional sound reproduction device will be explained below. FIG. 8 is a block diagram showing an example of a conventional sound reproduction device. 1 is an acoustic signal source such as a tuner, tape deck, or compact disc player; 2 is an amplitude correction circuit; 3 is a power amplifier; and 4 is a speaker.

FIG. 9 is a circuit diagram of an amplitude correction circuit 2 composed of resistors 5, 6 and capacitors 7, 8, and FIG. 10 is an amplitude frequency characteristic diagram of the amplitude correction circuit 2.

[0004] The operation of the sound reproducing apparatus constructed as described above will be explained below. First, the signal sent from the acoustic signal source 1 is sent to the amplitude correction circuit 2 shown in FIG. 9, where the low and high frequencies of the amplitude characteristic are emphasized as shown in FIG. 10, and the signal is amplified by the power amplifier 3. and is reproduced by the speaker 4. As a result, the amplitude correction circuit 2
It is possible to obtain room acoustic characteristics in which the low and high frequencies are corrected, which is insufficient with only a sound reproduction device without.

[0005]

[Problems to be Solved by the Invention] However, in the conventional configuration described above, there is a limit to the amount of correction due to the characteristics of the amplitude correction circuit 2, and if sufficient correction is made to the low and high frequencies, unnecessary frequencies from 500Hz to 5KHz will be lost. The problem is that the correction is applied to the midrange, and the reproduced room acoustic characteristics are not flat as shown in FIG. 11.

The present invention solves the above-mentioned conventional problems, and aims to provide an audio reproduction device that emphasizes only the low and high frequencies of an acoustic signal and realizes amplitude correction without affecting the midrange. This is the purpose.

[0007]

[Means for Solving the Problem] In order to solve this problem, the sound reproduction device of the present invention includes a second-order high-pass filter with a Q set to 3.0 or more, and a second-order high-pass filter with a Q set to 3.0 or more. 2
It consists of an amplitude correction circuit configured by connecting low-pass filters in series, a power amplifier that amplifies the output of this amplitude correction circuit, and a speaker that reproduces the output of this power amplifier.

[0008]

[Operation] This configuration makes it possible to perform amplitude correction that emphasizes only the low and high frequencies of the acoustic signal without affecting the midrange.
Flat room acoustic characteristics can be achieved.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a sound reproduction device according to an embodiment of the present invention. In FIG. 1, 9 is an acoustic signal source such as a tuner, tape deck, or compact disc player; 10 is a second-order high-pass filter; 11 is a second-order low-pass filter; 12 is a power amplifier;
13 is a speaker.

The operation of the sound reproducing apparatus constructed as above will be explained below. First, the output of the acoustic signal source 9 is input to a second-order high-pass filter 10. As shown in FIG. 2, the second-order high-pass filter 10 includes a resistor 14
, 15, capacitors 16 and 17, and one amplifier 18, and the input/output transfer function is expressed by the equation (1).

[0011]

[Math 1]

The low cutoff frequency of the second-order high-pass filter 10 and Q indicating the sharpness of resonance are expressed by equations (2) and (3).

[0013]

[Math 2]

[0014]

[Math 3]

Here, in order to set the Q to 3.0 and the low cutoff frequency to 50Hz, the resistor 14 is set to 1.8KΩ, the resistor 15 is set to 68KΩ, the capacitor 16 is set to 0.27μF, and the capacitor 17 is set to 0.27μF. By setting constants for each, the amplitude frequency characteristics can have a peak near the low cutoff frequency, as shown in Figure 3, and 500H
A level difference of about 10 dB from the midrange range above z can be secured. In other words, the amplitude frequency characteristic of the second-order high-pass filter 10 emphasizes the low frequency range.

Next, the output of this second-order high-pass filter 10 is input to a second-order low-pass filter 11. As shown in FIG. 4, the secondary low-pass filter 11 includes resistors 19 and 20.
, capacitors 21 and 22, and one amplifier 23, and the input/output transfer function is expressed by the equation (4).

[0017]

[Math 4]

The high cutoff frequency of this second-order low-pass filter 10 and Q indicating the sharpness of resonance are expressed by equations (5) and (6).

[0019]

[Math 5]

[0020]

[Math 6]

[0021] Here, the resistor 19 is set to 1.8 kΩ so that the Q is 3.0 and the high-frequency cutoff frequency is 15 KHz.
Resistor 20 is 1.8kΩ, capacitor 21 is 0.027μ
When the constants of F and capacitor 22 are set to 0.0012μF, the amplitude frequency characteristics can have a peak near the high cutoff frequency, as shown in Figure 5, and the level difference with the midrange below 5KHz. approximately 10dB can be secured. In other words, the amplitude frequency characteristic of this second-order low-pass filter 11 emphasizes the high frequency range. This 2
The output that has passed through the second-order low-pass filter 11 has an amplitude-frequency characteristic that is a combination of the amplitude-frequency characteristics of the second-order high-pass filter 10, as shown in FIG. This is because the output impedance of the output of the secondary high-pass filter 10 is lowered by the amplifier 18, so that it does not become a load on the subsequent secondary low-pass filter 11 and does not affect the amplitude frequency characteristics. When this output is added to the power amplifier 12 and reproduced by the speaker 13, an output that corrects the room acoustic characteristics lacking in low and high frequencies is obtained, and a flat room acoustic characteristic as shown in FIG. 7 is obtained.

As described above, according to this embodiment, Q is set to 3.
A second-order high-pass filter 10 set to 0 and a Q of 3.0.
By providing an amplitude correction circuit configured by serially connecting secondary low-pass filters 11 set to It becomes possible to perform corrections that do not affect the emphasized midrange, and it is possible to achieve flat room acoustic characteristics.

In the above embodiment, active filters were used for the secondary high-pass filter 10 and the secondary low-pass filter 11, but the secondary high-pass filters 10 and 2
The low-pass filter 11 may be a passive filter. In this case, since no amplifier is required, the circuit configuration becomes simple. Furthermore, it is needless to say that it is not necessary to set Q to 3.0 for both the low and high frequencies with respect to the amount of amplitude to be corrected, and it may be set to 3.0 or more. Furthermore, in the above embodiment, the second-order low-pass filter 11 is connected in series after the second-order high-pass filter 10, but the second-order high-pass filter 10 is connected in series after the second-order low-pass filter 11. It may be configured as follows.

[0024]

As described above, the present invention provides an amplitude correction circuit comprising a second-order high-pass filter that emphasizes the low range of the amplitude characteristic of an acoustic signal and a second-order low-pass filter that emphasizes the high range. This creates an amplitude characteristic that emphasizes only the low and high frequencies of the acoustic signal and does not affect the midrange, and provides an excellent output that compensates for room acoustic characteristics that lack low and high frequencies. This makes it possible to realize a sound reproduction device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a sound reproduction device according to an embodiment of the present invention.

[Figure 2] Circuit diagram of the second-order high-pass filter

[Figure 3] Same 2
Amplitude-frequency characteristic diagram of an order high-pass filter

[Figure 4] Circuit diagram of the second-order low-pass filter

[Figure 5] Amplitude frequency characteristic diagram of the second-order low-pass filter

[Figure 6] Amplitude frequency characteristic diagram when the second-order high-pass filter and second-order low-pass filter are connected in series

[Fig. 7] Indoor acoustic characteristic diagram by the sound reproduction device in one embodiment of the present invention

[Figure 8] Block diagram of a conventional sound reproduction device

[Figure 9] Circuit diagram of the same amplitude correction circuit

[Figure 10] Amplitude frequency characteristic diagram of the same amplitude correction circuit

[Figure 11
】Indoor acoustic characteristics diagram using the same sound reproduction device

[Explanation of symbols]

9 Acoustic signal source 10 Second-order high-pass filter 11 Second-order low-pass filter 12 Power amplifier 13 Speakers 14, 15, 19, 20 Resistors 16, 17, 21, 22 Capacitors 18, 23
amplifier

Claims (1)

[Claims] Claim 1: A second-order high-pass filter whose input is an electrical signal corresponding to the sound to be reproduced and whose Q is set to 3.0 or more, and a second-order low-pass filter whose Q is set to 3.0 or more. An audio reproduction device comprising: an amplitude correction circuit configured by connecting the amplitude correction circuit in series; a power amplifier that amplifies the output of the amplitude correction circuit; and a speaker that reproduces the output of the power amplifier.