JPH05145991A - Low frequency range characteristic correcting circuit - Google Patents

Abstract

PURPOSE:To correct a hearing characteristic in the case of low volume and to suppress excess volume by controlling the amplification factor of a low frequency range corresponding to the level of an input signal while passing only the low frequency range through a signal compressing circuit. CONSTITUTION:The input signal of an input terminal 1 is divided into a high- pass filter 3 and a low-pass filter 4, and the output of the filter 4 is passed through a signal compressing circuit 5 and added with the output of the high- pass filter 3 by an adder 6. In this case, in the signal compressing circuit 5, the lower the input level is than a reference level, the more the amplification factor is increased, and the more the level is than the reference level, the more an attenuating amount is increased. Thus, the hearing feeling when the low frequency signal at a low level is corrected, and the distorting feeling can be suppressed when the signal is at a too much higher level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bass range characteristic correction circuit in a voice amplifier circuit.

[0002]

2. Description of the Related Art Conventionally, as a technique in this field, a volume controller is used as shown in FIGS. 4 and 5 in order to correct the characteristic that human hearing makes it difficult to hear sounds in the low range when the volume is low. By controlling the correction of the low frequency range characteristic in conjunction with it, if the overall attenuation of the volume control is set to a large value, the low frequency range attenuation is made relatively small, and as a result, it seems that the low frequency range is enhanced. Conversely, if the overall attenuation of the volume control is set to a small value, the attenuation in the low range becomes equal to the overall attenuation, and the amplification rate in the low range decreases. Had occupied.

[0003]

However, in the circuit having the above-mentioned structure, the average level of the input signals is different even if the audio signals have the same contents because the enhancement ratio in the low frequency range is linked to the volume controller. However, when listening at a similar volume, the degree of the effect is different, and there is a problem that it is not possible to effectively correct the low range in the sense of hearing when the volume is low.

[0004]

In order to solve the above problems, the present invention uses a signal compression circuit to control the amplification factor in the low frequency range in accordance with the level of an input signal, and at the time of low volume. It is intended to effectively correct the low range in the sense of hearing.

[0005]

According to the present invention, as described above, since the amplification ratio of the low frequency range is controlled according to the level of the input signal or the level of the low frequency range component, if the audio signals of the same content are input, Even if the average level of the signal is different, the effect is the same when listening at the same volume, and it is possible to effectively perform the correction of the low frequency range in the sense of hearing when the volume is low.

[0006]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration block diagram of a bass range characteristic correction circuit showing a first embodiment of the present invention, and FIG. 2 is a schematic configuration block diagram of a bass range characteristic correction circuit showing a second embodiment of the present invention. Is.

In FIG. 1, 1 is an input terminal, 2 is an output terminal, 3 is a high frequency band pass filter, 4 is a low frequency band pass filter, 5 is a signal compression circuit, and 6 is an addition circuit.

In FIG. 1, the signal input to the input terminal 1 is divided into a path that passes through a high frequency band pass filter 3 and a low frequency band pass filter 4, and the signal compression circuit 5 outputs from the output of 4.
The output of the treble filter 3 is added to the output of the treble band pass filter 3 by the adder circuit 6 and output. At this time, as shown in FIG. 3, the input / output characteristics of the signal compression circuit 5 are such that the amplification factor increases as the level decreases when the input level is lower than a certain reference input level, and the level increases when the input level is higher than the reference input level. Since the amount of attenuation increases as much as possible, there are two actions, that is, the audible correction when the bass signal is at a low level and the distortion feeling when the signal is at an excessive level are suppressed.

In FIG. 2, 7 is an adder circuit. Figure 2
In, the sound signals input to the respective channels are added by the adder circuit 7, then passed through the low-pass filter 4, the output thereof passes through the signal compression circuit 5, and the adder circuit 6 passes through the high-tone region of each channel. It is added to the output of the filter 3 and output. As a result, if the circuit configured in the first embodiment requires two channels for stereo and the localization of the low frequency range does not pose a problem, only one signal compression circuit 5 is needed, and a circuit of equivalent performance is cheaper. Can be configured.

The present invention is not limited to the above-described embodiments, and various modifications can be made based on the spirit of the present invention, for example, all circuits are performed by digital signal processing. It is not excluded from the scope of the invention.

[0012]

As described above in detail, according to the present invention, the amplification factor increases as the level becomes smaller when the input level is lower than a certain reference input level, and increases as the level becomes higher than the reference input level. Since a signal compression circuit that increases the amount of attenuation is inserted in the low-frequency range path, there are two effects: low-frequency range correction on the auditory sense when the audio signal is at a low level, and suppression of distortion at an excessive level. can get. It can also be realized at low cost.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a bass range characteristic correction circuit showing a first embodiment of the present invention.

FIG. 2 is a schematic block diagram of a bass range characteristic correction circuit showing a second embodiment of the present invention.

FIG. 3 is an input / output characteristic diagram of a signal compression circuit according to an embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a conventional circuit.

5 is a schematic diagram of operating characteristics of the circuit of FIG.

[Explanation of symbols]

 1 Input Terminal 2 Output Terminal 3 High Band Pass Filter-4 Low Band Pass Filter-5 Input / Output Characteristics of Signal Compression Circuit 6 Addition Circuit 7 Addition Circuit

Claims (2)

[Claims] 1. A 1-channel input / output terminal, a high-pass filter and a low-pass filter that receive signals from the input terminal as inputs, and an output of the low-pass filter as input. A signal compression circuit for compressing the signal, and an addition circuit for synthesizing the output of the signal compression circuit and the output of the treble band pass filter,
The lower the volume, the higher the amplification rate in the bass range, and conversely, the higher the volume, the lower the amplification rate.By doing so, it is possible to suppress the lack of bass at low volumes and the distortion of the bass range at excessive volumes. Low range characteristic correction circuit. 2. A two-channel input / output terminal, a two-channel high-pass filter and a summing circuit for two-channel input signals, each of which receives a signal input from the input terminal, and an adding circuit for the two-channel input signal. A low-pass filter having an output as an input, a signal compression circuit that receives the output of the low-pass filter as an input, and compresses an input signal, and an output of the signal compression circuit and each output of the high-frequency pass filter are combined. And an adder circuit for 2 channels
The lower the volume, the higher the amplification rate in the low frequency range, and conversely, the higher the volume, the more the attenuation increases, thereby suppressing the lack of bass at low volume and suppressing distortion in the low frequency range at excessive volume. Low range characteristic correction circuit.