JPH02148903A - Sound quality adjustment circuit - Google Patents

Abstract

PURPOSE:To obtain a change in a frequency band different at emphasis and at attenuation by forming a series resonance circuit with a 1st capacitor and a semiconductor inductor and connecting the capacitor in series at the attenuation of a variable resistor. CONSTITUTION:A capacitor 14 is connected to the position of a fixed terminal 3a of a variable resistor 3 and when a slider 3c is fully turned to the position of the fixed terminal 3a, the capacitor is connected in series with a capacitor 11 and the capacitor 11 and the semiconductor inductor 13 constitute a series resonance circuit. Then the series resonance frequency is increased at attenuation more than that at emphasis. Thus, the resonance frequency at emphasis is set to an ultralow frequency band and that at attenuation is brought to a lower limit the sound band. Thus, sufficient attenuation even of a music is sensed at attenuation and a powerful low sound frequency is emphasized at the emphasis.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to audio equipment, particularly to a sound quality adjustment circuit such as a radio receiver or a cassette tape recorder with a radio.

Conventional technology A conventional example will be explained below with reference to FIG.

Reference numeral 1 denotes an audio signal input terminal, which is connected to a signal source (not shown) (tuner, tape deck, etc.).

2 is an audio signal output terminal, which is connected to a power amplification circuit (not shown). Reference numeral 3 denotes a variable resistor that changes the sound quality, and has fixed terminals 3a, 3b and a movable terminal 3C.In the case of a stereo configuration, the left and right two are generally linked. Furthermore, in the case of a stereo configuration, two sets of circuits, left and right, are required, but only one channel is shown here. 4 and 5 are operational amplifiers, 6, 7, 8, 9.10 are resistors, and 11° and 12 are capacitors. Here, the operational amplifier 6° resistors 9, 10. Capacitor 12 constitutes semiconductor inductor 13 .

L by the capacitor 11 and the semiconductor inductor 13
A C series resonant circuit is constructed, and the series impedance becomes very distinct at the series resonance point. When the movable terminal 3c of the variable resistor 3 approaches the fixed terminal 3a side, only the frequency component at the resonance point in the input signal from the input terminal 1 is attenuated due to voltage division with the resistor 6, and is input to the positive input of the amplifier 4. In order to enter
The signal output to the output terminal 2 is a signal in which only the resonance point is attenuated. Conversely, when the movable terminal 3C of the variable resistor 3 approaches the fixed terminal 3b side, the amount of negative feedback by the resistors 7 and 8 decreases, so that the signal output to the output terminal 2 is emphasized only near the resonance point. This situation is shown in Figure 4, where if the series resonance frequency in the bass range is f, this frequency f0 is the frequency at which emphasis or attenuation is adjusted.
Output characteristic B is this frequency f. Centering on the terminal 3a side 1. of the variable resistor 3. In accordance with the change in midpoint, 3b, B1.
It changes to B2°B3. That is, at the position of the series resonance frequency f determined by the values of the capacitor 11 and the semiconductor inductors 1 and 3, sound quality adjustment is performed by emphasizing and attenuating the frequency f0 as the center.

Problems to be Solved by the Invention However, in the above-mentioned conventional circuit, the frequencies to be emphasized and attenuated (the set low frequency range) are the same, and therefore there are the following problems. That is, in general, in order to make a powerful change, it is necessary to change the low frequency range (50 to 80 Hz). However, in the case of music songs, there are many that contain almost no sound in this low frequency range (60 to 5 oHz), and in order to obtain a large audible change range, a change range of ±20 dB or more is required. On the other hand, if such a change is made, clipping distortion will occur even if the volume is slightly increased, especially in devices with low maximum output such as radios and radio cassette players, so it is necessary to add a circuit to attenuate the amount of emphasis when the amplitude is large. , the frequency band (f. above) to be changed as the bass range must be 150 to 300 with a signal.
There was a problem in that the frequency had to be increased to Hz or other means.

In view of the above-mentioned problems, the present invention has been developed as a sound quality adjustment circuit in the low frequency range, so that sufficient audible changes can be obtained even with a small change width, and when the attenuation is performed, even musical songs can feel that the attenuation is sufficiently attenuated. The object of the present invention is to provide a tone quality adjustment circuit capable of emphasizing a certain single tone.

Means for Solving the Problems In order to solve the above problems, the sound quality adjustment circuit of the present invention includes an amplifier, a variable resistor for bass level adjustment provided on the input side of the amplifier, and a movable terminal of the variable resistor. a semiconductor inductor connected in series to the first capacitor, and a second capacitor connected to the attenuation side terminal of the variable resistor;
A series resonant circuit is formed by the capacitor and the semiconductor inductor, and a second
The first capacitor is connected in series with the first capacitor.

Effects of the present invention With the above-described configuration, the series resonance frequency when emphasized is set to a higher resonance frequency during attenuation by the second capacitor than when emphasized, and changes in frequency bands that are different between the times of emphasis and attenuation are obtained. will be possible.

Embodiment An embodiment of the present invention will be described below based on FIG. 1, but the same contents as those in FIG. 3 of the conventional example will be given the same reference numerals and the explanation will be omitted.

14 is a capacitor, which is connected to the fixed terminal 3a of the variable resistor 3.
When the movable terminal 3C is changed to the fixed terminal 3&, it is connected in series with the capacitor 11, and thus forms a series resonant circuit together with the capacitor 11 and the semiconductor inductor 13. It turns out.

Therefore, the resonance frequencies 11 and 12 during emphasis and attenuation are
is amplifier 5. Resistors 9, 10, 1:/Since the dancer 12 constitutes a semiconductor inductor, it is expressed by the following equation.

・・・・・・・・・・・・・・・(1)・・・・・・・・・
・・・・・・・・・(2) However, R9 and R1゜ are resistances 9
, 10 resistance value [Ω] C11C12C14 is the capacitance CF of capacitors 11, 12, 14) Therefore, the relationship between fl and f2 is expressed by the above equation (1) and (2).
From the formula, capacitors 11, 12, 140fflK
Therefore, it can be set freely.

FIG. 2 shows an example of frequency versus output characteristics that can be realized by the present invention. The output characteristic A is the characteristic A1 when the movable contact 3c of the variable resistor 3 is at the midpoint position, whereas the movable contact 3c
At the position where the fixed contact 3b is changed to the emphasis side, the output characteristic A2 is emphasized around the resonant frequency f1, while at the position where the movable contact 3c is changed to the attenuation side of the fixed contact 3a, the output characteristic is emphasized around the resonant frequency f2. This results in an attenuated output characteristic A3. Here, the resonance frequencies f1 and f2
As mentioned above, is determined by equations (1) and (2), but the resonance frequency 11 at the time of emphasis is, for example, in the deep bass range (6
On the other hand, the resonant frequency f2 at the time of attenuation is, for example, the lower limit of the audio band (160-300Hz).
), resistor 9, 1o and capacitor 11゜1
By setting the values of 2.14, it is possible to emphasize the deep bass range and to substantially attenuate the audio lower limit band where there is always a perceptual signal.

Effects of the Invention As described above, according to the present invention, the series resonant frequency is made higher during attenuation than when it is emphasized. Since the lower limit can also be set, a large audible change can be obtained with a relatively small amount of change even in music with a low signal level in the deep bass range. Therefore, while avoiding clipping distortion at maximum volume in audio equipment with little output margin such as radio cassette players and radios, it is possible to obtain a large audible change when adjusting the sound quality in the bass range, and the effect is very large. It is something.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of one embodiment of the present invention, Fig. 2 is an example of a circuit diagram of advanced technology, and Fig. 4 is a frequency vs. output characteristic obtained by conventional technology. Variable resistor, 4...Amplifier, 1
1...First capacitor, 13...Semiconductor inductor, 14...Second capacitor. Name of agent: Patent attorney Shigetaka Awano and 1 other person No. 3
Figure Chi O Hara 5 Nu So

Claims (1)

[Claims] an amplifier, a variable resistor for bass level adjustment provided on the input side of the amplifier, a first capacitor connected to a movable terminal of the variable resistor, and a semiconductor connected in series to the first capacitor. It includes an inductor and a second capacitor connected to the attenuation side terminal of the variable resistor, the first capacitor and the semiconductor inductor form a series resonant circuit, and the second capacitor is connected to the attenuation side terminal of the variable resistor. A sound quality adjustment circuit characterized in that a capacitor is configured to be connected in series with a first capacitor.