JPH0227618Y2 - - Google Patents

Description

[Detailed description of the invention] Purpose of the invention: [Industrial field of application] This invention relates to a sound quality adjustment circuit, and is particularly used in the field of adding a function of blocking noise generated in the high frequency range.

[Prior Art] As a sound quality adjustment circuit for adjusting the sound quality in the treble range, there is a circuit diagram shown in FIG. 4A. The characteristics of this circuit are shown in FIG.

[Problems to be solved by the invention] The conventional sound quality adjustment circuit shown in Figure 4 can enhance or attenuate the high frequency range as shown in the characteristic diagram shown in Figure 4, but it is not necessary to attenuate the high frequency range. When investigating some cases, most of them are used to remove tape noise when using tape as the source, high frequency noise when using FM broadcast radio waves, high frequency noise when using AM broadcast radio waves, etc. ing. When used to remove such noise, it is preferable that the characteristic in the high frequency range be a cutoff characteristic rather than a stepped attenuation characteristic as shown in FIG. 4B.

This idea was made in view of the above points, and it is a sound quality adjustment that can adjust the sound quality in the high range, and also has the function of blocking noise components generated in the high range while adjusting the cutoff frequency appropriately. It was created for the purpose of providing a circuit.

Structure of the invention: As shown in the circuit diagram of Fig. 1, the sound quality adjustment circuit of this invention connects the ground side terminal 3a of the volume control variable resistor VR3, which is equipped with an intermediate tap terminal 3b, to the earth line. The tap terminal 3b is connected to the ground line via the first resistor _R1 , and the hot side terminal 3c is connected to the first variable resistor VR1, which has a resistor section and a short-circuit section within the sliding section of the sliding piece. A second resistor section is connected to the input terminal IN through
Connect the sliding terminal 2b of the variable resistor VR2 to the hot side terminal 3c of the variable resistor VR3 for volume adjustment,
The ground side terminal 2a on the short-circuit section side is connected to the ground line via the first capacitor _C1 , and the hot side terminal _2c on the resistor section side is connected in series with the second resistor _R2. It is connected to the intermediate tap terminal 3b of the volume control variable resistor VR3 via the second capacitor _C2 , and the second variable resistor is connected at the position where the sliding piece of the first variable resistor VR1 slides on the resistor section. The sliding piece of the second variable resistor VR2 slides on the short-circuit section, and at the position where the sliding piece of the second variable resistor VR2 slides on the open section or the resistor section, the first variable resistor
This is a configuration in which the sliding piece of VR1 is interlocked so that it slides on the short-circuit section. In other words, when the sliding piece of the first variable resistor VR1 slides on the resistor section and enters the short-circuit section, that is, when it is located at the boundary between the short-circuit section and the resistor section, the second The sliding piece of the variable resistor VR2 is located in the open section, and then when the sliding piece of the first variable resistor VR1 slides on the short-circuit section, the sliding piece of the second variable resistor VR2 is located in the open section. Slide on the body section.

Figures 2A and 2B show an equivalent circuit when the treble range is enhanced and an equivalent circuit when the treble range is cut off in the circuit diagram [Fig. 1] shown as the sound quality adjustment circuit of this invention. FIG. 3 shows a characteristic diagram of the equivalent circuit diagrams of FIGS. 2A and 2B. When the treble range is enhanced, the same operation as the conventional example is performed.

From the equivalent circuit when the high frequency range is cut off, the cutoff angular frequency ωc is ω _C = {(R ₁ + R ₃₁ ) (Rg + R ₁₁ + R ₄ + R ₃₂ ) + R ₁・
R ₃₁ } / [C ₁ (Rg + R ₁₁ + R ₄ ) {R ₃₂ (R ₁ + R ₃₁ )
R ₁・R ₃₁ }] …(1) The transfer function e ₀ /e _i is given by e ₀ /e _i = (R ₁・R ₃₁・ω _C /{(R ₁ +R ₃₁ )(Rg+
R ₃₂ + R ₄ + R ₃₂ ) R ₃₂ ) + R ₁・R ₃₁ } (S + ω _C )
...(2) = (R ₁・ R ₃₁ ) / [{(R ₁ + R ₃₁ ) (Rg + R ₁₁ +
R ₄ + R ₃₂ ) + R ₁・R ₃₁ }{j(ω/ω _C )+1}]
...(3) becomes.

The cutoff angular frequency ω _C in equation (1) is the first variable resistor VR
When the variable resistance value R ₁₁ of 1 becomes smaller, the cut-off angular frequency ω _C becomes smaller, and when the variable resistance value R ₁₁ becomes larger, the cut-off angular frequency ω c changes to become larger.

The transfer function e ₀ /e _i in equation (2) is the first variable resistor VR
When the variable resistance value R ₁₁ of 1 becomes smaller, the attenuation in the treble range becomes smaller, and when the variable resistance value R ₁₁ becomes larger, the attenuation in the treble range becomes larger.

The transfer function e ₀ /e _i in equation (3) has a slope of - from the asymptote of OdB/oct. at any cutoff angular frequency ω _C.
It changes so that the slope of the song characteristic follows an asymptote of 6 dB/octave.

Effects of the invention: The sound quality adjustment circuit of this invention not only enhances the characteristics of the treble range stepwise and can variably adjust the sound quality, but also adjusts the cutoff angle according to the type of noise when removing noise in the treble range. Since the frequency can be variably adjusted and it is attenuated at -6 dB/oct., noise removal is superior to that of conventional circuits.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram explaining this invention, Figure 2 A and B are respectively exploded circuit diagrams of Figure 1, and Figure 3 is an exploded circuit diagram of Figure 1.
The figure is a characteristic diagram of this invention, and FIG. 4 is a circuit diagram showing a conventional example. VR1...First variable resistor, VR2...Second variable resistor, VR3...Volume adjustment variable resistor, R ₁
...First resistor, _R2 ...Second resistance, C1 _... First capacitor, _C2 ...Second capacitor, IN...Input terminal, OUT...Output terminal, 1a, 2a, 3a...
...respectively sliding pieces, 1b, 2b, 3b...resistor section, 1c, 2c...respectively short circuit section, 2d
...Open section.

Claims (1)

[Scope of utility model registration request] Connect the ground side terminal of a variable resistor for volume adjustment equipped with an intermediate tap terminal to the earth line, connect the intermediate tap terminal to the earth line via the first resistor, and connect the hot side terminal to the sliding piece of the sliding piece. Connected to the input terminal via a first variable resistor having a resistor section and a short-circuit section within the section, and a resistor section, an open section, and a short-circuit section within the sliding section of the sliding piece. second
The sliding terminal of the variable resistor is connected to the hot side terminal of the variable resistor for volume adjustment, the ground side terminal on the short circuit section side is connected to the ground line via the first capacitor, and the terminal on the resistor section side is connected to the intermediate tap terminal of the volume adjusting variable resistor via a second resistor and a second capacitor connected in series with the second resistor, so that the sliding piece of the first variable resistor is on the resistor section. At the position where the sliding piece of the second variable resistor slides on the short circuit section, and at the position where the sliding piece of the second variable resistor slides on the open section or the resistor section. A volume control circuit in which a sliding piece of the first variable resistor is interlocked to slide on a short-circuit section.