JPS6123862Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a graphic equalizer used for correcting the frequency characteristics of audio equipment and correcting the sound field.

Traditionally, graphic equalizers are used to correct frequency characteristics, and most have a variation range of ±10dB to ±12dB, but when you want a subtle change or for recording, etc., a variation range of ±12dB is not required. In this case, the range of change is too wide, making it difficult to set the adjustment knob.

The present invention solves the above conventional problems by switching the variable range of the graphic equalizer.

A detailed description will be given below with reference to the drawings.

Before explaining the embodiment of the present invention, the conventional graphic equalizer shown in FIG. 1 will be explained. In Figure 1, 1 is an input terminal, 2 is an output terminal, 3 is an amplifier, R ₁ is a feedback resistor, R ₂ is an output resistor, VR ₁ to _{VR o} are variable resistors whose middle point is grounded,
F ₁ to F _o are resonant circuits with resonant impedance r.

In Fig. 1, when the variable terminal of a certain variable resistor is set to the (+) side, as shown in the equivalent circuit in Fig. 2, the resonant frequency of the resonant circuit connected to that variable terminal causes the amplifier 6 to The amount of feedback is reduced and its frequency is enhanced. Also, when the variable terminal of the variable resistor is set to the (-) side, as shown in the equivalent circuit in Figure 3,
The impedance of the output terminal 8 of the amplifier 9 decreases at the resonant frequency of the resonant circuit connected to the variable terminal, and the frequency is attenuated.

As described above, in the conventional graphic equalizer, the variable terminal of the variable resistor has a peak characteristic on the (+) side and a _dip characteristic on the (-) side. _P = r+R ₁ /r·R/R ₂ +R, and the maximum attenuation degree G _D is expressed as G _D = R+R ₁ /R·r/R ₂ +r from FIG. However, R is a resistance value of n variable resistors connected in parallel from one end to the middle point.

Here, if R ₁ =R ₂ , then G _P =1/G _D. Under the condition that r≪R ₁ =R ₂ ≪R, G _P =1/
G _D ≒R ₁ /r=R ₂ /r, and the degree of amplification and attenuation are determined by the resonance impedance r, feedback resistance R ₁ and output resistance.
It is determined approximately by the ratio of R ₂ .

Therefore, in the present invention, the feedback resistor R ₁ and the output resistor R ₂ are composed of a plurality of resistors and a switch for switching them, and the values of the feedback resistor R ₁ and the output resistor R ₂ are changed by the switch. By substantially switching the maximum amplification degree and the maximum attenuation degree, it is attempted to obtain a range of variation suitable for use.

FIG. 4 shows one embodiment of a graphic equalizer according to the present invention. In FIG. 4, 10 is an input terminal, 11 is an output terminal, 12 is an amplifier, 13,
14 is a changeover switch, R ₁₁ and R ₁₂ are feedback resistors, one end of which is connected to the feedback terminal of the amplifier 12, and the other end connected to the changeover switch 13, through which the output terminal of the amplifier 12 is connected. It is connected to the. On the other hand, R ₂₁ and R ₂₂ are output resistors, one end of which is connected to the output terminal 11, the other end of which is connected to a changeover switch 14, and via this changeover switch 14 to the output end of the amplifier 12.

In this way, the degree of amplification and the degree of attenuation can be adjusted approximately by changing the changeover switches 13 and 14.
It is possible to switch between R ₁₁ /r and R ₁₂ /r, r/R ₂₁ and r/R ₂₂ , and as a result, the range of change becomes narrower, making it easier to set the adjustment knob.

Other embodiments are shown in FIGS. 5, 6 and 7. Other embodiments are shown in FIGS. 5, 6, and 7. In Figure 5, the amplification degree is approximately (R ₁₁ +
R ₁₂ )/r and R ₁₁ /r, and the attenuation degree is switched approximately to r/(R ₂₁ +R ₂₂ ) and r/R ₂₁ .
In Figure 6, the amplification degree is approximately (R ₁₁ R ₁₂ )/r
and R ₁₁ /r, and the attenuation is approximately r/r.
(R ₂₁ R ₂₂ ) and r/R ₂₁ . FIG. 7 shows an embodiment in which one end of the variable resistor is connected to the input terminal of the amplifier. In the case of the configuration shown in FIG. 7, the resistance R ₃₁ ,
The value of the input resistance of the amplifier 12 may be changed by switching _R32 . In this case as well, Figures 4 to 6
The same effect as shown in the figure can be obtained.

In the above embodiment, the amplification degree and the attenuation degree are switched in two stages, but switching in three or more stages can be similarly performed.

As described above, according to the present invention, with a simple circuit,
It is possible to configure a graphic equalizer that can change the range of variation depending on the purpose of use.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a conventional graphic equalizer, and Figures 2 and 3 are the circuit diagram of a conventional graphic equalizer.
4 is a circuit diagram showing one embodiment of the graphic equalizer according to the present invention, and FIGS. 5, 6, and 7 are circuit diagrams showing other embodiments of the present invention. . 10...Input terminal, 11...Output terminal, 12...
...Amplifier, 13, 14...Selector switch, R ₁₁ ,
R ₁₂ ... Resistor for feedback, R ₂₁ , R ₂₂ ... Resistor for output, R ₃₁ , R ₃₂ ... Resistor for input, VR ₁ ~ _{VR o} ...
Variable resistor, F ₁ ~F _o ... resonant circuit.

Claims (1)

[Scope of utility model registration request] an amplifier, a plurality of variable resistors each having one end connected to a feedback circuit of the amplifier, the other end connected to an input end or an output end of the amplifier, and a midpoint thereof being grounded; A plurality of resonant circuits having different resonant frequencies are connected to the terminals, and the feedback resistor of the amplifier is composed of a plurality of resistors and a switch for switching between the resistors, and the input resistor or the output resistor of the amplifier is consists of multiple resistors and a switch to switch between those resistors,
A graphic equalizer characterized in that the variable range of the amplification degree of the amplifier can be changed by switching the feedback resistor and the input or output resistor using the changeover switch.