JPH0221835Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a sound quality switching circuit for a microphone.

Conventionally, in order to change the sound quality of an electrodynamic microphone, it has been carried out to cut out the low frequency components of the output signal.

An example of this type of circuit was the one shown in FIG.

In the figure, 1 is an electrodynamic microphone unit, 2 is a choke coil with a low-pass characteristic of -6 dB/Oct, and 3 is a sound quality switch for selecting whether or not to connect the choke coil 2 in parallel to the output of microphone unit 1. The switch and 4 are output terminals as a microphone.

The audio signal output from the microphone unit 1 is (a) when the switch 3 is open, it is directly supplied to the output terminal 4, and (b) when the switch 3 is closed, only the low frequency component is sent to the yoke coil 2. Since the remaining mid-range to high-range components are supplied to the output terminal 4, the output voltage as a microphone has a low-cut characteristic of +6 bB/Oct.

This situation is shown in FIG.

In this example, the cutoff frequency is approximately 200Hz.

Conventional sound quality switching circuits were constructed in this way, but had the disadvantage that when the low range was cut, the overall output energy was lower than when the low range was not cut, and the auditory sensitivity was lowered.

Therefore, switching the sound quality while inputting audio sounds unnatural, and the volume of the microphone amplifier must be adjusted each time, which creates a restriction that the cutoff frequency of the chiyoke coil cannot be set too high. As a result, it was not possible to make a large change in sound quality.

The purpose of the present invention is to provide an improved sound quality switching circuit that overcomes the drawbacks of the above-mentioned conventional techniques and has a sufficient change in sound quality by preventing the auditory sensitivity from decreasing even when the sound is low-cut. It is in.

Hereinafter, the present invention will be specifically explained with reference to the drawings.

FIG. 3 is a circuit diagram of a microphone sound quality switching circuit according to an embodiment of the present invention.

What is important in the figure is that the chiyoke coil 2
In addition to 0, a resistor 30 having an impedance lower than that of the chiyoke coil 20 is provided in parallel with the resistor 30.
A changeover switch 40 is provided. 4
1 and 42 are contact points of the switch 40.

Next, the operation of the present invention will be explained.

(A) When the selector switch 40 is at the contact 41, only the low frequency component of the audio signal output from the electrodynamic microphone unit 10 is -6 dB/
Oct, and the mid to high frequency components are output from output terminal 5.
(B) When the selector switch 40 is at the contact 42, the resistor 30 has no frequency characteristic and the output voltage as a microphone has a low-cut characteristic of +6 dB/Oct. Since the impedance is set to a lower impedance than that of the microphone unit 10, the frequency characteristics of the output signal of the microphone unit 10 remain the same, and the output signal with a level lower than the level of the non-low-cut midrange to high range in case (A) above is output to the output terminal. 50.

Figure 4 shows the output voltage characteristics.

In this example, the level difference (sensitivity difference) between case (A) and case (B) is from midrange to 1000Hz or higher.
There is only about 2dB in the high range, and it feels like the same level to the ear.

FIG. 5 is a circuit diagram of a microphone sound quality switching circuit according to another embodiment of the present invention.

What is important in the figure is that the sound quality switching element is
As the cut-off frequency of each switch coil of the elements 31, 32, and 20 increases, the level of the mid-range to high-range range increases sequentially, and the number of contacts of the changeover switch 40 is increased accordingly. This is what is happening.

Thereby, it is possible to switch the sound quality in three or more stages. Element 11 is for short circuit (switch OFF).

In this case, the output from the microphone unit 10 is shunted by the resistor element, and the sensitivity of the microphone decreases in the elements 30, 31, and 32 including the resistor. If this is not possible, a step-up transformer 60 may be provided immediately after the microphone unit 10, as shown in FIG.

Note that the level (sensitivity) correction performed by this circuit at the time of switching is not only performed to maintain the same audible level, but also to set the audible level to be higher at the switch position with a higher cutoff frequency. The intelligibility of the sound produced by the range cut may be enhanced.

As explained above, according to the present invention, it is possible to solve the conventional drawback that the audible sensitivity decreases when the output of the microphone unit is cut in the low range with a chiyoke coil, so the cutoff frequency can be set arbitrarily. , it is possible to realize microphone sound quality switching with sufficient variation without unnaturalness due to sensitivity variation. Furthermore, changes in sound quality can be checked and compared while the volume of the microphone amplifier, etc. is fixed at one point, and an appropriate switch device can be selected.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a conventional sound quality switching circuit, Fig. 2 is an output voltage characteristic diagram of the circuit shown in Fig. 1, Fig. 3 is a circuit diagram of a sound quality switching circuit according to an embodiment of the present invention, and Fig. 4 is its output voltage characteristic diagram, and FIG. 5 is a circuit diagram of a tone quality switching circuit according to another embodiment of the present invention. 10... Electrodynamic microphone unit, 20...
...Chiyoke coil, 30...Resistor, 31, 32...
...Series element of resistor and chiyoke coil, 40...Sound quality selection switch, 50...Output terminal.

Claims (1)

[Scope of utility model registration request] In a sound quality switching circuit that cuts low-frequency components of the output signal of an electrodynamic microphone, a low-frequency cutting coil and a resistor are connected in parallel to the output of the microphone unit via a changeover switch, and the coil and resistor are connected in parallel to the output of the microphone unit. A sound quality switching circuit for a microphone, characterized in that the sound quality switching circuit can be switched by a changeover switch.