The selection of microphones should be based on the occasion of use and the requirements for sound quality, combined with the characteristics of various microphones, and comprehensive consideration. For example, high-quality recording and broadcasting, the main requirements of good sound quality, capacitive microphone, aluminum microphone or advanced moving coil microphone should be selected; For general amplification, the ordinary moving coil type can be selected; When the speaker's position moves from time to time or the distance between the speaker and the amplifier is large, such as karaoke singing, a microphone with unidirectional and low sensitivity should be used to reduce noise interference. The use of capacitive microphone requires phantom power supply, generally in the microphone technical parameters within the description of the power supply voltage, to choose the appropriate voltage of the phantom power supply, the mixer is generally equipped with 48V phantom power supply.

The selection of microphones should be based on the occasion of use and the requirements for sound quality, combined with the characteristics of various microphones, and comprehensive consideration. For example, high-quality recording and broadcasting, the main requirements of good sound quality, should choose capacitive microphone, aluminum microphone or advanced moving coil microphone, such as karaoke singing, should choose a single directional, low sensitivity microphone.

In use should also pay attention to:

1. Impedance matching

When using a microphone, the output impedance of the microphone and the input impedance of the amplifier are the same, and if the loss ratio is more than 3:1, it will affect the transmission effect. For example, when the 50Ω microphone is connected to the input impedance of 150Ω amplifier, although the output can be increased by nearly 7Db, the high and low frequency sound will be significantly lost.

2. Connect the cable

The output voltage of the microphone is very low, in order to avoid loss and interference, the connection line must be as short as possible, high-quality microphone should choose a double-core twisted metal shielded wire, general microphone can use a single-core metal shielded wire. High impedance microphone transmission line length should not exceed 5 meters, otherwise the treble will be significantly lost. The connection of low resistance microphone can be extended to 30m- 50m.

3. Working distance and close talking effect

Usually, the working distance between the microphone and the mouth is 750px- 1000px is appropriate, if the distance is too far, the reverberation will increase, and the noise will increase relatively; If the working distance is too close, the signal will be distorted due to too strong, and the low-frequency sound will be too heavy and affect the clarity of the language. This is because the directional microphone has a "proximity effect", that is, when broadcasting at close range, the low frequency sound will be significantly improved. Sometimes, however, the singer takes advantage of the "close talk effect". Make the singing effect more wonderful, pleasant.

4. Angle between sound source and microphone

Each microphone has its effective Angle, the general sound source should be aligned with the microphone center line, the greater the deviation Angle between the two, the greater the treble loss. Sometimes when you are using a microphone, there is a "chirping" sound, which is lessened by deflecting the microphone at an Angle.

5. Microphone position and height

In the amplification, the microphone should not be placed near the speaker or aligned with the speaker first, otherwise it will cause whistling.

The height of the microphone should be determined according to the height of the sound source, if it is a person speaking or several people singing, the height of the microphone should be consistent with the singer's mouth; When there are a large number of people, the microphone should be placed at an average height, and the position of the singer and accompaniment and various instruments in the team should be appropriately deployed, so that the sound is not too loud, the light is too light, and all the sound should be within the effective Angle of the microphone. If there is a lead singer or leader, a special microphone should be placed if necessary.

When several microphones are needed at the same time, the parallel connection method can be adopted, but attention must be paid to the phase problem of several microphones. When the phase is consistent, it can be connected in parallel with each other, otherwise it will interfere with each other, reducing the output and distorting. Different models and different impedance microphones should not be used in parallel, because the high impedance microphone "short circuit", so that the output voltage is very low. Under normal circumstances, microphones are used directly in parallel, and the effect is not as good as a single microphone.

If several microphones are used at the same time for a person to speak, rather than separate several places for different purposes, then the microphone is still selected for the same model. Otherwise, the tone of the speech will change due to the speaker's movement or change of Angle.

The microphone should be used to prevent knocking or falling. It is not appropriate to test the microphone by blowing or tapping, otherwise it is easy to damage the microphone.

When the microphone is used or recorded outdoors, the wind hood should be used to avoid the "puffy" sound of the wind. The storm hood also prevents dust from staining the microphone.

When using a wireless microphone, note:

(1) Select the location of the receiver so that it avoids the "dead center".

(2) When receiving, adjust the Angle of the receiving antenna, adjust the frequency, and adjust the volume to make it in the best state.

(3) The antenna of the wireless microphone should naturally sag and expose the clothing.

(4) Prevent the polarity of the battery from being reversed, and remove the battery in time after use.

Some microphones (e.g., electret capacitor microphones, wireless microphones) are battery powered. If the voltage drops, the sensitivity will decrease and the distortion will increase. Therefore, when the sound deteriorates, the battery voltage should be checked, the power switch should be turned off when the microphone is not used, and the battery should be removed when it is not used for a long time.