Wireless microphones, also called wireless microphones, can realize sound restoration and amplification. Compared with wired microphones, they are more convenient and more and more favored by consumers. They are widely used in KTV, audio-visual rooms, conference rooms and other occasions. Perhaps many people still think this way: as long as you connect to the device, you can talk. In fact, if you don’t understand its working principle and precautions, you can’t really use wireless microphones. Next, let's share with you this knowledge.
The working principle of wireless microphone:
The wireless microphone is mainly composed of a transmitting part and a receiving part. The transmitting part is powered by a battery. The microphone converts the sound into an audio electric signal, and after processing by an internal circuit, it emits radio waves containing audio information into the surrounding space. The receiving part is generally powered by the mains power. The receiving antenna receives the radio wave from the transmitting part, processes the internal circuit to extract the audio signal, and sends it to the sound reinforcement system through the output signal line, thereby completing the wireless transmission of the audio signal .
After knowing how it works, let's take a look at the precautions for using wireless microphones.
1. Impedance matching
When using a wireless microphone, the output impedance of the wireless microphone and the input impedance of the amplifier are the same as the best match. If the mismatch ratio is more than 3:1, the transmission effect will be affected. For example, when a 50Ω wireless microphone is connected to an amplifier with an input impedance of 150Ω, although the output can increase by nearly 7db, the high and low frequency sounds will suffer significant loss.
2. Working distance and proximity effect
Generally, the working distance between the wireless microphone and the mouth is 750px-1000px. 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 the strong signal, and the low-frequency sound will be too heavy and affect the clarity of the language. This is because the directional microphone has a "close-talking effect", that is, the low-frequency sound will be significantly improved when speaking at a close distance. However, sometimes singers deliberately use the "near-talking effect" to make the singing effect more beautiful and pleasant.
3. The angle between the sound source and the wireless microphone
Each wireless microphone has its effective angle. Generally, the sound source should be aimed at the center line of the wireless microphone. The greater the deflection angle between the two, the greater the treble loss. Sometimes when a wireless microphone is used, there is a "loud" sound. At this time, it can be reduced by deflecting it some angle.
4. The position and height of the wireless microphone
When amplifying the sound, do not place the wireless microphone close to the speaker or aim at the speaker first, otherwise it will cause howling.
The height of the wireless microphone should be placed according to the height of the sound source. If one person speaks or several people sing, the height of the wireless microphone should be the same as the singer’s mouth: when there are many people, the wireless microphone should be placed at an average height and appropriate Arrange the position of the singer, accompaniment, and various instruments in the team. Don't make the sound too loud, light or too light, and make all sounds within the effective angle of the wireless microphone.
The wireless microphone should be prevented from knocking or falling during use. It is not advisable to test the microphone by blowing or tapping, otherwise it is easy to damage the wireless microphone.
When the wireless microphone is used outdoors or when recording voices, a windshield should be used to avoid recording the "pop" sound of the wind. The windshield also prevents dust from contaminating the wireless microphone.
5. Take out the battery in time when not in use
The wireless microphone is battery powered. If the voltage drops, the sensitivity will decrease and the distortion will increase. Therefore, when the sound becomes worse, check the battery voltage, turn off the power switch when the wireless microphone is not in use, and remove the battery when the wireless microphone is not used for a long time.