working principle
At present, karaoke microphones widely used in commercial karaoke dance halls and home karaoke systems can be divided into wired karaoke microphones and wireless karaoke microphones.
As the name suggests, the wired karaoke microphone's output signal is sent to the sound reinforcement equipment through a cable. Its structure is shown in Figure 1.

The commonly used wired karaoke microphones are mainly dynamic coils. Its working principle is: when sound waves act on the microphone diaphragm to make it vibrate, the voice coil adhered to the diaphragm also corresponds in the magnetic circuit air gap The ground vibrates and cuts the magnetic lines of force, generating an induced electromotive force in the voice coil. However, the electromotive force of the microphone output is very low, usually a step-up transformer is connected to the output end of the microphone in order to match with the audio equipment. Karaoke microphones are used at close range. In order to achieve good results, the microphones are required to have special close-talk effects and pointing effects to improve performance and resist environmental interference. In other words, the sensitivity of the microphone changes with the distance of the sound source at the low frequency end: the closer the distance, the higher the low frequency sensitivity. The high-value karaoke microphone is also equipped with an explosion sound filter, which minimizes excessive breathing noise and popping noise, and realizes complete and full sound reproduction. Another important feature of karaoke microphones is that the microphone shell is equipped with a control switch, which allows you to achieve some special sound effects when singing. Specially designed anti-vibration measures can effectively prevent the friction noise when holding, so that your singing has clear bass, bright high-pitched and sweet, soft and beautiful sound quality, full of infectious. The domestic famous brand karaoke microphones mainly include Prime series karaoke microphones. This series of microphones is the preferred product for karaoke dance halls and home karaoke systems. The home-use karaoke microphone is represented by the CDK404 in a metal case. It is available in black and silver gray. Its main technical performance is as follows: frequency response is 100Hz ~ 10kHz, output impedance is 600Ω ± 30%, free field sensitivity is -54dB (1kHz), weight is 300g. The wireless karaoke microphone's cable restricts the free movement space of the singer due to the cable of the wired karaoke microphone, thus affecting the singer's passionate performance and moving range. The wireless karaoke microphone came into being. Figure 2 is a block diagram of the electrical principle of a wireless karaoke microphone. |

The sound head of the wireless karaoke microphone converts the acoustic signal into an electrical signal, and the electrical signal performs frequency modulation on a carrier wave, and the frequency-modulated carrier radio signal is transmitted by the antenna. After the radio signal is received by the FM receiver, the sound signal is restored and sent to the karaoke machine. The transmission frequency of wireless karaoke microphones used in homes is mostly in the range of 88 ~ 108MHz. It is designed to borrow the recorder with FM band as the receiving device of wireless karaoke microphones to save money. The power of the transmitter is not large, about 100mW, so as not to interfere with other electrical equipment. Professional wireless karaoke microphones work in the high-end frequency band (150-216MHz) or ultra-high frequency band (400-470MHz, 900-950MHz) of ultra-high frequency band, and are equipped with a dedicated FM receiver. Wireless karaoke microphones all use frequency modulation, because frequency modulation has the advantages of strong anti-interference, wide frequency characteristics, high fidelity, low noise, and high transmitter efficiency. Key points for using karaoke microphone Pay attention to the following points when using a karaoke microphone: (1) The output impedance of the karaoke microphone should match the input impedance of your karaoke machine; (2) When using more than two karaoke microphones, the The phase should be unified; (3) Before use, the volume of the karaoke machine should be adjusted properly to avoid burning the amplifier and speakers at a large volume. (4) Do not cover the net cover with your hands or block the sound hole during use, so as not to affect the performance of the microphone and reduce the singing effect. (5) When storing the microphone, it should be dust-proof, shock-proof, moisture-proof and anti-magnetic. |

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