Talking about the causes of professional audio noise.KTV audio manufacture

　　1. Electromagnetic radiation interference noise

　　Environmental stray electromagnetic wave radiation interference, such as high-frequency electromagnetic wave radiation interference of mobile phones, walkie-talkies and other communication equipment, electric pulse radiation such as elevators, air conditioners, automobile ignition, electric welding in the surrounding environment, and studio lighting control using thyristor rectifier control equipment. The generated radiation will be directly mixed into the transmission signal through the audio transmission line to form noise, or pass through the casing of the poorly shielded equipment to interfere with the internal circuit of the machine to generate interference noise. Practice has shown that in some special occasions, such as a studio where a large number of thyristor dimming devices are used, if reliable shielding and grounding measures are not taken, the noise will be very serious.

　　2. Power supply interference noise

　　External interference of professional audio equipment, in addition to electromagnetic vehicle radiation, the introduction of interference noise from the power supply will be another main cause of noise. Due to the common access of various lighting equipment, power equipment and control equipment, the urban power grid has formed a very serious source of interference. For example, lighting control equipment, air conditioners, motors and other equipment connected to the same power grid will generate peak pulses, inrush currents, and ripple voltages of different frequencies on the power line. A part of the interference noise cannot be effectively filtered by the power circuit of the audio equipment, which will inevitably form noise inside the equipment. In particular, the high-power equipment that does not meet the requirements of electromagnetic compatibility in the same power grid is the main reason for interfering with audio equipment.

　　3. Ground loop noise

　　In the audio system, the whole system must be well grounded, and the grounding resistance is required to be less than 4 ohms. Otherwise, the induced charges generated by the equipment in the audio system due to various radiation and electromagnetic induction will not be able to flow into the ground, thus forming a noise voltage superimposed on the audio signal.

　　If there is a ground potential difference between the ground wires of different devices due to the difference in ground resistance, or if there is a loop in the internal ground of the system, ground noise will be caused. When two different audio systems are interconnected, noise may also be generated. The noise is caused by the direct connection of the ground wires of the two systems.

　　4. Circuit noise inside the device

　　Audio equipment has one indicator - signal-to-noise ratio. Due to the electrical noise generated by the internal electronic components, when one device works alone, it can achieve the required specifications, but when multiple devices are cascaded, the noise will accumulate and increase. In practical applications, some low-grade civil audio equipment will have a lot of AC noise due to the poor filtering of the internal power supply, and sometimes serious noise will be formed in the audio system.

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