What causes noise in professional audio

　　What causes noise in professional audio

　　1. Circuit noise inside the device

　　Professional audio equipment has an indicator-signal-to-noise ratio. Due to the electrical noise generated by the internal electronic components, when one device works alone, the required index can be achieved, but when multiple devices are cascaded, the noise will accumulate and increase. In practical applications, some low-grade civilian audio equipment will have a lot of AC noise due to poor internal power supply filtering, which will sometimes cause serious noise in professional audio systems.

　　2. Power interference noise

　　The external interference of professional audio equipment, in addition to electromagnetic car radiation, the introduction of interference noise in the power supply part will be another main cause of noise. The urban power grid has formed a very serious source of interference due to the joint access of various lighting equipment, power equipment, and control equipment.

　　For example, lighting control equipment, air conditioners, motors and other equipment connected to the same power grid will generate spikes, surge currents, and ripple voltages of different frequencies on the power line, which will enter the power supply of professional audio equipment through the power line. There will be some interference noise that cannot be effectively filtered by the power circuit of the audio equipment, and noise will inevitably form inside the equipment. Especially high-power equipment with electromagnetic compatibility in the same power grid that does not meet the requirements is the main reason for interference with audio equipment.

　　3. Electromagnetic radiation interference noise

　　Environmental stray electromagnetic radiation interference, such as high-frequency electromagnetic radiation interference of communication equipment such as mobile phones and walkie-talkies, electrical pulse radiation such as elevators, air conditioners, car ignitions, and electric welding in the surrounding environment. 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 poorly shielded equipment and interfere with the internal circuit of the machine to generate interference noise. Practice has shown that in some special occasions, such as studios where a large number of thyristor dimming equipment is used, if reliable shielding and grounding measures are not taken, the noise will be very serious.

　　4. Ground loop noise

　　In a professional audio system, the entire system must be well grounded, and the grounding resistance must be less than 4 ohms. Otherwise, the induced charges generated by the equipment in the professional audio system due to various radiation and electromagnetic induction will not be able to flow into the ground, resulting in 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 there is a loop in the internal ground of the system, ground noise will be caused. When two different professional 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

　　Professional audio equipment has an indicator-signal-to-noise ratio. Due to the electrical noise generated by the internal electronic components, when one device works alone, the required index can be achieved, but when multiple devices are cascaded, the noise will accumulate and increase. In practical applications, some low-grade civilian audio equipment will have a lot of AC noise due to poor internal power supply filtering, which will sometimes cause serious noise in professional audio systems.

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