As we all know, in radio, television, KTV, home theater and other audio systems, if handled improperly, easy to produce noise.
I. The causes of noise
(i) Improper grounding
In the audio system, must require the entire system to have a good grounding, grounding resistance is less than 4 ohms, or the audio system in the equipment due to a variety of radiation and electromagnetic induction generated by the inductive charge will not be able to flow human Earth, thus forming noise voltage superimposed into the audio signal.
The grounding noise is caused by the difference of grounding resistance between the wires of different equipments, or when there is a circuit inside the system. When two different audio systems are connected to each other, it is also possible to generate noise directly from the ground wires of the two systems.
(ii) noise generated by electromagnetic radiation interference
The environment of stray electromagnetic radiation interference, such as mobile phones, walkie-talkie and other communications equipment high-frequency electromagnetic radiation interference, elevators, air-conditioning and other electrical pulse interference, studio lighting control with SCR rectifier control equipment radiation, will be directly mixed through the transmission line signal formation noise. A studio is because there is a large number of SCR dimming equipment, resulting in sound amplification is always a noise.
(iii) Circuit noise inside the equipment
When a device is working alone, the electrical noise generated by the internal electronic components can meet the required standards, but after multiple units cascade, the noise will accumulate and the noise in the system is serious.
(iv) noise generated by power supply interference
Due to the common access of all kinds of lighting equipment, power equipment and control equipment, the city Power Network has formed a serious interference source. If the lighting control equipment, air-conditioning, motor and so on in the same power grid will produce Spike pulse, surge current and ripple voltage at different frequencies in the power supply line. Supply power to the device through the power cord. There's always a part. Interference noise voltage can not be effectively filtered through the power circuit of the audio device, and it will form noise inside the equipment.