【 Weak current College 】 audio noise causes

In the sound recording, live sound amplifying, sound system, noise is a widespread and very painful. Usually composed sound system equipment, or transfer out longer distance, the greater the background noise, and even makes the sound system was unable to carry out normal recording or PA work. Sound system noise mechanism of the formation of more complex, these sound system noise of the main causes of and solutions to do a study.

1. electromagnetic interference noise

Stray electromagnetic radiation in the environment, such as mobile phones, radio and other communication devices of high frequency electromagnetic wave radiation interference, the surroundings of the elevator, air conditioning, car ignition, electric welding, electrical pulse radiation, Studio light control using SCR control equipment produced by the radiation, flowing through the audio transmission line directly in the mixing transmission signal noise, or through the shield of machines and equipment of shell Jammer incircuit interference noise. Practice shows that in some special occasions, such as large-scale use of thyristor dimmer device Studio, if you do not have to take reliable measures of shielding and grounding, noise will be very serious.

2, power supply noise

Audio equipment of external interference, in addition to the electromagnetic radiation from vehicles to power part of the introduction of noise will be another major cause of the noise. City power grid, for a variety of lighting, power equipment, control equipment and common access, forming a very serious interference sources. If in the same power grid lighting control equipment, air conditioning, motors, and so on device will power lines generate peak pulse, surge current, different frequency ripple voltage, through the power line cuanru audio equipment power supply, there will always be a part of the noise cannot be through audio equipment power supply circuits effective filtering, will necessarily result in the formation of noise inside the device. In particular, the same power system electromagnetic compatibility not to require high power device is interfering with audio equipment.

3. earthing circuit noise

In audio system, you must call the whole system has a good grounding, grounding resistance requirement is less than 4 ohm. Otherwise, the sound system equipment for a variety of radiation and electromagnetic induction charge will not be able to flow into the Earth, forming noise voltage overlay in the audio signal.

If the Earth in a different device between different ground resistance to potential difference exists, or the system's internal ground loops, it can cause ground noise. Two different audio system interconnect, may generate noise, noise is comprised of two systems directly connected to the ground.

4, equipment, internal circuit noise

Audio device has a target-to-noise ratio. Due to the internal electronics electrical noise, resulting in a device to work alone, to meet the required specifications, but when more than one device concatenated, noise will increase accumulation. Practical application, some low grade civil audio equipment due to internal power filter, make the device itself ripple noise is very large, in audio system can sometimes form a very serious noise.