How to deal with the noise in the small speaker system?

Noise is a type of small speaker sound that causes irritability, or is too loud and endangers human health. From the perspective of environmental protection: all sounds that hinder people's normal rest, study and work, and sounds that interfere with the sounds people want to hear are all noise. From the perspective of physics: noise is the small speaker sound made by the sounding body when it vibrates irregularly.

By defining noise, we can find that noise in a broad sense or a narrow sense refers to the small speaker sound we don’t need. Its existence not only affects the acceptance and discrimination of normal small speaker sound signals, but also in such a noise environment for a long time. It has a substantial impact and damage to human emotions and auditory system.

In the small speaker audio and video industry, especially on-site construction, noise is what we often say about a certain system. The most painful thing for the on-site small speaker audio engineers is that after the entire system is completely set up, all the equipment is installed, and during debugging, it is found that the speakers are rustling or crackling of firecrackers. The better situation is that noise occurs during the installation and debugging stage. We can also find the problem to avoid embarrassing situations when it is given to the user. And if it has been delivered and used, such a sudden situation can be said to be a nightmare for every engineering person.

To solve this problem, you need to analyze the root causes of noise one by one, and investigate one by one. Problems can not be absolutely avoided, but the rigorous use of professional knowledge and good operating habits can greatly reduce the probability of noise. This article mainly sorts out How the noise is generated in the small speaker sound reinforcement system, and some measures on how to deal with it, for your reference.

Generally speaking, distinguished by source, noise can be divided into three types:

1. Human factors

Specifically refers to signal interference outside the signal system, noise generated by switches, interference signals from other systems, and industrial ignition radiation, which can be classified as man-made noise sources;

2. Natural factors

Normally, natural discharge phenomena such as lightning and interference of various electromagnetic waves are natural sources of noise;

3. Internal factors

Internal factors, as the name implies, mean that the source of noise is related to the components of the small speaker sound reinforcement system equipment. Such noise generation usually refers to interference signals caused by semiconductor carrier changes or electronic thermal movement in the device.

The above three types of noise, among which man-made and natural factors have obvious characteristics, can theoretically find the source to effectively control and deal with it, but the noise we usually face and need to be dealt with is generated randomly, and random noise can also be divided. There are three types:

1. Single frequency noise

Continuous sine wave signal interference, but the initial phase, frequency and amplitude are irregular, the frequency band is narrow, and the frequency position can be measured;

2. Impulse noise

Discrete pulses with large amplitude and short time are characterized by high noise and pauses in the middle, mostly from electrical interference, lightning weather;

3. Fluctuation noise

It is caused by thermal noise and shot noise, which is greatly affected by the environment, and has obvious characteristics but strong randomness.

According to the above classification, it can be seen that the single-frequency noise is easy to control, and the pulse type has a long quiet period in the middle, so the overall effect of our sound reinforcement system will be less affected for a long time. The ups and downs are more random, not easy to control, and unavoidable.

The main noises discussed in this article are as follows

1 Electromagnetic radiation interference

Generally, it is caused by electromagnetic radiation and pulse radiation generated by the operation of some equipment such as induction cooker, microwave oven, large screen, air conditioner, elevator, or mobile phone communication in the environment where the system is located. Corresponding need to adopt corresponding shielding treatment, or isolate the interference source from the small speaker sound reinforcement system as much as possible. Such as the use of ferrite materials for equipment isolation or the use of better shielded cables.

2 Power interference

The pulse interference formed by the power supply of the equipment, or the voltage and current enter the small speaker sound reinforcement system, or the electromagnetic compatibility performance in the power grid does not reach a reasonable standard. This kind of situation is mostly the interference of the video system. It is necessary to reduce the voltage drop between different devices in the system, which can be carried out with appropriate wiring, either to ensure complete common ground or complete disconnection.

3 Ground loop voltage

The grounding resistance is less than 4Ω, which is the grounding standard that all small speaker sound reinforcement systems should meet. Generally, there is more than one device in the small speaker sound reinforcement system, and the non-correspondence of the resistance causes a certain potential difference and forms an interference signal. The corresponding treatment method is: in addition to ensuring that the equipment is well grounded (the system grounding resistance can be measured), the small speaker audio system is dedicated to grounding, and the equivalent point is the same, that is, there is no potential difference. Separate from lights, large screens and other equipment to completely avoid noise caused by grounding problems.

4 Equipment circuit problems

The internal circuit design of the equipment is unreasonable, or the background noise caused by poor products. Excluding the above-mentioned situations, then we can use the method of cross-testing to verify whether the equipment is a problem again, and replace the good equipment after positioning.

The above are several common noises and corresponding treatment methods. Of course, the complexity of the scene cannot be unified. In addition to these basic understandings, detailed analysis is needed to help us quickly find the cause and solve the problem. In addition, if you encounter some single-frequency noise, such as some fixed-frequency device local noise, you can use the mixer or the equalizer in the digital small speaker audio processor to adjust.