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Noise exclusion method:
Public broadcasting system howling in current acoustic elimination
An overview of noise and howling:
The noise is usually poor sound quality, the sound is not clear, there will be noise in the background if no music is played. The whistling is usually caused by the distance between the microphone and the speaker when speaking, or the improper installation angle of the speaker. During the debugging of the public broadcasting system and background music system, sometimes the speaker may have current noise or generate microphone whistle. How can this situation be solved?
First of all, we analyze the noise problem. The noise is mainly reflected in the noise, noise, or current sound of the speaker in the absence of sound.
Secondly, we analyze the howling problem. The main problem of the howling problem is that the microphone gain cannot be raised or the sound volume is not raised. When the sound volume is large, sound feedback occurs and the howling occurs. First eliminate external factors that cause current noise or noise problems. There are generally three external causes. They are caused by problems with external audio equipment, excessive ambient noise, and power supply to the system. At this time, you need to calm down and remove one by one, first remove the external sound source, turn off all the microphones that are turned on at the scene, isolate the pick-up of the ambient noise on the site, and then check whether the power source on this road is connected with other large-scale power supplies. The system shares a power supply. Because if you share a power supply with other large-scale power systems, its use will greatly affect the current changes, and therefore produce a current sound.
Second, gradually eliminate various issues of the internal system. In this step, I have organized my own methods:
1. The minimum system method: In our system, it usually consists of sound source equipment, pre-equipment, peripheral equipment, and power amplifier equipment. We first remove the peripheral equipment, for example: the mixer is connected to the amplifier, the amplifier is connected to the speakers to see if there is any noise. If so, we have also put down the mixer, and if so, it is the amplifier noise floor. . If not, it is the mixer's settings are incorrect or quality problems, see if the gain is too large. If there is no problem with the minimum system, then it is certainly a pile of problems that have been abandoned. At this time, we must add the peripheral devices one by one, and then check in detail whether it is equipment setting or quality issues. For example, if the noise reducer is adjusted properly, if the equalizer gain is too large, etc.......
2, replacement method: In many projects, the system may have more than one, the same equipment may have two or more, we check out the equipment that is considered faulty, replace a no problem equipment, the same settings, test, If the problem is solved, it is a problem with the equipment. If the problem persists, there are still other problems in the system. You haven't found it yet. We need to re-examine it carefully.
3, meter measurement method: Through multimeter, level meter and other measuring instruments, measuring speaker impedance, level by level device output level is normal.
Through the above steps and methods, I believe that the noise problems existing in the system will soon be solved.
Howling elimination method:
The whistle is generated because the sound of the speaker is transmitted to the microphone to form a loop, and after a plurality of times, the whistling occurs. The best way is to physically block the path between the two. For example, if we choose to use the microphone as much as possible, we should use directional rather than non-directional (omnidirectional mic). In the process of use, the microphone should try not to Is facing the speaker. However, because there are multiple microphones, the placement of the speakers is fixed and cannot be changed. Then we can only use peripheral equipment to complete this function, such as feedback suppressors, equalizers and other controls.