Microphone squealing and noise

- Apr 11, 2020-

In the construction of a microphone system, we often encounter the problems of noise and screaming. Let's explain the practical solutions to these two problems in detail.

1. Noise problem: the main performance is that the speaker has noise, noise or current sound without sound source.

2. Whistling problem: the main performance is that the microphone gain can not be raised or the volume can not be raised, which will generate sound feedback and whistling.

First step

First, eliminate the external factors; cause the current sound or noise problems. There are only three external reasons. The external sound source equipment, the site environment noise is too large and the system power supply has problems. Let's eliminate one by one. First, take down the external sound source, then turn off all the microphones on site, cut off the pick-up of environmental noise on site, and then confirm whether this power supply shares the same power supply with other large-scale power systems. Because if it shares a power supply with other large-scale electrical systems, its use will greatly affect the change of current, so it will produce current sound.

The second step

Gradually eliminate various problems in the internal system; in this step, I sorted out my own common methods:

1. The minimum system method: in our system, it is usually composed of the former equipment, the peripheral equipment and the later equipment. First, we remove all the peripheral equipment, such as: the mixer is connected to the power amplifier, the power amplifier is connected to the speaker, to see if there is any noise, if there is any, we also give up the mixer, if there is any, it is the background noise of the power amplifier, which belongs to the quality problem, we can only replace it, because we are not repairing the equipment, ha ha. If not, it is the setting of the mixer is not correct or the quality is not good. See if the gain is adjusted too much. If there is no problem with the minimum system, it must be a problem with the discarded pile of peripherals. At this time, we need to add peripherals one by one, and then check in detail whether it is a problem with device settings or quality. For example, whether the noise reducer is adjusted well, whether the equalizer gain is too large, etc

2. Replacement method: in many projects, there may be more than one system, and the same equipment may have two or more. We will replace the equipment found to be faulty by another one that has been debugged in other conference rooms. If the problem is solved, it is the problem of the equipment. If the problem still exists, there are other problems in the system that you haven't found yet. We need to check it carefully again.


3. Instrument measurement method: through multimeter, level meter and other measuring instruments, measure whether the speaker impedance and output level of step-by-step equipment are normal.

Through the above steps and methods, I believe that the noise problem in the system will be solved soon.

The third step

Solve the problem of squealing. This problem is caused by the sound of the speaker being transmitted to the microphone to form a circuit, and after several times of amplification, squealing occurs. A better way is to physically block the path between the two. For example, when we choose the microphone, we should try to choose the directional one instead of the non directional one. In the process of using, the microphone should not face the speaker as much as possible. However, because there are multiple microphones, the speaker placement is fixed and cannot be changed, so we can only use peripheral equipment to complete this function, such as feedback suppressor, smartlive to find the scream point, and attenuate the corresponding frequency point on the equalizer