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The trick is to eliminate the noise caused by improper connection of the equipment
In the sound system, there is a common problem of the interconnection of the equipment. If the connection is not right, the light will make the system index drop and produce noise. Connect to do the following:
Impedance matching: in the acoustic system, almost all devices are used in the cross connection mode, that is, the output impedance of the device is very small, very large input impedance. This is because in the system, unless the signal for long-distance transmission, are generally treated as short-term. And the signal level at the bottom, the signal can be high quality transmission, and the change of the load does not affect the quality of the signal.
When the signal source is designed as a constant voltage source, or the load is much larger than the internal impedance of the signal source, the above requirements can be met. In fact, the impedance of the professional audio equipment is designed according to the above principle, the equipment interconnection adopts the cross connection mode, which is the impedance matching of the acoustic equipment.
In the design of sound reinforcement system, it is not necessary to consider the impedance problem. But when one end of the output devices need to connect multiple devices, a signal source must be used to drive several active or passive audio signal distributor load, in order to meet the requirements of impedance matching equipment (if it is two sets of equipment, and can be directly in the first level output end of the equipment).
The power amplifier is connected with the speaker according to the nominal output impedance and the input impedance of the loudspeaker box. The output impedance of the amplifier has 4 and 8 kinds of, can be connected to the 4 speakers, but also can be connected to the 8 speakers, and then can be used to connect with the speaker. When connected with 4 speakers, the output power of the amplifier is greater than 8. Two 8 sound boxes can be connected to the output end of the power amplifier, which is a working state of 4.
Tip two eliminates the inherent noise of the device itself
The sound system is composed of a plurality of devices, such as microphone, DVD card, mixer, effects, equalizer, limiter, actuator, electronic frequency divider, power amplifier and loudspeaker, each device may be the source of noise. In order to find out which unit the noise is from, it is necessary to detect the inherent noise of each unit.
Turn on the sound system: the boot sequence is in accordance with the order of the signal flow step by step. After the boot, the speaker has a noise out. We can turn off the power wireless microphone receiver, listening if there is noise if the noise disappears, then prove that the noise is generated by the wireless microphone receiver: if there is noise, that noise is not generated by the wireless microphone receiver, can detect other single element.
Tip three eliminate power interference noise
The noise light SCR: on the stage, from source noise is the biggest noise from the light SCR, because the theatre and dance hall of light and dark, not by changing the intensity of 0 ~ 220V voltage to achieve, but through the electronic circuit of controllable silicon tube conduction angle change alternating current the sine wave conduction area, to achieve control of power transmission changes.
Therefore, in the power of the positive f chord waveform is changed into a shape similar to the sawtooth wave, in the power source to produce a significant 50Hz ripple, manifested in the sound system, there is a significant noise. In order to eliminate the interference noise of the silicon controlled rectifier, the most effective way is to use the two phase power supply in the three-phase power supply to the light. So you can avoid the interference of light scr.
