How Does The Public Address System Constitute?

- Sep 13, 2018-

Public broadcasting belongs to a branch of sound reinforcement engineering, while sound reinforcement engineering is an interdisciplinary subject involving various disciplines such as electroacoustics, architectural acoustics, and music theory. Each type of sound reinforcement equipment can be divided into four parts: program source equipment, signal processing equipment, transmission lines and speaker systems.

Program source device: The program source is usually provided by a tuner (receiver), a CD player and a card holder, in addition to a microphone, an electronic musical instrument, and the like.

Signal processing equipment: including mixers, preamplifiers, power amplifiers and various controllers and audio processing equipment. The primary task of this part of the device is signal amplification, followed by modification, mixing or selection of the signal. The mixer and the preamplifier are similar in function. Of course, the mixer has higher functions and performance indicators. Their basic functions are to complete the signal selection and preamplification, and also to adjust and control the volume and sound effects. . In order to better perform tone modification and compensation, a graphic equalizer is sometimes added. The role of the power amplifier is literally understood: power amplification allows the speaker to output enough sound power. Although the transmission line is simple, it has different requirements depending on the signal transmission method. The wireless, small signal, frequency modulation and other transmission methods are not discussed here. Only the most commonly used power transmission lines are discussed. For auditoriums, theaters, etc., because the distance between the power amplifier and the speaker is not far, the sound quality is also very high. Therefore, the direct feeding method with low resistance and large current is adopted, and the transmission line requires a dedicated speaker cable. For the public address system, because of the wide service area and long distance, in order to reduce the loss caused by the transmission line, high-voltage transmission is often used. The power transmission wire of the public address system accounts for a large investment cost, so the calculation method of the wire material often becomes a problem for many engineers.

Speaker system: The speaker system requires that the entire project system be matched and its distribution coordinated with the environment. The auditorium, theater, and dance halls have high volume and sound quality requirements, so speakers generally use high-power speakers (tens to hundreds of watts); public broadcasting systems, because of their low volume and sound quality requirements, mostly use a few watts of low power speaker system. Due to the long transmission distance and large loss of public broadcasting, the sensitivity of the speaker system is usually required to be sufficiently high. In addition to the need for good sound reinforcement equipment in the sound reinforcement project, it is very important to have a good sound reinforcement environment.



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