1. Program source equipment: There are traditional program sources such as a digital tuner, multimedia player and so on, and intelligent program sources such as digital program control center, campus broadcast player, digital sound source control machine, CNC MP3 player and so on. All of them are devices that have built-in digital sound sources and can control related systems. There is other program source equipment such as radio broadcast, CD player, recording cassette, microphone, electronic musical instruments, etc.
2. Signal amplifiers include equalizer, preamplifier, power amplifier, various control equipment and audio processing equipment. The primary task of the signal amplifiers is signal amplification, followed by signal selection. The function and status of the sound console and preamplifier are similar (of course, the function and performance indexes of the sound console are higher). Both of their basic functions are to complete the signal selection and the preamplification and to adjust and control the volume and sound effect in addition. Sometimes in order to achieve better frequency equalization and timbre beautification, the graphic equalizer is also added separately. This part is the "control center" of the entire pa(public address) sound box system. The power amplifier amplifies the power of the signals sent by the preamplifier or sound console and then drives the loudspeaker to sound through the transmission line.
3. Transmission line: Although the transmission line is simple, the requirements vary with different systems and transmission ways, it is generally divided into four kinds, they are an analog audio circuit, digital twisted pair line, streaming media (IP) data network line, and NC optical fiber line.
As for the hall and theater, because the distance between the power amplifier and the loudspeaker is not too long, the direct feed mode of low resistance and a large current is generally adopted, and the transmission line requires a special horn line. As for the public broadcasting system, because of the wide service area and long distance, the high voltage transmission is often used in order to reduce the loss caused by the transmission line. Because the transmission current is small, the demand for the transmission line is not very high, and generally using the common audio line is enough, which belongs to the analog audio circuit.
4. Loudspeaker system: The loudspeaker system which is a kind of cordless pa system requires the matching of the whole system, and the selection of its position should be in accordance with the reality. Generally, floral horn, indoor sound column, wall hung sound box or suspended sound box can be used indoors. Outdoor sound column, lawn special sound box, horn, etc. can be used outdoors.