【 Weak current College 】 generalized sound reproducing system contains two categories---Power By 【 China power house network 】

1. sound reinforcement system: speaker and microphone at the same sound, there are sound feedback and room resonance caused screech, distortion and oscillation phenomena. To ensure system stability and uptime, the highest available system gain than acoustic feedback self-excited 6dB gain low criticality.

2. reproducing system: the system only tape drives, CD player, sound source, microphone, sound feedback may not exist, acoustic feedback coefficient is 0, which is a special case of sound reinforcement systems.

According to the use of sound reinforcement sound system can be divided into the following categories:

1) outdoor sound reinforcement system outdoor sound reinforcement system is mainly used in the stadium, stations, parks, art Plaza, music fountain, etc. It is characterized by service area, the space is wide, background noise; sound travels to direct sound dominated; required sound pressure level is high, if there are buildings around the sound reflection objects such as, speaker layout nor do reasonable, Sonic, formed by multiple reflection exceeds 50ms latency above, double or multiple sound, serious problems such as echo occurs, impact sound clarity and sound like positioning. Outdoor system sound effect is also affected by weather conditions, wind direction and impact of environmental noise, etc.

2) indoor sound reinforcement system indoor sound reinforcement system is the most widely used system, including all kinds of theatre, Stadium, dance halls, etc. It professional is very strong, both non-language sound reinforcement, and for various theatrical performances, at the request of the sound quality is very high. System design should not only consider technical issues, but also audio related architectural acoustics. Room shape on the sound quality has a greater impact.

3) flow performance system sound reinforcement system apart from the fixed installation systems and mobile systems. Commonly used in a variety of large-scale venues [such as Stadium (Museum), art broadcast and large banquet hall, etc] non-theatrical use temporary installation system called mobile performance system. Mobile performance audio equipment must be compact, easy to carry, transport and installation, high reliability and can adapt to a variety of demanding environment. Large flows of investment, typically to professional audio company rental use.

4) public broadcasting system of public broadcasting system for hotels, commercial buildings, ports, airports, subway, schools provide background music and radio programs. In recent years, the public broadcasting system and make an emergency broadcast, and interactive fire alarm system. Public broadcasting system of control functions, such as broadcasting and all call selection broadcast function, forcing the switching function and the function of the priority right to broadcast, etc. Speaker load and dispersed, transmission lines long. To reduce the transmission line losses are generally set using 70V or 100V voltage high impedance transmission. Sound pressure level requirement is not high, the sound quality to baritone and treble-dominated.

5) Conference system with domestic and international exchanges have increased in recent years, teleconference, videoconference, and digital conference system (DCN) developed very rapidly. Conference system widely used in the Conference Center, hotels, and Government agencies.

Conference system including the Conference discuss the system, voting systems, simultaneous translation system and telephone conference system. Requirements for audio, video (image) system synchronization, all used computer control and storing session data.