Indoor setup of public address speakers

2022 08/16

When designing a PA loudspeaker system for sound reinforcement, the sound field of sound reinforcement should be considered first, that is, to have a solid grasp of the acoustic characteristics of the sound reinforcement room, and to study what kind of speakers should be used and how to install them to make it work. Due to the differences in the environment, sometimes it is difficult to obtain excellent sound reinforcement only according to the function and arrangement of the horn speakers. For example, in a gymnasium without acoustic treatment, after the sound is amplified, a clear sound cannot be obtained due to severe reverberation, and it is difficult to eliminate special reflections such as reflections and flutter reflections only by sound reinforcement equipment. Therefore, if the acoustic characteristics of the room are not good, it will not be possible to obtain excellent sound reinforcement. The acoustic characteristics are excellent, but the placement method is not good, and it is also impossible to obtain excellent sound reinforcement.

The placement design of the speakers should be adapted to the shape, size, reverberation time, and purpose of use of the room. The following points can be considered: 1. The sound pressure distribution throughout the room should be uniform; 2. There will be no special reflections that deteriorate the clarity. ③It is not easy to cause feedback oscillation formed by the feedback loop of the speaker-microphone-amplifier-speaker, that is, howling.

For the public address system, the sound field quality of the speaker box hanging on the side wall is higher. However, due to the convenience of installation and concealment, the solution of installing ceiling speakers on the ceiling has been taken over by people, and it is widely used in hotel corridors, shopping malls and other places where the ceiling is not very high.

The physical meaning of the speaker enclosure area is shown in Figure l. In the figure, a indicates the cover angle, H indicates the height of the ceiling (m), h indicates the average height of the ear plane (m), and r is the radius of the bottom circle of the cylinder (m). According to the area of a certain place and related data, the number of required ceiling speakers can be estimated. In principle, the distribution of the ceiling loudspeakers is aimed at making the final sound pressure level more uniform.

The selection of ceiling loudspeaker should consider the main technical indicators such as rated power, flexibility, frequency response range, size, etc. The size of the speaker is related to the cover angle.

When laying the trunk line, a metal partition can be added in the metal trunking, and the public broadcasting line can be laid on one side individually.

In the "Code for Design of Automatic Fire Alarm System" (GB50116-98), the laying requirements of emergency broadcast lines are not specified in detail, but Article 10.2.2 stipulates that when fire control, communication and alarm lines are laid in dark, it should be The metal pipe or the rigid plastic pipe treated with flame retardant shall be protected, and shall be laid in the protective layer of the non-combustible body, and the thickness of the protective layer should not be less than 3mm. When it is laid in the open, it should be protected by metal pipes or metal trunkings, and fire protection methods should be used on the metal pipes or metal trunkings. Since the broadcast circuit is similar to the alarm circuit during fire rescue, the laying design should be carried out in strict accordance with the laying requirements of the alarm circuit.