Professional audio system engineering design

view：938 upgrade：2018-08-18

The sound reinforcement belongs to the category of applied acoustics. No matter it is indoor or outdoor, it can not be separated from the acoustic environment (or sound field) in which the sound reinforcement is used. Therefore, the fundamental problem of the design of the sound reinforcement system is acoustic problem. Taking theater sound reinforcement as an example, the audience hall sound reinforcement system design should first consider the hall use object, architectural form, sound construction design, stage installation and facilities, and the form and requirements of performing arts closely related to the design of the sound reinforcement system. After fully understanding these basic conditions and requirements, then the selection and configuration of sound reinforcement system equipment will be carried out.

The final effect of the sound reinforcement in the auditorium is the embodiment of the comprehensive effect of the sound construction and the electroacoustic. It is the analysis and design calculation of the sound field based on the sound construction. Therefore, the fundamental problem of the design of the sound reinforcement system is the acoustic problem. The design of sound reinforcement system should start with the sound field, that is, the layout of loudspeaker system (spatial position), product selection (including combination) and power fed. It can be analyzed and compared with various schemes by means of computer aided design acoustic software, and the relevant data of acoustic characteristics of the sound amplification system are given. On this basis, the last is the structure of sound amplification system and the configuration of equipment (or equipment).

The design of sound field is the basic of the sound amplification system design. Whether it is indoor or outdoor, there is more or less interference in the field of sound amplification, which is inevitable. The existence of interference in the field of sound amplification will affect the clarity of language and music, and will damage the sound quality effect of sound amplification and playback.

The modern sound reinforcement design has no longer "satisfied" the sound pressure level and the inhomogeneity of sound field in general sense, but pays great attention to the sound interference of sound field. In the design, it is the key point of modern sound amplification design to minimize the interference and obtain a "clean" sound field.

In recent years, the software of ear, MAPP and Bose are widely used in the design of indoor and outdoor sound reinforcement system to simulate the acoustic field of the sound reinforcement system. Ease is a general software which covers the speaker database of dozens of famous speakers manufacturers in the world; Bose software is the database which only contains Bose speakers developed by the company, so it can only design and calculate Bose speakers. The software more highly advocates audible sound field simulation; MAPP software is the software developed by Meyer sound company for its own products. Meyer is said to think that the error of simulation and calculation of reverberation field is too large and it is not practical significance. Therefore, the software only simulates and calculates the direct sound field, and the software has higher accuracy in setting the division. So, how should we grasp the application of these design software correctly? The following is the focus on the ease software.

（1） .easy software brief course

Taking indoor sound reinforcement as an example, CAD of sound reinforcement system has not reached practical stage about the mid-1980s. At that time, the sound field design of sound reinforcement is usually completed by classical formula or geometric sound line drawing method, most of which can only be estimated. The practical software for the aided design of acoustic characteristics of sound reinforcement system by computer comes from the mid-1980s in the United States. After that, the internationally renowned companies have developed CAD software which can adapt to different brand speaker databases, and constantly improve the calculation methods and results display. The most representative of the time were:

Cadp-2 of JBL, the PhD program of Philips, the Bose speaker of Bose, acousta CADD software of Mark VI 'group in the United States, etc. The early CAD software of acoustic characteristics of sound reinforcement system was mostly DOS version and special speaker database (such as JBL, Bose, etc.). German ADA acoustic design company developed ease2.0 software in the early 1990s, which is a commercial software registered in many countries. Compared with the previous software, it is more abundant and perfect in the calculation content. The speaker database of the software is open and contains the database of dozens of famous brands in the world. Since 1990s, the software has been widely used at home and abroad.

In the late 1990s, ADA company upgraded and developed ease3.0 simulation software based on ease2.0 (DOS version), which is a software running in Windows environment. Obviously, the interface and windows of windows are fully reflected in ease3.0. For the establishment of acoustic model, calculation of more complex graphics (requiring large memory), graphic display and screen printing, etc., are better than the ease2.0 software of DOS version, but there is no big difference between the two in terms of basic calculation contents, Only some calculation formulas are added to the mathematical model and some calculation contents are added accordingly.

In August 2002, ADA company launched EASE4.0 version again. EASE4.0 has continued all functions of ease3.0 and made many improvements, including: humanized user interface, more convenient model import and export, richer speaker database, especially the database of line array speaker system. In other words, EASE4.0 can calculate the data of the loudspeaker system with line array, which is not completed by ease3.0, etc. At present, the ese software is widely used in the field simulation of sound amplification.

（2） The accuracy of CAD system for acoustic characteristics of sound reinforcement system

The computer aided design of acoustic characteristics of sound reinforcement system can not only integrate the relevant characteristics of sound construction and electroacoustic, but also give the specific data of acoustic characteristics of audience, and achieve quantitative design and calculation, and save a lot of working time. The expected results of acoustic characteristics of the simulated sound reinforcement system can be seen directly through CAD, which is good guidance for the actual engineering. However, we should clearly see that both the east software and the Bose and Mapp software have certain limitations in their calculation accuracy and accuracy, and the results of simulation calculation can only be used for reference.

（3） . computing software is a good tool

Nowadays, in the design of sound reinforcement system, the software of ear is widely used in the field simulation of sound reinforcement. The CAD system of acoustic characteristics of sound reinforcement system provides a new method and fast calculation for acoustical workers to design the project, which saves a lot of working time. The software is mainly used to compare the selection and layout of sound box in the same acoustic environment for electroacoustics workers, and to provide help by showing the different schemes of sound amplification field's "direction", and can not be too superstitious and depend on the results of these software calculations. It is also pointed out that the computing system can only be operated according to the "following" instruction, which can not replace the designer's deep understanding of architecture and art; It can not replace the acoustic, systematic knowledge and rich experience of designers. In short, acoustic simulation software and calculation system can not replace the design work of acoustics workers. It is only a good tool.

The theater sound amplification system is for stage performance art, it provides a high-quality sound playback platform for performing arts. According to the function orientation of theatre, the sound reinforcement system should be designed to meet the needs of different forms of performing arts. In recent years, the design of theatre sound reinforcement system has a "pattern" trend, and some misleading phenomena have appeared.

The selection and layout of the loudspeaker system in the theatre auditorium are various. Most of them are "personalized" designs, especially some professional theatres (such as opera houses) and commercial theatres, which are designed closely around the performance scenario and artistic needs. In short, we should show the full stage art expression to the maximum and the most accurate.

On the "stereo sound amplification" in the theatre auditorium

Recently, some people have overemphasized the so-called "stereo sound reinforcement" in the design of sound reinforcement system, that is, the setting of three channels, i.e. left, middle and right (LCR), and the speaker system of each channel covers the audience seat sound reinforcement in full field, which is called "stereo sound reinforcement". Even if the recorded "stereo" music program is replayed, the real stereo effect area in the auditorium seat is in the center of the audience seat, accounting for only about one fourth of the seats by quantitative analysis of the sound amplification field. The live sound reinforcement used in the actual performance cannot be called stereo sound reinforcement, but only the left, middle and right (LCR) three channels. Overemphasizing "stereo sound amplification" can lead to misleading.