【 Weak current College 】 speaker layout and installation and placement of the microphone

First, the speaker layout and installation
The entire layout of sound reinforcement system is also very important, the layout is good or bad, is directly related to the quality of sound reinforcement system as a whole.
1. speaker layout
Speaker layout, general principles to be followed are as follows:
1) makes the Hall sound field with uniform;
Line 2) audiovisual, sound cordial nature;
3) favorable overcome feedback, improve the acoustic gain;
4) line of simple, easy maintenance, adjusting the angle of coverage;
5) speaker sound than natural sound source delay 5 ~ 30ms;
6) press coverage angle speakers (4kHz, declining to axis 8kHz 6dB) coverage for all Auditorium.
2. the speaker layout
Speaker layout should be based on the architectural features, body size, space height and Auditorium settings, and other factors determine that generally consists of: decentralized, centralized, mixed layout.
1) centralized
The speakers (or speaker system) use centralized layout;
(1) set the stage and requires the Visual effect of the agreement;
(2) subject to the construction, shape restrictions should not be dispersed.
Set layout, making the audience area of direct sound more evenly and to minimize the acoustic feedback.
Centralized system with a single speaker or a group of speakers set installation.
For example there is a stage-Auditorium, speaker system, close to the natural sound sources, usually placed in the mouth above or table box sides. This arrangement has the advantage that the sound comes from the stage direction, from the Visual sense, hearing more natural. The disadvantage is that the complex shape (such as check table too deep) or large halls, sound field not uniform, even the back seat of the low sound level may, in addition, centralized layout for speaker close to the stage of the microphone, easily lead to feedback whistling.
Engineering design, note that you should choose the single direction strong speakers or sound columns, this will help to overcome the acoustic feedback. When the speakers are arranged in the mouth, from overcoming the effect of acoustic feedback than layout in both sides of the mouth. Height for space, the existence of the more obvious question is in the front row of the audience will feel the sound comes from above, in order to overcome this shortcoming, can one mouth additional speaker (speaker's power to allocate less) so that the sound field with uniform front row, so that noise down. When the speakers are arranged in one side, acoustic feedback problems outstanding, because such as speakers and sound columns, they are in the horizontal direction of directivity rather poor, simple two speakers with the power of mouth hung in Taiwan, on both sides of the Hall seats audience will produce a double source of interference, the audience was very uncomfortable, the solution is to place the speakers wherever possible, hang the higher, the appropriate additional auxiliary speaker. Other and if there are viewers of all halls, such as the Coliseum, the speaker layout in the competition Hall. Place the microphone to the performance area, care should be taken to control the speaker directivity. Due to the acoustics of a figure of complex and diverse, centralized system, which can take a number of speakers put together by different shapes of curves of configuring.
2) decentralized
The following speakers (or speaker system) should be dispersed:
(1) building lobby height is high, vertical distance long or Hall can be divided into several partial use, inappropriate use of central layout;
(2) within the Office would not be appropriate for long reverberation time, centralized.
Decentralized, should control close to the podium at the first row of the speaker's power to minimise acoustic feedback, should prevent the audience area produces double acoustic phenomena, if necessary, within the different pathways to take appropriate measures of relative time delay.
Speakers group often mounted on the ceiling or the surrounding wall. Noise level is high and not for timing analysis used in the lounge, you can also use Group distribution of speaker system, the gym generally use uniform distribution in the rings of the speaker system.
3) hybrid
The following speakers (or speaker system) use mixed layout:
(1) check out the table too deep or supposes seat theatre, etc., should be screened for some layout auxiliary speaker system;
(2) on large or vertical distance long building lobby, in addition to the focus setting speaker system, suitable for decentralized auxiliary speaker system;
(3) the Parties shall have the audience's audiovisual Hall.
On (1), (2) should solve the control sound path difference and limit the sound level of the problem, should be extended if necessary to avoid double acoustic phenomenon.
For large or long Hall, speakers often using hybrid layout, each speaker services. The advantage is that the speaker distance from audience than centralized greatly shortened, to increase the audience directly to voice and weight at the pressure level, the required power ratio of centralized layout, but it should be noted: in case of different delay, before and after the adjacent two sets of speaker distance between best 10 ~ 12m, maximum should not exceed 15m, otherwise the rear of the audience easily hear dual sound. Near the front of a group of speakers, their scope for sound should consider smaller, to overcome the acoustic feedback.

3. the application of sound columns
The use of sound in the venue, the entire column of the play at the venue's voice clarity, compared to even a slightly inclined to the sound column on certain height allows the venue before the sound even, thereby overcoming the voice always near a strong distance weak weakness, as the venue of the left and right sound, because the level of acoustic radiation angle is large, basically can keep even. If the halls is long, uses only one sound columns, you should put the sound column is longer, making it stronger orientation, as well as hang high, so that they can improve after weak before strong, and the sound column direction also reduces the reverberation interfere, the audience heard of direct sound relative to the halls of the reverberation time increases, thereby enhancing the audio clarity, the sound column of the play also makes sound feedback reduces; the direction from the sound column, along the upper and lower ends of the acoustic sounds the most light, direction is pronounced dead. If the high-hanging acoustic at the bottom of the column to the microphone, the sound of the feedback to the microphone in a significant reduction, reduced feedback amplifiers output can be larger, making full use of amplifying effect.
Sound column layout according to the AuditoriumThe case may be, in the layout, the sound column layout and orientation must be carefully debugging, to obtain satisfactory results.
4. Hall layout for instance
1) shows the position of the speakers at the movies
When the Auditorium of the wide, long, a high proportion of size standards-compliant, the speakers inclined to acoustic axis of the extension of the line access to the room of the number of rows of seats in the middle of the second part (approximately 2/3 the length of service), you can get good results. In addition, the relative position of each side speakers should be deflected to make them sound axis intersects the middle of the audience.
2) Stadium
In sports, often with sound reinforcement system to stand on the audience report venue competition, since the audience area and modeling, with a sound columns cannot be satisfactory sound level and the potential to reach ranges. Therefore, the need to integrate appropriate speaker is mounted on the playing field between all speakers around, to maintain the correct distance to the horizontal plane is uniform loudness.
Consider amplifying equipment required sound level should be the most crowded of noise levels. Although sometimes used the sound power is large enough to submerge the playground of the noise level, and therefore very noisy, power should be can't produce 80dB of sound level, the main problem is to select the device, it can meet in the distance and area within the required sound level requirements.
In recent years the sports ground also uses a centralized system. For example, a 6 million people in the stadium using centralized speakers set to get the sound pressure level 110dB, speaker set includes 16 only dog Horn and four low-frequency speaker with Horn, crossover point frequency selected in 350Hz.
2. sound reinforcement system acoustic feedback inhibition and microphone placement
1, acoustic feedback inhibition of
Sound reinforcement systems in the most difficult to overcome the difficulties is the feedback function.
1) reasons of occurrence of feedback
(1) speakers behind the microphone, the microphone in the loudspeaker's acoustic venue;
(2) speech sound from the microphone is too long (over 2m);
(3) Auditorium has a high noise level;
(4) in the Auditorium of the reverberation is too long, or the placement of the reflector spotlight in front of the microphone.
Acoustic feedback is affecting sound quality sound reinforcement system of one of the main factors, outdoor sound reinforcement system for acoustic feedback caused by direct sound, indoor sound amplifying system, in addition to the direct-to-noise-induced acoustic feedback, mixing sound field causes the more serious acoustic feedback.
2) Suppression of acoustic feedback
In order to improve the sound reinforcement system of effective power gain, measures must be taken to suppress acoustic feedback, sound reinforcement system inhibits the acoustic feedback of may of the following methods.
(1) choose the direction of the speaker is large enough, its frequency response is not affected by the interference of the resonant peaks;
(2) change the device's frequency response;
(3) change the speaker and microphone location;
(4) use the microphone with unidirectional characteristics;
(5) in the halls or noise source additional increase absorption treatment equipment;
(6) the use of decentralized speakers reproducing system, this will make the audience from the sound source is relatively recent, and therefore does not require high-power speaker, allowing the reverberation is maintained in a sound level is very low.
3) at the same time should meet the requirements of other
(1) sound reinforcement system at least 6dB of stability;
(2) the room sound field should, as far as possible, to shorten the reverberation time;
(3) to minimize the number of simultaneous use of the microphone. When do you need more than just the microphone at the same time, should control near the speakers (or speaker system) of power distribution.
2, rational arrangement of microphone
Accurate use of the microphone you can suppress acoustic feedback, improve audience area sound pressure level, and can improve the sound quality.
Microphone settings should satisfy the following requirements:
(1) the location of the microphone and speakers (or speaker system) spacing should be greater than the critical distance, and the speaker of the radiation outside the scope of point;
(2) when the room sound field is not uniform, the microphone should be avoided in the high part of the sound level;
(3) microphone away from the thyristor (SCR) sources of interference and its radiation.
For conference rooms, multifunctional Theatre, Stadium (Museum), and other different places should be necessary and reasonable to configure different types of microphones (including wireless microphone devices), and according to the most possible usage reserved microphone socket box.