Sound Should Always Be Directed Towards the Audience
An important rule when it comes to PA systems is to ensure that the sound is always directed towards the audience, and nowhere else. But this often doesn’t happen for whatever reason.
The most important rule in the world of loudspeakers is to point them directly at the audience. It’s also important to think about how much sound is being ricocheted off the walls and ceiling. The audience members will absorb just about all the sound that is directed at them; sound won’t necessarily bounce off them towards other parts of the venue. But walls and ceilings are much more reflective in nature; therefore, the more sound is directed at them, the more sound will bounce off them and distort sound.
EAW CLA37 column loudspeakers use seven 3–inch drive units to cover 120° horizontal x 30° vertical, thereby helping to tightly control the vertical dispersion. It’s perfect for speech reinforcement in spacious environments if many units are distributed to the audience.
When speech content is of main importance, the best solution would be to make use of a variety of small loudspeakers and keep them close to the audience members. However, this option isn’t adequate for a musical performance because we expect the sound to come from the stage, which is typically where the performers are. If the sound came from a small speaker sitting at a short distance away up and to the side, it would conflict with the visual and the audio.
Since having many small speakers doesn't work for musical performances, it’s necessary for the sound to seem as though it is coming from the stage as much as possible. For this reason, it’s best to have the loudspeakers positioned at the sides of the stage. Yet there are still possible issues with this.
For starters, directivity can be a problem. Loudspeakers naturally have a directional response, so anyone that’s sitting right in front of the loudspeaker will hear a rather flat frequency response. On the other hand, those who are sitting further to the side will hear less high frequencies, making the sound seem very dull. Big stereo systems will suffer because they spray the walls and ceiling with low frequencies that reflect too much, and only a few people in the audience will be able to hear sound with well-balanced frequencies.
Another issue is the lack of directional control. Since most of the sound is spread out a great deal past the audience, energy is lost. Sound sources get quieter as they become more distant because of the energy that is spread out. Distance can ruin everything; members of the audience that are sitting far away from the loudspeakers will hear a distant and quiet sound, while a person close to the speakers are experiencing sound that is far too loud.
Setting Up Line Arrays
PA systems need to be assembled at stage level, with the entire system hoisted up. Luckily this can be done without having to touch it through the use of remote controls. Line arrays can be set up by only a couple of people, in fact. However, when any component needs to be airborne at any point, much more responsibility is warranted. The most dangerous part messig up the system is when the equipment is at stage level.
When setting up a PA system, you need to make sure that you position it right. The height and horizontal angling needs to be right, and the array should take up a J–shaped curve in order for sound to be distributed evenly from the front to the back. Software can simplify this process, which can be used to calculate all parameters.