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Quite frankly, the PA speakers’ placement plays a critical role in how your PA system would sound in a venue. Even if you are going to utilize innovative compressors, signal processors, and limiters, if you don’t position the PA speakers at the right spots, chances are, you will never get the optimum audio outputs from your PA speakers.
Aside from the speaker’s proper placement, the acoustics of the venue or space also plays a crucial role in determining the loudspeaker’s fidelity. Understanding these two essential factors, you can quickly maximize the performance of a loudspeaker.
Essential Factors to Consider When Setting Up Your PA Speakers
If you are playing the loudspeakers in a purpose-built venue, you won’t have many issues with the loudspeakers. Yet, if you are using the PA system outside or in a room not acoustically designed for such purpose, chances are, the loudspeakers will not achieve their optimal outputs. Thus, it will help to consider the following essential factors to maximize and optimize the use of the PA loudspeakers:
1) Consider Room Size
If you want to optimize the audience’s listening experience, you need to study the room’s design and size. Of course, you will encounter problematic rooms if you are engaged, for example, in large-scale tour productions. It is imperative you figure out if the place is problematic acoustically and correct the room’s impact on the sound system.
The venue or room’s size will directly affect the audio outputs produced by the loudspeakers. You may not be aware of these impacts. Yet, if you know how audio frequencies scatter after coming out of the loudspeakers, you will understand that various frequencies have various wavelengths.
The wavelength, for example, of a specific frequency, correlates with the room’s size. This factor creates standing waves wherein the original sound and reflected sound affect and reinforce each other. Sound level, of course, reduces its intensity as it moves away from its source. This reduction in the intensity is around 6dB per doubling of distance from the origin of the sound.
Moreover, it will be useful to note that the room’s reflected sound level appears to be relatively constant in the entire place or venue. A 50 Hz soundwave reproduces well in a small room. It will help compensate for the exaggerated presence of the 50 Hz soundwave by mixing well and utilizing the EQ well.
2) The Reflectivity of the Room
You should also consider the reflective nature of a room when positioning the PA system. The room acoustics, of course, can make or break your performance and muddle the audio signals. So, you need to figure out if the room is too live or too dead.
You can figure this out once you consider the walls and ceilings of the venue. Are they made of hard and reflective materials, or are they absorbent of soundwave? You can make proper adjustments depending on the nature of the room.
Some rooms reflect soundwaves, just like in the design of the cathedrals. Since these buildings were built when there were no loudspeakers yet, they were not acoustically designed for loudspeakers. Moreover, the standard PA system will not work well in a cathedral. So, you need to adjust with care the EQ and look for speakers’ proper placement to optimize their sound outputs.
If the room is so alive, the speaker’s sound and its reflection from the wall will be out of sync with each other. This fact may cause either reinforcement of the sound or cancellation of the sound.
Thus, if you find yourself setting up your PA system inside a very live room, it will be useful to position the speakers facing the room’s center. In this way, you can direct sound towards the middle of the room and away from the walls. You can also do an acoustic treatment on the room to dampen its reflective property.
3) Study the Room’s Construction
The thing about low-frequency waves is that they are powerful enough to make the walls and ceilings vibrate. Such vibration is called diaphragmatic action, which can lessen the low-end definition.
As much as possible, you want to match the driver size with that of the room because you don’t want to put so much energy in a place that can’t handle the said volume.
Moreover, you don’t want to put little energy in a room that can handle much audio output. Thus, it is crucial to consider the room’s construction and volume and match the speaker’s driver size to the room volume.
PA Speakers Placement Techniques & Guidelines
Once you have studied well the size, reflective nature, and construction of the room, you can then figure out the best placements for the PA speakers. When positioning the loudspeakers, it will be useful to consider the following factors:
Conventional speakers come with designs for projecting sound over a wide area with its cone-shaped diaphragm that moves vigorously back and forth to generate air pressure and soundwaves. These pressure waves allow people to hear the audio outputs from a wide area. The more power the speaker has, the larger the extent it can handle.
Speakers tend to project soundwaves in specific directions at various angles. This characteristic makes speakers directional. Experts categorize speaker patterns into two categories: short-throw and long-throw.
Long-throw speakers have narrow projection patterns at 20 degrees. These speakers are used in concerts and can target thousands of people at several hundreds of feet away. Club speakers, however, come with 60 by 40 degrees dispersion patterns or even more expansive. This means the high frequencies and midrange are projected at about this degree range. If you are out of that range, you would mostly hear the bass sounds and fail to hear the vocals.
So, if you are positioning a loudspeaker in a room, you need to direct the speakers toward the room’s important area carefully. If there are people at the sides of the stage, you also need to aim for an extra set of speakers to enable the side audience to hear the sound. It will be useful to note that if you can see the horn’s throat, you won’t hear the speaker’s sound.
2) Elevation or Height
Once you’ve zeroed in on the right spot for loudspeakers, you need to elevate the speaker cabinets. You need to do this to project the high frequencies above the front audience’s heads. You will need a pair of stands to elevate the loudspeakers.
Most PA cabinets come with a stand socket that lets you mount them. With the use of speaker stands, you can mount the horn over the heads of the audience. It will be advisable to get the speakers reasonably high with their horns around 8 feet above the floor. In doing, you leave the high frequencies unimpeded without beaming the sound directly at the front audience.
If you got separate subwoofers, you should keep them on the floor. Subwoofers, of course, work well at floor level. The thing is, if you elevate bass speakers, they lose half of their power.
3) Locations of Speakers
It will be useful to position the speakers in front of the performers or band to do away with the speaker-mic path. If the speakers face the performers, feedback will ensue. Stage mics come with a directional pattern that picks up sounds right in front of them. However, they reject sounds from the rear and sides.
The narrower the pickup pattern of a mic, the better it can minimize feedback. Because of the directional pickup patterns of stage mics, they can pick up sounds from the speakers if they face them. This position leads to feedback. Feedback can be hard on the ears of the audience or anyone hearing it. So, you need to ensure that it doesn’t occur during the show or performance.
To avoid feedback, you need to position the speakers away from the mics and performers. You should make them face the audience and point the microphones face in the opposite direction from the speaker. In so doing, you align the cancellation action of the microphone pickup pattern with that of the speaker back.
4) Area Coverage
The room’s area and its shape will usually determine how many speakers you would install in the place. They will also determine the placement of the speakers. So, before positioning those speakers, you need to bear in mind the speakers’ coverage pattern.
There are two coverage patterns that you should know—the horizontal and vertical coverage. So, if you have a large area, you should position the speakers in such a way that they can cover the whole area horizontally. The transition from one loudspeaker’s coverage area to another should be as smooth as possible to create a balanced response across the given space.
On the other hand, the vertical coverage pertains to the downward or upward coverage of the speakers. You should ensure that the vertical range complements the horizontal coverage.
Moreover, the listening plane of the audience should be aptly covered. You can angle the speakers downward, for example, to direct the speakers’ energy towards the audience and overcome the disruptive reflections of sounds. This placement is perfect for pole-mounted loudspeakers positioned on the floor or for loudspeakers mounted on a tripod.
During gigs and shows, you can’t completely control everything about your PA system and the place. What you can control is the placement of the speakers and the coverage of the speakers. You can control them because you can position the speakers at the right place after a thorough assessment of the venue.
Remember that you should maintain at a minimum level the reflected sound in the room or area. Then, beam as much direct sound as possible to the audience. Moreover, you should set the tone and other indicators at a constant level as possible. It will also help to redirect reflected sounds away from the mics.