Whether providing sound support for a high school musical, orchestra or live music venue, filling a large space with sound can be a challenge. The goal is not merely whether performers can be heard, but insuring that what the audience hears is what the performers intend. An effective sound reinforcement configuration will allow as many of the audience members to hear the same sound quality as possible. To achieve this, you need to have a basic understanding of sound design for large venues.
Take stock of the room. Choices for sound equipment depend not on size alone, but the interior components of the auditorium. Upholstered seats absorb acoustical energy, as do drapes, curtains and other kinds of materials. A highly absorptive smaller auditorium may require more amplification than a large reflective one. Surfaces that reflect sound include cement or wood floors as well as metal surfaces.
Choose amplification and speakers appropriate to room size. Small theatres may require smaller integrated speaker systems that include low, mid and high frequency drivers. Likewise, these speakers will require less expensive amplifiers that reproduce the full spectrum of acoustical energy. Very Large auditoriums may require component speakers where the bass (woofers), midrange and high end speakers are each in their own enclosures. These speaker systems require companion amplifiers that likewise divide the audio spectrum into distinct regions using components referred to as crossovers. Depending on the size of your auditorium, your amplification system may need to produce several hundred, or several thousand watts of power to drive the speakers so that the entire space is filled with sound.
Include equalization components. An equalizer can add to or diminish specific frequencies in the audio spectrum to compensate for the acoustical properties of the auditorium. Use of equalizers can also reduce feedback from microphones. Equalizers may exist as stand-alone devices, or integrated into the sound mixing console.
Choose a mixing console that affords maximum flexibility for the number of audio sources required. If live performance is your goal, consider performers also need to hear themselves. Speakers or headphones available on stage are referred to as monitors. Your mixer should support ample monitor outputs to performers. Monitors also require their own amplifiers. Your choice of monitor again depends on the stage size and acoustical properties of the auditorium. Some venues may sound better if each performer has their own headphones instead of an open speaker that could reflect off the back of the stage towards the audience. Headphones, however, are not always practical for certain applications
Select microphones that are highly directional. That is, they do not pick up ambient sounds from the room. Auditoriums may have unpredictable reflective surfaces that cause feedback, so microphones should be placed as close to the sound source as possible.