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DC Event Lighting and Sound is a full-service provider for lighting, staging and sound solutions to the special event industry catering to the greater Washington D.C., Virginia and Maryland areas.

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Planning a corporate event? Our rental department has what you need to flawlessly execute your next corporate resentation, product launch and more. Inquire with DCELS about rojector rentals, pipe and base, uplighting, branded corporate gobo, and more.

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Power amplifiers

Power amplifiers boost a low-voltage level signal and provide electrical power to drive a loudspeaker. All speakers require power amplification of the low-level signal by an amplifier, including headphones. Most professional audio amplifiers also provide protection from overdriven signals, short circuits across the output, and excess temperature. A limiter is often used to protect loudspeakers and amplifiers from overload.

Like most sound reinforcement equipment products, professional amplifiers are designed to be mounted within standard 19-inch racks. Many power amplifiers feature internal fans to draw air across their heat sinks. Since they can generate a significant amount of heat, thermal dissipation is an important factor for operators to consider when mounting amplifiers into equipment racks. Active loudspeakers feature internally mounted amplifiers that have been selected by the manufacturer to be the best amplifier for use with the given loudspeaker.

In the 1970s and 1980s, most PA amplifiers were heavy Class AB amplifiers. In the late 1990s power amplifiers in PA applications have became lighter, smaller, more powerful and more efficient due to increasing use of switching power supplies and Class D amplifiers, which offer significant weight and space savings as well as increased efficiency. Installations in railroad stations, stadia and airports, their high efficiency allow them to run with minimal additional cooling and with higher rack densities compared to older amplifiers.

Digital loudspeaker management systems (DLMS) that combine digital crossover functions, compression, limiting, and other features in a single unit have become popular since their introduction. They are used to process the mix from the mixing console and route it to the various amplifiers in use. Systems may include several loudspeakers, each with its own output optimized for a specific range of frequencies (i.e. bass, midrange and treble). Bi, tri, or quad amplifying a sound reinforcement system with the aide of a DLMS results in a more efficient use of amplifier power by sending each amplifier only the frequencies appropriate for its respective loudspeaker. Most DLMS units that are designed for use by non-professionals have calibration and testing functions such as a pink noise generator coupled with a real-time analyzer to allow automated room equalization.

The amount of amplifier power used in a performance setting depends on a number of factors, such as the desired Sound Pressure Level of the performers, whether the venue is indoors or outdoors, and the presence of competing background noise. The following list gives a rough "rule of thumb" for the amount of amplifier power used in different settings:

  • "Small Vocal" system - About 500 watts
  • "Large Vocal" system - About 1,000 watts
  • "Small Club" system - About 9,000 watts
  • "Large Club" system - About 18,000 watts
  • "Small Stadium" system - About 28,000 watts