Large venue PA systems
For popular music concerts, a more powerful
and more complicated PA system is used to provide
live sound reproduction. In a concert setting, there are typically
two complete PA systems: the "main" system
and the "monitor" system. Each PA system
consists of microphones, a mixing board, sound processing equipment,
amplifiers, and speakers. There is disagreement over when to call
these audio systems Sound Reinforcement (SR) systems or a Public
Address (PA) systems. This distinction is important in
some regions or markets, while in other regions or markets the
terms are interchangeable.
" The "main"
system (also known as "Front of House", commonly abbreviated
FOH), which provides the amplified sound for the audience, will
typically use a number of powerful amplifiers driving a range
of large, heavy-duty loudspeakers including low-frequency speaker
cabinets called subwoofers, full-range speaker cabinets, and high-range
horns. A large club may use amplifiers to provide 1000 to 2000
watts of power to the "main" speakers; an outdoor concert may
use 10,000 or more watts.
" The "monitor"
system reproduces the sounds of the performance and directs
them towards the onstage performers (typically using wedge-shaped
monitor speaker cabinets), to help them to hear the instruments
and vocals. In British English, the monitor system is referred
to as the "fold back". The monitor system in a large club may
use amplifiers to provide 500 to 1000 watts of power to the "monitor"
speakers; at an outdoor concert, there may be several thousand
watts of power going to the monitor system.
At a concert in which live sound reproduction
is being used, sound engineers and technicians control the mixing
boards for the "main" and "monitor" systems, adjusting the tone,
levels, and overall volume of the performance.