What is a Stage Monitor System?

The stage monitor system is a specialized
sound reinforcement system
that operates independently of the
house sound system. Like the house
system, it consists of a console, equalizers
(and, occasionally, other signal
processors), power amplifiers and
loudspeakers. Since the monitor
system is used to help the musicians
onstage hear their performance, the
loudspeakers are pointed toward the
stage rather than into the house.
The primary difference is that the
monitor console has many separate
output channels, each driving a separate
amplifier and loudspeaker chain
with a different mix, whereas house
sound systems are monophonic or
stereophonic (even if they do use a split
stack up front and a few surround or
fill speakers, many systems are mono).
Each monitor output mix is assigned
to one or a few of the performers, and
the mix that each hears is tailored to
his or her particular needs. In order to
stay on key and on cue, for example,
the lead vocalist needs mostly to hear
the background vocalists, along with
perhaps a bit of the keyboard and
guitar. Similarly, the bass player needs
to hear the kick drum, and the drummer
needs to hear the bass. The guitar
player needs to hear both, while the
keyboardist might need to hear the
lead vocal and the guitar.
For this reason, monitor mixing
consoles usually have eight or more
output busses, and are designed for
flexibility in assigning the inputs