Specifications

Typical sound system
Audio Systems Guide for
MEETING FACILITIES
8
CHAPTER THREE
THE SOUND SYSTEM
A basic sound reinforcement system consists of an
input device (microphone), a control device (mixer), an
amplification device (power amplifier), and an output
device (loudspeaker). This arrangement of components
is sometimes referred to as the audio chain: each device
is linked to the next in a specific order. The primary goal
of the sound system in meeting facility sound applications
is to deliver clear, intelligible speech to each meeting
participant. The overall design, and each component of
it, must be carefully thought out, properly installed, and
thoughtfully operated to accomplish this goal.
There are three levels of electrical signals in a sound
system: microphone level (a few thousandths of a volt), line
level (approximately one volt), and loudspeaker level (ten
volts or higher).
Sound waves are converted into an equivalent
electrical signal by the microphone. This microphone level
signal is amplified to line level and possibly combined with
signals from other microphones by the mixer. The power
amplifier then boosts the line level signal to loudspeaker
level to drive the loudspeakers, which convert the electrical
signal back into sound.
Electronic signal processors, such as equalizers, limiters
or time delays, are inserted into the audio chain, usually
between the mixer and the power amplifier, or often within
the mixer itself. These devices operate at line level and their
general function is to enhance the sound in some way or to
correct certain deficiencies in the sound sources.
In addition to feeding loudspeakers, the output of the
system may be sent simultaneously to recording devices or
even used for broadcast. It is also possible to deliver sound
to multiple rooms by using additional power amplifiers and
loudspeakers.
Finally, it is necessary to consider the room acoustics
as part of the sound system: acoustics act as a “signal
processor” that affects sound both before it is picked up
by the microphone and after it is produced by the
loudspeakers. Good acoustics may enhance the sound,
while poor acoustics may severely degrade it, usually beyond
the corrective capabilities of the equipment. In any case, the
role of room acoustics in sound system performance
cannot be ignored.
LOUDSPEAKER
BOUNDARY
MICROPHONE
VOCAL MICROPHONE
INSTRUMENT
MICROPHONE
MIXER PROCESSOR
AMPLIFIER