echoA lot of how we refer to equalization has to
The reflection of sound from a surface suchdo with what a graph of the frequency re-
as a wall or a floor. Reverberation and echo aresponse would look like. A flat response (no
terms that can be used interchangeably, but inEQ) is a straight line; a peak looks like a hill, a
audio parlance a distinction is usually made:dip is a valley, a notch is a really skinny valley,
echo is considered to be a distinct, recogniz-and a shelf looks like a plateau (or a shelf).
able repetition (or series of repetitions) of aThe slope is the grade of the hill on the graph.
word, note, phrase or sound, whereas rever-Graphic equalizers have enough frequency
beration is a diffuse, continuously smoothslider controls to form a graph of the EQ right
decay of sound. Echo and reverberation can beon the front panel. Parametric EQs let you vary
added in sound mixing by sending the originalseveral EQ parameters at once. A filter is sim-
sound to an electronic (or electronic/acoustic)ply a form of equalizer that allows certain
system that mimics natural echoes, and thenfrequencies through unmolested while reduc-
some. The added echo is returned to the blending or eliminating other frequencies.
through additional mixer inputs. Highly echoicAside from the level controls, EQs are prob-
rooms are called live; rooms with very littleably the second most powerful controls on any
echo are called dead. A sound source withoutmixer (no, the power switch doesnOt count!).
added echo is dry; one with reverb or echofader
added is wet.Another name for an audio level control.
effects devicesToday, the term refers to a straight-line slide
External signal processors used to add re-control rather than a rotary control.
verb, delay, spatial or psychoacoustic effects tofamily of curves
an audio signal. An effects processor may beA composite graph showing on one chart
used as an insert processor (serial) on a par-several examples of possible EQ curves for a
ticular input or subgroup, or it may be used viagiven equalizer or equalizer section.
the aux send/return system(parallel). See alsofilter
echo, reverb.A simple equalizer designed to remove cer-
EINtain ranges of frequencies. A low-cut filter
Equivalent Input Noise. Specification that(also called a high-pass filter) reduces or
helps measure the Oquietness� of a gain stage byeliminates frequencies below its cutoff fre-
deriving the equivalent input noise voltage nec-quency. There are also high-cut (low-pass)
essary to obtain a given preamp's output noise.filters, bandpass filters, which cut both high
Typically ranges from �125 to �129.5 dBm.and low frequencies but leave a band of fre-
EQquencies in the middle untouched, and notch
See equalization.filters, which remove a narrow band but leave
EQ curvethe high and low frequencies alone.
A graph of the response of an equalizer,flanging
with frequency on the x (horizontal) axis andA term for phasing. Before digital delay ef-
amplitude (level) on the y (vertical) axis.fects units, phasing could be accomplished by
Equalizer types and effects are often namedplaying two tape machines in synchronization,
after the shape of the graphed response curve,then delaying one slightly by rubbing a finger
such as peak, dip, shelf, notch, knee and so on.on the reel flange. Get it?
equalizationFOH
Equalization (EQ) refers to purposefullyAn acronym for Front Of House. See house
changing the frequency response of a circuit,and main house speakers.
sometimes to correct for previous unequal re-frequency
sponse (hence the term, equalization), andThe number of times an event repeats itself
more often to add or subtract level at certainin a given period. Sound waves and the electri-
frequencies for sound enhancement, to removecal signals that represent sound waves in an
extraneous sounds, or to create completelyaudio circuit have repetitive patterns that range
new and different sounds.from a frequency of about 20 repetitions per
Bass and treble controls on your stereo aresecond to about 20,000 repetitions per second.
EQ; so are the units called parametrics andSound is the vibration or combination of vibra-
graphics and notch filters.tions in this range of 20 to 20,000 repetitions per
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ACEC
