Mackie CR1604 Owner's Manual

Glossary

of pro audio terms

Glossary

This Glossary contains brief definitions of
many of the audio and electronic terms and
acronyms used in discussions of sound mixing
and recording. Many of the terms have other
meanings or nuances or very rigorous technical
definitions, which we have sidestepped here
because we figure you already have a lot on
your mind.

If you’d like to get more information, there are
plenty of useful textbooks out there. We recom­mend the following titles:
by Glenn White,
Oppenheimer,
Glen Ballou,
bitt,

Pro Audio Reference

Sound Reinforcement Handbook

Tech Terms

Handbook for Sound Engineers

Mackie Mixer Book

The Audio Dictionary

by Peterson &

by

by Rudy Tru-

by Dennis Bohn, and

by Gary Davis.

A

aliasing

This is a type of distortion caused during the
analog-to-digital conversion process. If the fre­quency of the analog signal exceeds one-half
the sampling rate, spurious signals and harmon­ics not present on the original signal may be
created (see Nyquist Theorem). Careful design
and filtering before the sampling stage can
reduce this aliasing to a minimum.

assign

In sound mixers, assign means to switch or
route a signal to a particular signal path or com­bination of signal paths.

attenuate

To reduce or make quieter.

aux

ACRONYM

An acronym for A Contrived Reduction Of
Nomenclature Yielding Mnemonics

adiabatic

Literally, it means "not to pass through." In
describing the high-density foam used inside
the HR Series studio monitors, it means that
internal reflections within the cabinet are
absorbed by the foam. In physical terms, it
means the mechanical energy of the sound
wave is converted into heat energy.

A/D converter (ADC)

Analog-to-digital converter, a device that trans­forms incoming analog signals into digital
form.

AFL

An acronym for After Fade Listen, which is
another way of saying post-fader solo function.

Short for Auxiliary.

auxiliary

In sound mixers, supplemental equipment or
features that provide additional capabilities to
the basic system. Examples of auxiliary equip­ment include: serial processors (equalizers,
compressors, limiters, gates) and parallel pro­cessors (reverberation and delay).

aux send

A mixer bus output designed to send a signal to
an auxiliary processor or monitor system.

aux return

A mixer input (sometimes a pair of inputs) with
limited control capabilities, intended for bring­ing the output of an auxiliary processor or
other line-level source into the main mix bus.
Aux returns can sometimes be assigned to other
buses in the mixer.

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B

balanced input

An input consists of two leads, neither of which
is common to the circuit ground. This is a “dif­ferential pair”, where the signal consists of the

difference in voltage between the two leads. Bal-

anced input circuits can offer excellent rejec­tion of common-mode noise induced into the
line.

balanced output

In a classic balanced audio circuit, the output is
carried on two leads (high or + and low or -)
which are isolated from the circuit ground by
exactly the same impedance.

A symmetrical balanced output carries the same
signal at exactly the same level but of opposite
polarity with respect to ground.

A special case of a balanced output carries the
signal on only one lead, with the other lead
being at zero voltage with respect to ground,
but at the same impedance as the signal-carry­ing lead. This is sometimes called

anced

.

bandwidth

The band of frequencies that pass through a
device with a loss of less than 3 dB, expressed in
Hertz or in musical octaves. Also see Q.

impedance bal-

bus

An electrical connection common to three or
more circuits. In mixer design, a bus usually
carries signals from a number of inputs to a
mixing amplifier, just like a city bus carries peo­ple from a number of neighborhoods to their
jobs. It comes from the British “omnibus”.

C

Cannon

A manufacturer of electrical connectors who
first popularized the three-pin connector now
universally used for balanced microphone con­nections. In sound work, a Cannon connector
is taken to mean a Cannon XLR-3 connector or
any compatible connector. You can tell an
audio geezer because he refers to this connector
as “Cannon”. Today the term “XLR” is more
common.

cardioid

Heart-shaped. In sound work, cardioid refers to
the shape of the sensitivity vs. direction plot for
a particular style of directional microphone. A
cardioid mic rejects sound arriving from the
rear.

channel

bit

The smallest component of a digital word, rep­resented by either a one or a zero.

bridged mono

A mode of operation for a stereo amplifier that
routes a single input to both channels, but
inverts the signal on channel 2, thereby provid­ing twice the voltage of an individual output by
connecting the speaker between the two posi­tive output terminals (the negative output ter­minals are not used).

A functional path in an audio circuit: an input
channel, an output channel, a recording chan­nel, the left channel and so on.

channel strip

The physical realization of an audio channel on
the front panel of a mixer; usually a long, verti­cal strip of controls.

chorusing

A time-based effect available in some digital
delay effects units and reverbs. Chorusing
involves a number of moving delays and pitch
shifting, usually panned across a stereo field.

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Depending on how used, it can be lovely or
grotesque.

clipping

A form of severe audio distortion that results
from peaks of the audio signal attempting to
rise above the capabilities of the amplifier cir­cuit. Seen on an oscilloscope, the audio peaks
appear clipped off. To avoid clipping, reduce
the system gain in or before the gain stage in
which the clipping occurs. Also see headroom.

common mode

A signal which is referenced to the circuit com­mon point, usually chassis ground.

compressor

This is a dynamics processor used to smooth
out any large transient peaks in an audio signal
that might otherwise overload your system or
cause distortion. The amplitude threshold and
other parameters such as attack time, release
time, and tire pressure are adjustable.

cueing

In broadcast, stage and post-production work,
to “cue up” a sound source (a record, a sound
effect on a CD, a song on a tape) means to get
it ready for playback by making sure you are in
the right position on the “cue,” making sure the
level and EQ are all set properly. This requires a
special monitoring circuit that only the mixing
engineer hears. It does not go out on the air or
to the main mixing buses. This “cueing” circuit
is the same as pre-fader (PFL) solo on a Mackie
mixer, and often the terms are interchangeable.

D

D/A converter (DAC)

Digital-to-analog converter, a device that trans­forms incoming digital signals into analog
form.

damping

condenser

Another term for the electronic component
generally known as a capacitor. In audio, con­denser often refers to a type of microphone that
uses a capacitor as the sound pickup element.
Condenser microphones require electrical
power to run internal amplifiers and maintain
an electrical charge on the capacitor. They are
typically powered by internal batteries or
“phantom power” supplied by an external
source, such as a mixing console.

console

Another term for a sound mixer, usually a large
desk-like mixer.

crest factor

The ratio of the peak value to the RMS value.
Musical signals can have peaks many times
higher than the RMS value. The larger the tran­sient peaks, the larger the crest factor.

Damping factor is a number that represents the
ratio of the impedance of the load to the out­put impedance of the amplifier. In practical
terms, it is a measure of how well the amplifier
can control the movement of a speaker's cone.
The greater the damping factor, the better its
ability to control the cone's movement. A low
damping factor (high amplifier output imped­ance) allows a woofer to continue to move after
the signal stops, resulting in an indistinct and
mushy low frequency response. A high damp­ing factor (200 or above) provides excellent
control over low frequency woofers and pro­duces a tight, clean bass.

DAT

Digital Audio Tape is a recording/playback sys­tem where analog signals are converted to digi­tal form and stored on magnetic tape. It offers
all the benefits of digital audio including low
noise and wide dynamic range.

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DAW

Digital Audio Workstation is a dedicated
recording/editing software application and
hardware system, used for hard disk (non-lin­ear) random access recording and playback.
Many DAWs are used with personal computers
using Windows® or Macintosh® operating
systems, though some use their own proprietary
computers.

dB

See decibel.

dBA

Sound Pressure Level (SPL) measured with an
"A" weighting filter.

dBm

A unit of measurement of power in an electrical
circuit, expressed in decibels referenced to 1
milliwatt. The “m” in dBm stands for “milli­watt.” In a circuit with an impedance of 600
ohms, this reference (0 dBm) corresponds to a
signal voltage of 0.775 VRMS (because 0.775 V
across 600 ohms equals 1 mw).

dBu

A unit of measurement of audio signal voltage
in an electrical circuit, expressed in decibels ref­erenced to 0.775 VRMS into any impedance.
Commonly used to describe signal levels within
a modern audio system. Nobody is really sure if
“u” stands for anything.

dBv

Commonly used to describe signal levels in
consumer equipment. To convert dBV to dBu,
add 2.2 dB.

decibel (dB)

The dB is a ratio of quantities measured in sim­ilar terms using a logarithmic scale. Many audio
system parameters measure over such a large
range of values that the dB is used to simplify
the numbers. A ratio of 1000:1=60 dB. Since
dB is a unitless quantity, it doesn’t matter if it’s
volts or dollars. (just try asking the chief engi­neer for a 3 dB raise) When one of the terms in
the ratio is an agreed upon standard value such
as 1.23 V, 1 V or 1 mw, the ratio becomes an
absolute value, i.e., +4 dBu, -10 dBV or 0 dBm.

delay

In sound work, delay usually refers to an elec­tronic circuit or effects unit whose purpose it is
to delay the audio signal for some short period
of time. Delay can refer to one short repeat, a
series of repeats or the complex interactions of
delay used in chorusing or reverb. When
delayed signals are mixed back with the original
sound, a great number of audio effects can be
generated, including phasing and flanging, dou­bling, Haas precedence-effect panning, slap or
slapback, echo, regenerative echo, chorusing
and hall-like reverberation. Signal time delay is
central to many audio effects units.

detent

A point of slight physical resistance (a click­stop) in the travel of a knob or slide control.
Most knobs on Mackie mixers are detented to
indicate their unity gain or centered position.
It’s handy in the dark.

A unit of measurement equal to the dBu no
longer in use in the US, but sometimes still in
Great Britain. It was too easy to confuse a dBv
with a dBV, to which it is not equivalent.

dBV

A unit of measurement of audio signal voltage
in an electrical circuit, expressed in decibels ref­erenced to 1 VRMS across any impedance.

diffraction

The bending of sound waves around an obsta­cle (Huygens Principle). The longer the wave­length in comparison to the obstacle, the more
the wave will diffract around it.

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dipping

The opposite of peaking, of course, used in
audio to describe the shape of a frequency
response curve. A dip in an EQ curve looks like
a valley, or a dip. Dipping with an equalizer
reduces a range of frequencies. (See guacamole.)

dither

This is an interesting technique to reduce the
audibility of low level noise in a digital record­ing. Low level random noise is added to the
analog signal before the sampling stage, reduc­ing an effect called quantization error.

doubling

A delay effect, where the original signal is
mixed with a medium (20 to 50 ms) delayed
copy of itself. When used carefully, this effect
can simulate double-tracking (recording a voice
or instrument twice).

dynamic microphone

The class of microphones that generate electri­cal signals by the movement of a coil in a mag­netic field. Dynamic microphones are rugged,
relatively inexpensive, capable of very good per­formance and do not require external power.

dynamics processor

A type of processor that only affects the overall
amplitude level of the signal (sometimes as a
function of its frequency content), such as a
compressor, expander, limiter, or gate.

dynamic range

The range between the maximum and mini­mum sound levels that a sound system can han­dle. It is usually expressed in decibels as the
difference between the level at peak clipping
and the level of the noise floor.

dry

Usually means without reverberation, or with­out some other applied effect like delay or cho­rusing. Dry is not wet, i.e., totally unaffected.

DSP

Digital Signal Processing can accomplish the
same functions found in analog signal proces­sors, but performs them mathematically in the
digital domain, with more precision and accu­racy than its analog counterpart. Since DSP is a
software-based process, parameters and process­ing functions are easily changed and updated
by revising the software, rather than redesigning
the hardware. DSP can be found in an out­board effects device, such as a reverb or delay
unit, or it can be integrated into a DAW or dig­ital mixing console.

dual mono

A mode of operation for a stereo amplifier that
routes a single input to both channels, but still
allows independent level control over each
amplifier output.

E

echo

The reflection of sound from a surface such as a
wall or a floor. Reverberation and echo are
terms that are often used interchangeably, but
in audio parlance a distinction is usually made:
echo is considered to be a distinct, recognizable
repetition (or series of repetitions) of a word,
note, phrase or sound, whereas reverberation is
a diffuse, continuously smooth decay of sound.

Echo and reverberation can be added in sound
mixing by sending the original signal to an elec­tronic (or electronic/acoustic) system that mim­ics natural echoes, and then some. The added
echo is returned to the mix through additional
mixer inputs.

effects device or
effect processor

An external signal processor used to add reverb,
delay, spatial or psychoacoustic effects to an
audio signal. An effects processor may be used

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