Mackie 8-BUS Series, Руководство пользователя

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D i g i t a l 8 • B u s
Glossary
A-2
D/A converter
Digital-to-analog converter, a device that
transforms incoming digital signals into analog
form.
DAT
Digital Audio Tape is a recording/playback
system in which 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.
DAW (digital audio workstation)
A dedicated recording/editing software (ap-
plication) and hardware system, used for hard
disk (non-linear) random access playback and
recording. Many DAWs are used with personal
computers using Windows
® 95 or Macintosh ®
operating systems, though some use their own
proprietary computers.
dB
Dog Biscuit, see also decibel .
dBu
A unit of measurement of audio signal level
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.
dBv
A unit of measurement equal to the dBu but
no longer in use. 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 level
in an electrical circuit, expressed in decibels
referenced to 1 VRMS across any impedance.
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 1000V:1V is
equal to 60 dB. When one of the terms in the
ratio is an agreed-upon standard value such as
0.775V, 1V or 1mw, the ratio becomes an abso-
lute 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 pe-
riod of time. Delay can refer to one short
repeat, a series of repeats, or the complex in-
teractions 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 flang-
ing, doubling, Haas-effect positioning, slap or
slapback, echo, regenerative echo, chorusing,
and hall-like reverberation. Signal time delay is
central to many audio effects units.
dither
This is an interesting technique used to re-
duce low-level distortion by adding random
noise to the analog signal before the sampling
stage. Adding dither decorrelates the quantiza-
tion error from the signal level, allowing the
digital system to encode amplitudes smaller
than the least significant bit.
DSP
Abbreviation for digital signal processing.
DSP 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 counter-
part. 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.
dry
Usually means without reverberation, or
without some other applied effect like delay or
chorusing. Dry is not wet, i.e., totally
unaffected.
dynamic range
The range between the maximum and mini-
mum 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.
dynamics processor
Dynamics processors are used to correct or
control signal levels. The Digital 8•Bus pro-
vides gate and compressor dynamic processing
for each of the first 48 channels.
echo
.......
echo
........echo
The reflection of sound from a surface such
as a wall or a floor. Reverberation and echo are
terms that can be 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 sound to
an electronic (or electronic/acoustic) system
that mimics natural echoes and then some. The
added echo is returned to the blend through
additional mixer inputs. Highly echoic rooms
are called live; rooms with very little echo are
called dead. A sound source without added
echo or reverb is dry; one with reverb or echo
added is wet.