Ashly LIMITER/COMPRESSORS CL-100 Benutzerhandbuch - Seite 17

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ACTIVE
Electronic circuits which use devices such as
transistors and integrated circuits, and which
are capable of voltage and power gain as well
as loss. Circuits using only resistors, capacitors,
transformers, etc., are referred to as passive.
AMPLITUDE
The voltage level of a signal. May be measured
in volts
or decibels. Generally corresponds to
the volume or intensity of an audio signal.
ATTACK TIME
The amount of time that elapses before a
compressor) limiter begins to attenuate the
output level after threshold has been reached.
BALANCED
A 3-wire circuit arrangement in which two
conductors are designated as signal lines (+
and -), and the third is a shield and chassis
ground. The signal lines are of opposite polarity
at any given moment, and are of equal potential
with respect to ground. Balanced input
amplifiers are used in all Ashly products to
improve hum and noise rejection. Jumpering
signal minus (-) to ground provides an
unbalanced input.
BREATHING
A usually undesirable fluctuation of background
noise resulting from compressor action. (Also
called "Pumping.")
CENTER FREQUENCY
The frequency (or pitch) at which a filter is
most effective. In a parametric equalizer, it
refers to the frequency where a particular boost /
cut control has maximum effect.
COMPRESSOR
An amplifier which reduces its gain as its
input is increased beyond a predetermined
"threshold."
dB
A unit by which
audio levels can
be
COMPARED. Often thoroughly misunderstood
are the concepts that decibels represent the
level of a signal compared to some reference
level (15 dB cut means a certain level less
than a previous level — the absolute level of
the signal need not be known), and that decibels
are a logarithmic unit.
Some handy numbers to remember when
dealing with decibels:
+3 dB = Double Power
+6 dB = Double Amplitude, Quadruple
+6 dB = Power
+10 dB = 10X Power
+20 dB = 10X Amplitude, 100X Power
dBm
A unit of measurement in decibels where 0
dBm =a power level of 1 milliwatt into a 600
ohm load. Originally defined by the telephone
company
to measure line levels.
dBV
Decibel Volts, an update of the dBm definition
where 0 dBV = the same voltage level as 0
dBm, but with no regard to power or
impedance.
0 dBV = 0.778 Volts. This unit is
much more appropriate for modern audio
equipment with high impedance inputs and
low impedance outputs.
DISTORTION
Generally refers to ANY modification of an
audio signal which produces new frequencies
which were not in the original. Examples are
harmonic distortion, where a circuit adds
overtones to a fundamental signal, and
intermodulation or IM distortion, where two
frequencies beat together to produce sum and
difference frequencies.
EQUALIZATION
Modification
of the frequency response of an
audio
system for either corrective
or
enhancement purposes.
FEEDBACK
Generally refers to any process where an output
is in some form routed back to an input to
establish a loop. Negative feedback tends to
be be self stabilizing, while positive feedback
causes instability.
FREQUENCY
The repetition
rate of a waveform. Frequency
is measured in Hertz. One cycle per second
(cps) is one Hertz (Hz). The higher
a note ona
musical scale, the higher its frequency.
FREQUENCY
RESPONSE
Refers to relative gain and loss at various
frequencies across the audio band. May be
illustrated by a graph called a frequency
response plot, usually graphing decibels vs.
hertz
or octaves.
GAIN REDUCTION
The amount (expressed
in dB) by which a
compressor |limiter'soutput
has been reduced
ia fost with respect to its uncompressed
vel
HEADROOM
Refers
to the increase in level above normal
operating level that can be obtained without
clipping. Usually expressed in dB.
IMPEDANCE
Essentially the AC equivalent
of resistance.
It describes
the drive capability of an output,
or the amount of drive required for an input
at any given signal level.
KHz
Kilohertz. 1,000 Hertz.
LEVEL
The magnitude of a signal, expressed in
decibels
or volts.
LINE LEVEL
Meaning "somewhere around OdBV" as
opposed to MIC level of around -40dBV.
LIMITER
An amplifier which reduces its gain as its
input is increased beyond a predetermined
threshold.
Usually used to protect audio
systems against sudden, high level signals,
and possible overload.
OCTAVE
A logarithmic unit to compare frequencies.
+1 Octave means double frequency, -1 Octave
means half frequency.
OHM
The unit of electrical resistance or impedance.
PREAMPLIFIER
The first stage of amplification, designed to
boost very low level signals to line level.
RATIO
The relationship between change in input
level and resultant change in output level.
RELEASE TIME
The time required for a compressor
| limiter
to restore system gain to normal after the
input signal has fallen below threshold.
SATURATION
The point at which the magnetic storage
capability of a piece of recording tape is
exceeded.
SIBILANCE
The distortion caused by loud high frequency
signals, such as the 'Ssss...'soundsin
human
speech.
THRESHOLD
The level above which a compressor
/ limiter
begins
to reduce gain.
TRANSIENT
A sudden burst of energy in an audio signal,
such
as a breath blast
in a microphone, the
sound of a snare drum, or a deep scratch in
a record. Transients frequently reach peak
levels of 10 to. 30dB above standard operating
level, and may cause distortion oreven damage
to equipment.
UNITY GAIN
Output
level = Input level.