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Gate
When the GATE switch is pressed the Parametric EQ is inserted in
the Gate sidechain for accurate drum gating. This selection is
cancelled if PARAM EQ IN or COMP is pressed.
SHELVING EQ
High and Low frequency
shelving sections are available,
each with continuously
variable boost/cut with centre
detent, and a six position
rotary switch for selection of
rolloff frequency.
Shelving EQ In
Press in to switch all the
Shelving EQ into the signal
path. This selection is
cancelled if GATE or COMP is
pressed.
Comp
When the COMP switch is pressed the Shelving EQ is inserted in
the Compressor sidechain for frequency-selective compression.
This selection is cancelled if SHELVING EQ IN or GATE is pressed.
Gate
When the GATE switch is pressed the Parametric EQ is inserted in
the Gate sidechain for accurate drum gating. This selection is
cancelled if SHELVING EQ IN or COMP is pressed.
Compressor
Comp In
Press COMP IN to switch the compressor into the signal path.
Note that the VU meter can be selected to display the compressor
gain reduction (see Metering section).
Ratio
The RATIO control determines
the rate at which compression
is applied to the signal with
increasing input, and is the ratio
of change in input level
compared to change in output
level. The control gives a range
of 1.5 to 10. Higher Ratio
settings will produce more noticeable compression, so for the least
obtrusive result, the Ratio should be set at the minimum necessary
for the application. For example, using low Threshold and low
Ratio will produce less subjectively noticeable effect than a high
threshold and high ratio, even though the total amount of
compression may be the same.
Threshold
THRESHOLD determines the
level at which compression
begins, with a range -28dB to
+12dB. The lower the
Threshold, the more the signal
is compressed. Setting a higher
Threshold allows quieter
passages in the music or
speech to remain unaffected; only passages that exceed the
Threshold will be compressed.
Comp Listen
Press to allow audio monitoring of the compressor sidechain to
assist accurate frequency adjustment during setup. The LISTEN
LED beside the VU meter illuminates to show that ‘Listen’ mode is
active.
Attack
ATTACK determines how quickly compression is applied once the
level of the source signal has risen above the Threshold. When
turned anticlockwise the response is very fast, which tends to make
the compressor react to the peak levels of the signal. This is
sometimes desirable, but can cause unwanted “pumping” of
steadier low level components of the signal by short transients. A
slower attack will cause the compressor to ignore short transients
and respond more to the average loudness of the signal; however
this may seem to increase relative volume of the transients.
Release
RELEASE determines how quickly compression is removed once
the level of the source signal has fallen below the Threshold. When
in the anticlockwise position, the compression releases very
quickly, which may be appropriate on rapidly varying signals to
avoid compressing the beats that follow, but can result in excessive
distortion on more sustained material. Clockwise rotation
increases the release time, giving a smoother effect, but which at
the same time may result in transients causing audible “pumping”.
Rotation fully clockwise switches release to AUTO, substituting an
adaptive attack/release circuit which essentially varies the release
rate to suit the dynamics of the signal. This enables the use of fast
attack times without any “pumping” type artefacts, especially
effective on complex programme material.
The release rate is probably the most important variable when
recording rock music, since it controls loudness.
Loudness is determined
by the maintenance of
high mean levels:
compression increases
the proportion of high-
level signal content, and
as the diagram shows, the
faster the unit releases,
the more low-level signal
is brought to a higher
level. Therefore, the
faster the release rate,
the higher the perceived
loudness of the
recording.
Ext Key
Pressing EXT KEY switches control of the compressor to an
external signal on a rear panel jack socket.
Make Up
Compression results in an overall reduction in level. The MAKE UP
control allows you to restore the signal volume back to the original
level.
