User Manual

Compressor Types
13
EXPANDER
An expander is similar to a compressor except that it
works on signals below the threshold level. By reducing
signals below the threshold level, the expander attenu-
ates low-level noise, effectively increasing the dynamic
range and improving the signal-to-noise performance.
An expander set to an infinite ratio (i.e., ∞:1) is essen-
tially a gate.
The following two graphs show typical expander curves.
The one on the left shows an expander with an expan-
sion ratio of 2:1 and a hard knee setting. The one on the
right shows an expander with an expansion ratio of 2:1
and a soft knee setting of 5.
THRESHOLD—This determines the level of input signal
required to trigger the expander. Signals above the
threshold pass through the expander unaffected. Signals
at and below the threshold level are attenuated by the
amount specified using the Ratio parameter. The trigger
signal is sourced using the KEY IN parameter.
OUT GAIN—This sets the expander’s output signal level,
and can be used to compensate for the overall level
change caused by the expansion process.
KNEE—This determines how expansion is applied at the
threshold point. When set to hard, expansion at the
specified ratio is applied as soon as the input signal level
falls below the specified threshold. For knee settings
from 1 to 5, however, expansion is applied gradually as
the signal falls below the specified threshold, creating a
more natural sound.
ATTACK – Specify the time over which the expander will
return to the normal gain after the trigger signal exceeds
the threshold. If the attack time is too short, the gain will
return suddenly, causing the sound to “jump out.” (The
gain change will be obtrusive.) However if the attack is
too long, the next signal will be input before the gain has
returned, causing inappropriate expansion. When set-
ting the attack time, it is a good idea to start with a value
in the range of 1–5 milliseconds.
RELEASE – Specify the time over which the signal is
expanded from when the expander is triggered. If the
release time is short, the signal will be expanded almost
instantly. If the release time is long, the release portion of
the sound will not be expanded. When setting the release
time, it is a good idea to start with a value in the range of
0.1–0.5 seconds.
–70
–60
–50
–40
–30
–20
–10
0
+10
+20
–70 –60 –50 –40 –30 –20 –10 0 +10 +20
Input Level (dB)
Output Level (dB)
Threshold = –10dB
Knee = Hard
Expansion ratio = 2:1
–70
–60
–50
–40
–30
–20
–10
0
+10
+20
–70 –60 –50 –40 –30 –20 –10 0 +10 +20
Input Level (dB)
Output Level (dB)
Threshold = –10dB
Knee = SOFT 5
Expansion ratio = 2:1
Parameter Range
THRESHOLD –54 dB to 0 dB (1 dB steps)
OUT GAIN ±0.0 dB to +18.0 dB (0.5 dB steps)
KNEE
HARD, SOFT 1, SOFT 2, SOFT 3,
SOFT 4, SOFT 5
ATTACK 0–120 ms (1 ms steps)
RELEASE
5 ms–42.3 s (fs = 48 kHz)
6 ms–46 s (fs = 44.1 kHz)
RATIO
1:1, 1.1:1, 1.3:1, 1.5:1, 1.7:1, 2:1,
2.5:1, 3:1, 3.5:1, 4:1, 5:1, 6:1, 8:1,
10:1, 20:1, ∞:1 (16 points)
INPUT FILTER
HPF/LPF
HPF (high-pass filter) or
LPF (low-pass filter)
INPUT FILTER
ON/OFF
ON or OFF
INPUT FILTER
FREQUENCY
20 Hz–20 kHz (121 steps)