Yamaha Professional Audio Workstation AW4416 - Manual (Page 442)

Appendix
Appendix–
26
— Reference Guide
Expander
An expander is another form of automatic level control. By attenuating the
signal below the threshold, the expander reduces low-level noise and effec-
tively increases the dynamic range of the recorded material.
Expander (EXP) parameters:
Threshold determines the level of input signal required to trigger the
expander. Signals above the threshold pass through unaffected. Signals at
and below the threshold level are attenuated by the amount specified using
the Ratio parameter. The trigger signal is determined using the KEY IN
parameter.
Ratio controls the amount of expansion—the change in output signal level
relative to change in input signal level. With a 1:2 ratio, for example, a 5 dB
change in input level (below the threshold) results in a 10 dB change in out-
put level. For a 1:5 ratio, a 2 dB change in input level (below the threshold)
results in a 10 dB change in output level.
Attack controls how soon the signal is expanded once the expander has
been triggered. With a fast attack time, the signal is expanded almost imme-
diately. With a slow attack time, the initial transient of a sound passes
through unaffected.
Out Gain sets the expander’s output signal level.
Knee sets the transition of the signal at the threshold. With a hard knee, the
transition between unexpanded and expanded signal is immediate. With
the softest knee, knee5, the transition starts before the signal reaches the
threshold and gradually ends above the threshold.
Release determines how soon the expander returns to its normal gain once
the trigger signal level drops below the threshold.
Parameter Value
Threshold (dB) –54 to 0 (55 points)
Ratio 1.0, 1.1, 1.3, 1.5, 1.7, 2.0, 2.5, 3.0, 3.5, 4.0, 5.0, 6.0, 8.0,
10, 20,
∞
(16 points)
Attack (ms) 0 to 120 (121 points)
Outgain (dB) 0 to +18 (36 points)
Knee hard,1,2,3,4,5 (6 points)
Release (ms) 5 ms to 42.3 sec
*1
, 6 ms to 46.0 sec
*2
,
8 ms to 63.4 sec
*3
(160 points)
*1. These values are obtained when the sampling frequency is 48kHz.
*2. These values are obtained when the sampling frequency is 44.1 kHz.
*3. These values are obtained when the sampling frequency is 32 kHz
-70
-60
-50
-40
-30
-20
-10
0
+10
+20
-70 -60 -50 -40 -30 -20 -10 0 +10 +20
Input Level
Output Level
dB
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
Output Level
dB
dB
Threshold = -20dB
Knee = knee5
Expansion ratio = 2:1