Yamaha mLAN Mixer Owner's Manual page 33

COMPANDER (HARD & SOFT)
The hard (H) and soft (S) companders comprise of compressor, expander, and limiter. The limiter prevents
output signals from exceeding 0 dB. The compressor compresses signals that exceed the threshold level. The
expander attenuates signals below the threshold and width. The soft compander has an expansion ratio of
1.5:1, while the hard compander has an expansion ratio of 5:1. The following two graphs show typical com-
pander curves. The one on the left shows the hard compander. The one on the right, the soft compander.
+20
+10
0
–10
–20
–30
–40
–50
–60
–70
–70 –60 –50
Parameter
THRESHOLD
–54 dB to 0 dB (55 steps)
OUT GAIN
–18 dB to 0 dB (0.5 dB steps)
WIDTH
1 dB–90 dB (1 dB steps)
ATTACK
0–120 ms (1 ms steps)
5 ms–42.3 s (fs = 48 kHz)
RELEASE
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 (15 steps)
THRESHOLD
—This determines the input signal level at which compression and expansion are
applied. Signals at a level below the sum of the threshold and width are attenuated by the expander. Sig-
nals at and above the threshold level are compressed by the amount specified using the Ratio parameter.
The trigger signal is sourced using the KEY IN parameter.
OUT GAIN
—This sets the compander's output signal level. It can be used to compensate for the over-
all level change caused by the compression and expansion processes.
WIDTH
—This determines how far below the threshold level expansion is applied. The expander is
essentially turned off when the width is set to 90 dB.
ATTACK
—This determines how soon the signal is compressed and expanded once the compander has
been triggered. With a fast attack time, the signal is companded almost immediately. With a slow attack
time, however, the initial transient of a sound passes through unaffected. Attack times from 1 to 5 milli-
seconds are a good place to start.
RELEASE
—This determines how soon the compressor and expander return to their normal gains once
the trigger signal level drops below the threshold. If the release time is too short, the gain will recover
too quickly causing level pumping (i.e., noticeable gain fluctuations). If it is set too long, the compressor
may not have time to recover before the next high level signal appears, and it will be compressed incor-
rectly. Release times from 0.1 to 0.5 seconds are a good place to start.
RATIO
—This determines the amount of compression. That is, the change in output signal level rela-
tive to change in input signal level. For a 2:1 ratio, for example, a 10 dB change in input level (above the
threshold) results in a 5 dB change in output level. For a 5:1 ratio, a 10 dB change in input level (above
the threshold) results in a 2 dB change in output level. The expander ratios are fixed: 1.5:1 for the soft
compander (S) and 5:1 for the hard compander (H).
Width
Threshold
–40 –30 –20 –10 0 +10 +20
Input Level (dB)
Hard Compander
+20
+10
Width
0
–10
–20
–30
–40
–50
–60
–70
–70 –60 –50 –40
Soft Compander
Range
33
Threshold
–30 –20 –10 0 +10 +20
Input Level (dB)