Expander - RME Audio ADI-96 PRO User Manual

9.4 Expander

Function
Level dependent level reduction, each channel with adjustable threshold (-30 dB to -110 dB),
release (0.1 s to 25.5 s), ratio (1.2 to 5.0) and attack time (Fast 1 ms or Slow 25 ms).
Application
Allows broadband suppression of noise, removal of noise and hum in low level parts or be-
tween tracks, and de-compression of highly compressed material.
Settings
Place the cursor in the Overview window on EXP and press Enter.
Menu
Options
Adjustable are:
Threshold -30 dB to -110 dB. When the overall level is lower than this value the Expander
begins to reduce the level.
Ratio 1.2 to 5.0. Defines the ratio between original and reduced level.
Release 0.1 s to 25.5 s. Defines the time needed to reach 20 dB level reduction after the
last overall level exceeded the threshold value.
Attack Fast (1 ms) or Slow (25 ms).
Link Left/Right. Avoids pan shifts by combined controlling of both channels.
Typical Settings
As opposed to a Noisegate an Expander does not switch off audio when the Threshold is no
longer reached. Instead the level is lowered smoothly according to the chosen ratio. A ratio of
1.2:1 equals nearly no change, because a change in input level of 10 dB leads to a 12 dB chan-
ge in output level (only 2 dB difference). Typical Ratio values are 2 to 3 at a Release of 2 s.
That way, music can be faded in and out without heavy side effects. Noise between tracks can
be reduced easily.
The Threshold of the Expander has a strong relationship with the audio material and the noise
in it. LPs often require a Threshold of -30 dB (plus Attack Slow, see chapter 9.8), while re-
cordings from hi-quality sources often only need values around -75 dB. At values of -100 dB
the dynamic range of the ADI-96 PRO can be increased.
With more extreme settings like Ratio 5:1 and Release 0.1 s the Expander operates like a Noi-
segate. With these settings it is possible for example to isolate percussive instruments from
environmental noise.
The settings Ratio 1.5:1 and a Release of around 0.5 s allows to de-compress signals which
were too strong compressed before. This will result in a more natural, open sound, but the origi-
nal can't be recovered completely.
User's Guide ADI-96 PRO © RME
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