Input Mode - E-Mu 404 Owner's Manual

5 - Effects
Core Effects Descriptions
The diagram above shows the gain curves using a Threshold at -30dB and a range of
negative compression ratios.
At just past 1:INFINITE, the setting of 1:-100 causes input signals approaching 0dB to
be only slightly decreased below -30dB. In contrast, the compression ratio of 1:-1 causes
a 2dB gain reduction for each 1dB of additional input signal level, resulting in an output
signal level that is folded down over the Threshold.

Input Mode

The Input Mode parameter allows the compressor signal path and sidechain to be
driven in common or by separate inputs. This is a feature of many compressors and is
useful for a range of applications and special effects.
By default, the Input Mode of the compressor is Stereo. In this mode the two
independent left and right signal paths are gain controlled by a parallel sidechain path
common to both inputs that contains the compressor's level detector. This single level
detector works on the higher of the two input signal levels, so that signal peaks are
properly compressed and no L/R image shift results from compression operations.
When the Input Mode is set to L In/R Sidechain, the signal path is fed exclusively from
the left channel and the sidechain is fed exclusively from the right channel. This allows
dynamics control between two completely independent signals. In this mode both the
compressor's left and right outputs are fed by the mono signal from the left input
channel's signal path.
Splitting the signal path and sidechain makes possible applications where the two
signals may be completely unrelated, such as ducking. Other split-sidechain applica-
tions result from situations where a stereo input signal has had different processing
applied between left and right channels. One example would be to place a stereo
equalizer ahead of the compressor in order to implement a version of de-essing or "de-
booming". See page 90.
Create a Ducker
To create a ducker, in which a background signal's level is reduced in the presence of a
foreground signal, first set the Input Mode parameter to L In/R Sidechain. Then send
feeds from the background signal to the left input, and from the foreground signal to
the right side input. Set the Ratio parameter to -1:1 (or lower for less background
reduction), and dial in a low Threshold such as -50, so any foreground signal above -
50dB will cause gain reduction in the background signal. This technique works best
with slow Attack and Release times — use a liberal amount of Compression Lookahead
to keep the background from masking the beginning of foreground sounds.
Creating a Ducker
Ducker
L
L
Background Signal
Gain
Out
Pan -90 (L)
Cell
Stereo Strip
R
R
Foreground Signal
Sidechain
Pan +90 (R)
E-MU Digital Audio System 87