ENGLISH
7
Release
RELEASE determines how quickly compression is removed
once the level of the source signal has fallen below the
Threshold. When in the anticlockwise position, the
compression releases very quickly, which may be
appropriate on rapidly varying signals to avoid compressing
the beats that follow, but can result in excessive distortion
on more sustained material. Clockwise rotation increases
the release time, giving a smoother effect, but which at the
same time may result in transients causing audible
“pumping”.
Auto Release
The AUTO RELEASE switch makes the release time
automatic, substituting an adaptive attack/release circuit,
which essentially varies the release rate to suit the dynamics
of the signal. This enables the use of fast attack times
without any “pumping” type artefacts, especially effective on
complex programme material.
The release rate is probably the most important variable
when recording rock music, since it controls loudness.
Loudness is determined by the maintenance of high mean
levels: compression increases the proportion of high-level
signal content, and as the diagram shows, the faster the unit
releases, the more low-level signal is brought to a higher
level. Therefore, the faster the release rate, the higher the
perceived loudness of the recording.
Blend
This switch, when engaged, mixes the compressed and
uncompressed signals, allowing more of the dynamics of the
original source to be maintained. This simple operation
simulates the common producer’s practice of mixing
compressed and uncompressed signals on two separate
channels of a mixing console.
The unique 'blend' switch on the ISA 220 recombines the
direct unprocessed signal with the post-compression signal
at the gain make-up stage. The direct (uncompressed) signal
is lowered by 6dB to compensate for possible overload. As
the make-up gain is raised, quieter sections of the
compressed audio signal increase in value, while transients
pass without being processed. The result is that the
required reduction in the dynamic range of the signal is
achieved without an overly 'squashed' sound being audible.
Note: when used pre-EQ (COMP PRE EQ switch
illuminated) it may be possible to overload the EQ circuit
when using 'blend.' Hence best results will be obtained with
a post-EQ setting (COMP PRE EQ switch not illuminated.)
Make Up
Compression results in an overall reduction in level. The
MAKE UP control allows you to restore the signal volume
back to the original level. The gain reduction meter is useful
for determining how much make up gain needs to be
applied.
De-esser
The DE-ESSER is based on optical technology, letting you
remove excessive sibilance from a vocal performance (if
“ess” sounds are over-emphasised).
De-Ess In
Press in to activate the de-esser.
Threshold
THRESHOLD determines how much de-essing is being
applied to the selected frequency. The lower the threshold
(control anticlockwise), the more de-essing is applied.
Freq
This control selects a frequency to remove between 2k2Hz
and 9k2Hz.
De-Ess Listen
Press to allow isolated monitoring of only those signals
which will trigger activation of the de-esser, rather than
hearing the overall effect in a complex signal. When the de-
esser has been set up as desired the switch should be
released.
