Adjusting The Limiter; Sidechain Filter; Sidechain Applications; Frequency-Dependent Dynamics - IMG STAGELINE MCL-204 Mode D'emploi

ATTACK (18) and the release time with the
control RELEASE (20) . Figure 10 illustrates the
effect the two controls will have on the signal
reduction .
Fig. 10 Controls ATTACK and RELEASE
Hints concerning adjustment:
a . When processing voices, a relatively long
attack time will be required so that the
voice will not lose power . In this case, high
level peaks will only occur after long vow-
els . By contrast, set the control RELEASE to
a short time . Thus, the beginning of the
next syllable will not be attenuated .
b . Short attack times will be required for per-
cussion instruments as the highest volume
will appear at the start of a percussion .
c . For bass compression, adjust longer attack
and release times . If these times are too
short, distortions will result .
d . Longer release times will be required for
instruments played in a very dynamic way,
such as electric guitars . A short release
time would smooth out tremolo variations .
To compress the stereo sum of a mixer, also
adjust a longer release time; otherwise,
the level of the signal will be decreased
and immediately increased again in case
of a volume peak . A "pumping effect"
will result .
e . The optimum attack and release times
largely depend on the type of application
and will require both intuition and experi-
ence . Different settings should be tested .
14

6.4 Adjusting the limiter

Independent of the expander and the com-
pressor, the limiter will monitor the output
level and limit the signal to a maximum value
adjusted . Thus, it will be possible, e . g . to pro-
tect audio recordings and power amplifiers
against overload and speakers against dam-
age . Short upper deviations from the level
adjusted will be radically limited; in case of
longer deviations, the level of the entire signal
will be reduced .
Adjust the maximum admissible output
level with the control THRESHOLD (24) . In
case of limiting, the LED LIMITER (9) will light
up . In addition, the reduction of the level will
be shown by the indication GAIN REDUC-
TION (8) .
If the LED LIMITER lights up frequently,
the level should be generally slightly reduced
with the control OUTPUT GAIN (22) or a
higher compression should be adjusted .

6.5 SIDECHAIN FILTER

When the button SC FILTER is pressed, the
control signal for signal processing will pass
a high-pass filter . This will reduce a "pumping
effect" which may occur in bass-accented
music where the bass notes cause a pulsed
compression of the entire signal .

6.6 Sidechain applications

A sidechain is the circuit of the control sig-
nal . Usually the control signal will directly be
derived from the audio signal and will affect
the output level, depending on the values
adjusted for the expander, the compressor
and the limiter .
This control signal may additionally be
processed externally before it monitors the
dynamics of the audio signal, or an external
signal may be used for control . Examples of
application can be found below .

6.6.1 Frequency-dependent dynamics

de-esser, expander/gate

To suppress sibilance with voice record-
ings, insert an equalizer via the jacks
SIDECHAIN SEND (33) and RETURN (34)
( ☞ chapter 5 .3) .
1) Engage the button SC EXT (5) so that
the signal processed externally will take
control .
2) Adjust the equalizer as a band-pass filter
in such a way that only frequencies in the
range 6 – 8 kHz will pass through .
To check the control signal acousti-
cally, press the button SC MONITOR (14)
to switch the signal to the output .
Thus, the compressor will operate as a
"de-esser" to attenuate sibilant sound .
In the same way, the expander/gate
section can be controlled via a band-pass
filter matched to the corresponding instru-
ment, e . g . to improve channel separation
when several microphones are used .

6.6.2 Externally controlled dynamics

ducker, expander/gate

With a ducker, the audio signal will be com-
pressed as a function of an external signal .
For reducing a music signal depending on
a microphone signal, e . g . for a presenta-
tion: Feed the microphone signal to a mixer
and, after preamplification, also to the jack
SIDECHAIN RETURN (34) . Connect the music
signal to the compressor input . Apply the
compressor output to the second input of
the mixer .
Adjustments on the compressor:
1) Engage the button SC EXT (5) so that the
external signal will take control .
2) With the control THRESHOLD (15), ad-
just the microphone volume at which the
music signal is to be attenuated .
3) Adjust the music attenuation with the con-
trol RATIO (17) .
4) Set the button MANUAL /AUTO (19) to
MANUAL (disengage it) and adjust a short
attack time with the control ATTACK (18)
so that the music signal will be attenuated
immediately when you start talking .
5) With the control RELEASE (20), adjust the
time until the music will reach its normal
volume again after a microphone an-
nouncement (soft fade-in) .
6) To check the control signal acoustically,
press the button SC MONITOR (14) to
switch it to the output .
The expander/ gate section can be controlled
via an external signal in the same way . As an
effect to emphasize the rhythm, e . g . a bass
note can be synchronized with the beat of a
bass drum (via the input SIDECHAIN RETURN) .
Notes:
– If the jack SIDECHAIN RETURN (34) is not used,
the internal sidechain signal will always control
the dynamics, regardless of the switch position
SC EXT (5) .
– The inputs SIDECHAIN SEND (33) and the outputs
SIDECHAIN RETURN (34) will not be matched to the
level −10 dBV when the switch +4 dBu / −10 dBV
(30) is pressed .