The Compressor Section - Behringer Composer PRO-XL MDX2600 User Manual

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MULTICOM PRO-XL MDX4600/PRO-XL MDX2600/AUTOCOM PRO-XL MDX1600 User Manual
Application hints
The purpose of using an expander is usually to expand the usable dynamics
towards the lower end, i.e. to improve the separation between low-level signals
and the unavoidable noise floor by reducing the noise level.
Start setting up the expander by turning the TRIGGER control from position
OFF clockwise until the LEDs show the onset of the gain reduction. Preferrably,
you should use some music material containing pauses and soft passages, so as
to hear whether the beginnings or endings of words are cut off by the expander
or are suppressed too much. If necessary, experiment with the release time or
reduce the threshold a little bit.
Gates work basically in the same way, the major difference being the fact that
they reduce gain to a much greater extent. Once the level drops below threshold,
the signal is muted completely.
The classic application of a gate is the separation of signals delivered by multiple
microphones in a multitrack recording. Especially when drums are recorded,
a gate is almost indispensable to avoid crosstalk, e.g. of the cymbals into the floor
tom microphones.
However, you should always try to use the microphones and their directivity in
the first place to achieve some degree of channel separation and hence a better
and more natural result. Subsequently, a gate helps you optimize your set-up.
The program-dependent IRC allows you to set both gate and expander easily and
conveniently. Nevertheless, you should experiment with different release times
and trigger settings to get a perfect result!

2.2 The compressor section

(11) (12) (14) (20) (19)
(6) (22) (10) (18) (21)
MDX4600
(7) (9) (11) (14) (17) (20) (19)
(6) (8) (12) (10) (13) (15) (16) (22) (21) (18)
MDX4600
(7) (9) (11) (14) (19)
(6) (10) (8) (12) (13) (15) (16) (18) (25) (21)
MDX1600
Fig. 2.3: Compressor section control elements
(20)
(6) Use the THRESHOLD control to adjust the compressor threshold from
-40 to +20 dB.
(7) These three LEDs (AUTOCOM PRO-XL and COMPOSER PRO-XL only) indicate
whether the input signal is above or below the adjusted compressor
threshold. The yellow LED in the middle refers to the IKA "soft knee" range
(if IKA is on).
(8) Activating the SC EXT switch interrupts the link between the signal
input and the compressor control section. At the same time, an external
control signal can be fed in via the rear panel SC RETURN jack, taking over
control of the input signal dynamics reduction. You can, for example,
intensify the control function in a specific frequency range by inserting an
equalizer via the SC SEND AND SC RETURN jacks. Detailed information on
this special application can be found in chapter 3 "Examples of Sidechain
Applications". This function, too, is only available on the AUTOCOM PRO-XL
and COMPOSER PRO-XL.
(9) The SC MON switch links the sidechain input signal to the audio output,
thereby muting the audio input signal. For example, this allows you to
pre-monitor the sidechain signal in combination with an equalizer or other
device inserted into the sidechain channel. The SC MONITOR function makes
it easier to for example adapt the equalizer filters to the control signal.
◊
With the SC MONITOR switch activated, only the side-chain signal will
be present at the output, which is shown by the flashing LED switch!
(10) The RATIO control determines the ratio of input vs. output level with
regard to all signals exceeding threshold by more than 10 dB. Although the
compression starts earlier, the IKA characteristic ensures the smooth,
inaudible onset of the gain reduction, which is why the ratio value will be
reached only with 10 dB or more above threshold. It can be set continuously
from 1:1 (no compression) to oo :1 (limiter).
(11) The 12-digit GAIN REDUCTION display (MDX4600: 8-digit) informs you
about the current gain reduction applied (1 to 30 dB).
(12) The LO CONTOUR switch activates a high-pass filter in the side-chain
path and thus avoids the "pumping" effect caused by high-energy bass
frequencies and their influence on the compression process.
(13) Use the ATTACK control to determine when the compression sets in once the
signal has exceeded threshold (MDX1600 and MDX2600 only). The setting
range is from 0.3 to 300 ms.
(14) Press the INTERACTIVE KNEE switch to change from "hard knee" to
IKA characteristic: Input signals exceeding threshold by up to 10 dB will
be processed with a "soft knee" characteristic. Above 10 dB the control
characteristic changes from "soft knee" to a more conventional "hard knee"
compression. The IKA characteristic allows for a subtle and musical
compression of the program material, and should be used whenever
inaudible compression is desired.
(15) The AUTO function, which is activated with the AUTO switch, disables the
ATTACK and RELEASE controls and derives these time values automatically
from the program material. It thus allows for a heavy and, at the same
time, musical compression of signals with varying levels or of complex
program material.
(16) The RELEASE control (MDX1600 and MDX2600 only) sets the time when the
original 1:1 gain is reached, after the signal has dropped below threshold
again. The setting range is from 0.05 to 5 s.
(17) Use the TUBE switch (MDX2600 only) to enhance the output signal
with the warm and transparent tonal character typically produced by
electronic tubes.