Introduction – Drawmer MX30 Pro Gated Compressor / Limiter User Manual

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The MX30 is a dual channel gate and compressor-limiter designed to fulfil the needs of
professional studio and live sound applications. It may be used in balanced systems at
+4dBu operating levels, or unbalanced at -10dBu.

In order to maximise flexibility while simplifying set up and operation, several new
design concepts have been incorporated. The compressor section combines aspects
of both the traditional ratio style compressor and the soft-knee approach, making it
equally adept at creative work and unobtrusive level control. The control layout
resembles that of a straight ratio style unit but the transition from unity gain to gain
reduction at the selected ratio is progressive and occurs over a nominal 10dB input level

Traditionally, soft-knee compressors have been preferable for unobtrusive level control
where the original sound is to be changed as little as possible, whereas ratio type
compressors are generally considered more successful in creative applications or where
large amounts of gain reduction are required. By combining these two elements, the
MX30 is capable of outstanding results in a very wide range of studio and live sound

One of the perennial problems in using compression is that maximum system gain
occurs during extremely quiet passages or pauses which results in an increase in
background noise, the degree depending on how much compression is being used. The
accepted way of dealing with this problem is to include in the compressor, a separate
gate section with its own threshold control so that a low level gating action may be
applied to keep pauses clean. However, the problem with simple gates is that, even
when properly set up, they may unwittingly process low level sounds as they have no
means of identifying them from noise. On a vocal track, for example, this can lead to the
starts or endings of words being accidentally removed, especially if the singer has a
wide dynamic range.

The MX30 uses a proprietary Programme Adaptive gate circuit that varies its ratio
depending on the dynamics of the signal being processed. Because the onset of gating
is progressive, those low level signals most at risk will be treated to a lower ratio of
gating (like an expander) while the residual noise during pauses will be subjected to a
higher expansion ratio and will, in consequence, be attenuated more. The outcome is
a gate that requires less stringent setting up and is more tolerant of wanted sounds that
are only slightly above the residual noise floor.

A further feature of the MX30 is a peak limiter that allows the user to set an absolute
output signal level that will not be exceeded. If the peak limiter threshold is exceeded
for more than a few milliseconds, additional gain reduction will be applied to reduce the
overall signal level to within accepted limits without distortion. Once the peak has
passed, the system gain will return to normal over the period of about one second. This
facility is extremely valuable both in live sound applications, for driver protection, and
in digital recording where an absolute maximum recording level exists. Furthermore,
when overdriven, it can be used creatively to produce deliberate level pumping effects.

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