XTA DC1048 - Manual (Page 47)

Operator’s Manual DC1048 Integrated Audio Management Page 47
For an analogue dynamics processor,
the situation is much better.
Controlling the gain electronically, and
not relying on a human sidechain
feedback mechanism, it can react
much more quickly.
The red waveform represents the
input to the dynamics module, with
the dotted line showing the threshold
for gain control to occur. There are
several peaks towards the start of this
signal that are above the threshold,
and so the dynamics processing
should react to these as appropriate.
(In this case reduce the gain).
The blue waveform shows the output of the dynamics module. The circled peak
demonstrates that the processor has missed the first peak above the threshold
(as it is very fast and short), but has ‘caught up’ shortly afterwards, keeping all
other peaks under control. As it is unable to predict what is coming, this will
always be a failing with analogue dynamics processing.
The “D-Max” clip limiter predelays the sidechain signal, resulting in a “zero
overshoot” limiter, which is able to catch all peaks and provide a reliable absolute
maximum setting for the output of any channel.
The predelayed sidechain is shown
in green, with the main signal in
red. As the main signal arrives
slightly after the sidechain, the
output from the unit does not suffer
from the overshoot problem.
Remember that this delay is only in
the order of tens of uS,and is a
predelay – the sidechain is moved
back in time in relation to the main
signal. Inserting a delay into the
main signal path of an analogue
dynamics processor will achieve
similar results, but with the penalty
of delaying the main signal by the
amount of look ahead delay
introduced.
The “D-Max” limiter has only two
parameters to adjust - the release time (either Fast, Medium, or Slow) and the
threshold. Note that the threshold is set to be a minimum of 2dB above the
threshold of the program limiter – setting the threshold to 10dB Above, means
that no more than 10dB of overshoot above the threshold of the program limiter
will ever be allowed. The release time may also be set to follow the High Pass
filter of the output by selecting the “Auto” option on the limiters screen in
ICORE.