Table of Contents
Advertisement
274
Chapter 16: Application Notes
Knee
The soft knee curves behave in a traditional way to blend the compression ratio around
the threshold setting (as described above), but more importantly they also have a
significant effect on the attack envelope shapes. The soft knee typically slows down
attack speed on signals in the knee area, which is desirable for natural sounding
compression because it compliments the reduced ratio effect of the soft knee. This
produces very gentle compression in the knee region.
The KNEE switch has three settings: hard (4dB); medium (12dB): and soft (40dB). In
hard setting the compressor still retains some soft knee characteristics. This is because
the implementation of an extremely hard knee produces undesirable sounding
distortion on low frequency programme material.
More
As a default (and even though they are different) all the compressor signatures have
been designed to sound as pure and natural as possible. To achieve this, many of the
undesirable artefacts that are commonplace amongst analogue compressors have been
eliminated; most notably the negative effects of soft knee and/or high signal amplitude.
Both of these can artificially speed up release times in a way that is difficult to correct
by envelope adjustment because it only occurs on specific parts of the programme.
This can normally be heard as pumping or distortion, depending on the setting of the
envelope controls.
There are circumstances when this correction process is not desirable and the MORE
switch can be used as an override to get greater character from the compressor
signatures. This tends to accentuate the differences between them and emphasises
transients as well as increasing pumping and distortion. This can notably change the
sound of the programme as well as providing dynamic control.
Corrective mode (exponential peak - fast)
This is a peak sensing compressor (like many older designs) with exponential attack
and release. It produces aggressive compression that gives good fast control and/or
limiting of dynamic material. It can be used to add colour to low frequency signals
(especially if used in conjunction with MORE) making it ideal for controlling extremely
dynamic instruments like the bass guitar. The compressor tends to sound best with
fast attack time settings that capture transients and with release adjusted to taste to
either emphasise or minimise distortion and pumping effects.
Adaptive mode (exponential RMS - accurate)
This is a root-mean-square (RMS) sensing compressor with exponential attack and
release. The RMS averaging process interacts with the attack and release to produce a
very adaptive envelope character. This allows faster attacks on large (over-threshold)
signal changes and produces slower attacks on small signal changes, regardless of
attack time setting. The attack control is still active, allowing some user intervention
although the adaptive nature makes envelope control setting fairly non-critical. The
compressor is therefore very fast and simple to set up on most programme material. It
is also sonically accurate and works well for both compression and limiting of vocals and
many other sources. The most natural sounding compression is normally achieved with
soft knee settings.
XL8 Control Centre
Operator Manual
Advertisement
Table of Contents
