Drawmer DSL424 TwoPlusTwo Dynamics - Manual (Page 9)

9 DRAWMER DSL424 O
PERATOR’S M ANUA L
Taking the example of the electric guitar, this produces
little below 100Hz or above 3kHz so setting one channel
of the DSL424 to Key Listen mode will enable you to use
the filters to exclude much of the amplifier hum at the low
end and hiss at the top end while having little effect on the
sound of the guitar. Surprisingly, the same is true of the
acoustic guitar; (even a bright-sounding steel-strung
model), and the filters can be used to reduce the effect of
string squeak or the player's breathing.
Other applications of the filter section include shaping DI'd
electric guitar sounds to remove unpleasant overtones and
to simultaneously clean and warm up digital synthesizer
sounds. While we should always endeavour to get the
highest quality of programme material at source, every
engineer is occasionally confronted with inferior material
from sources beyond his control. Conventional equalisers
seldom have a sharp enough response to duplicate the
function of the Key filters which invariably results in the
wanted material being filtered as well as the unwanted
noise. Once a signal has been filtered in this way, it may
also be processed by the second channel of the DSL424
to apply conventional gating.
The unit should be connected in-line with the signal to be
processed via suitable insert points. For mono use, each
channel may be considered as being completely
independent and set up accordingly. For use with stereo
signals such as complete mixes or submixes, the
channels should be switched to Stereo Link mode and all
setting up done using the compressor 1 (left compressor)
channel controls.
Setting up is simplified by the auto attack and release
system which continually optimises the attack and release
times to suit the dynamics of the material being processed.
The ratio setting depends on how firmly the signal dynamics
need controlling; as a rule, higher ratios provide a higher
degree of control but also tend to be more audibly apparent
in operation when high levels of gain reduction are
required. In general, a higher compression ratio may be
used when in Soft Knee mode without compromising the
subjective sound quality.
Having selected Hard or Soft Knee and set a suitable Ratio,
setting up is simply a matter of adjusting the Threshold
control until the desired amount of gain reduction occurs.
This is judged partly by ear and partly by observing the
gain reduction meter. Normally a maximum gain reduction
of between 8dB and 12dB will be adequate. If more gain
reduction appears necessary, it is worth considering
applying a conservative degree of compression during
recording and then further compression while mixing.
Compressing during a mix does increase the subjective
level of tape and other background noises during pauses
and quiet passages as maximum gain is applied when
the signal level is minimum. For this reason, it is unwise
to use more compression than is strictly necessary.
However, using the DSL424 the signal can be patched
through the gate, either before or after the compressor, to
remove any unrequired sounds.
Finally, the Gain control may be set to provide the required
output level using the level meter as a guide. Avoid running
at very high output levels as this reduces the available
amount of signal headroom and could lead to distortion in
extreme cases. Once the gain is correct, the Peak limiter
Level control should be adjusted so that the limiter LED
only lights briefly on extreme signal peaks. Alternatively,
the Peak limiter Level may first be set to the desired value
and then the compressor Gain control adjusted to ensure
minimum limiter activity.
The Peak limiter has no bypass control, but turning the
Level control fully clockwise will effectively prevent the
limiter from operating.
Compressors are often accused of dulling the sound being
processed, but the auto circuitry in the DSL424 has been
designed to allow transient sounds to pass through
cleanly, thus maintaining the clarity and transparency of
the original source. Soft Knee operation is usually
preferable when unobtrusive gain control is required.
The Compressor / Limiter Channels