Using The De-Esser - Orban 424A Operating Manual

Because
peak output
levels
are held relatively constant, you can
readily
hear the
effect
of
adjusting
any
control
upon
the
relative loudness
achieved by the
processing. Fast attack and release
times and
high
ratios result
in
maximum
loudness
(i.e.,
low peak-to-average
ratios),
but introduce the greatest
risk of audible
side-effects.
In
the
424A,
special circuitry
minimizes
these effects
when compared
to conventional limiters
and compressors.
If
the
VCA LEVEL
meter
reads
in
the red, there
is
danger
of clipping
the
compressor/limiter's
voltage-controlled amplifier
(VCA), and
the
OUTPUT
TRIM
control should be turned
down.
If
the
VCA
LEVEL
meter
reads substantially
below
OdB (which may
occur
if
low compression
ratios
are being used with small amounts
of
gain reduction), you
may
turn the
OUTPUT
TRIM
control up
if
you wish
to
improve
the signal-to-noise ratio achievable
from
the
424A
itself.
(Usually, noise
from
the
program
material
will
dominate
noise
generated within the
424A, and
this
exercise
may
be academic.)
The
OUTPUT
TRIM
control
can
also
be turned up
if
you wish
to
purposely
clip
the
VCA
to control
low-energy overshoots by
clipping instead of by gain reduction.
This permits the use
of
slower attack times, and
may
result
in
a
more
natural
sound.
If
you want the
gain
to
recover
to
maximum
during
pauses, turn
the
GATE
THRESH
control
fully
counterclockwise (OFF).
If
you wish the
VCA
to settle to
a
certain
user-specified gain during pauses, adjust the
GATE THRESH
control to
determine
the
level at
which
this
gating occurs,
and
adjust
the IDLE
GAIN
control
to the gain desired.
(Compression
is
most unobtrusive
if
this control
is
adjusted to
correspond
to
the
average
gain reduction being used.)
Using The De-Esser
The
de-esser
is
functionally located after the compressor/limiter,
and
is
essentially
independent
of
it.
The compressor/
limiter
is
ordinarily
used
to control input levels
to
the de-esser, assuring a
constant amount
of de-essing. This
is
because
the de-
esser attempts
to
reduce
all
si
bi
lance
("ess"
sounds) to a
level
fixed by the de-esser
THRESHOLD
control, instead of to a
level
which
is
some
fraction
of
the
average
input
level (as
the
Orban
dedicated de-essers
do).
The
de-esser
in
the
424A
therefore
does not track
its
input level,
which must
be reasonably constant to
assure
consistent
balance between
sibilance and other
(voiced)
vocal sounds.
To
use the de-esser, switch the
DE-ESSER OPerate/DEFEAT
switch
to
OP.
After
you have
adjusted the controls
in
the compressor/limiter section for the desired
effect, adjust the de-esser
THRESHOLD
control
until
sibilance levels
sound natural
and properly balanced.
The NORMal
light will
flash
whenever
de-essing
is
occurring.
If
the
HEAVY
light
flashes,
it
almost
certainly indicates that you have advanced
the de-esser
THRESHOLD
control too far clockwise,
and
that
excessive de-esser gain reduction
is
occurring.
The
de-esser
works by momentarily
decreasing
the gain
of
the entire
program.
Recovery
is
so
quick that vocal sounds surrounding the
sibilance
are
essentially
unaffected.
The
de-esser
is
not a variable lowpass
filter,
and
does not serve as a conventional
high frequency
limiter. Nevertheless,
it
has
been found
that
it
produces effects
similar
to
a high frequency limiter on
some program
material,
and can therefore
sometimes
be used
to control
high frequency
overload on
selected
program
material.
It
may
be
particularly useful
in
de-essing vocals
which have already been
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