Orban 424A Operating Manual page 15

Part
C:
Operating
Instructions
FRONT PANEL
While the
following control descriptions
might
seem
unnecessarily
complex
on
first
DESCRIPTION
reading,
they have been
crafted to
answer any
reasonable question either the
AND
FUNCTION
beginner
or
the experienced
user
might
ask.
The
effects
of,
and interactions
between, the controls have been designed
to
promote
ease
of use, facilitafing
good
results
with
minimum
effort.
Some
of
these interactions
and
effects are
subtle,
and
are
much more
easily
appreciated by
actual
practice than by reading.
Refer
to
the
Front-Panel Photograph
at
the beginning of
this
Manual.
The
GAIN REDUCTION
meter
is
electronically conditioned to
show
the true
peak
gain reduction of fhe compressor/limiter
section,
in
dB.
It
does not
indicate
the
amount
of
de-essing gain
reduction,
which
is
indicated by
illumination of the
NORMal
and
HEAVY
de-essing indicators.
If
the
meter
enters the red part
of
the
scale,
it
indicates that
no further
gain reduction
is
available
in
the compressor/limiter section,
and
that audible
"gulping"
or
other
peculiarities
caused
by the control
loop's
saturating
are
imminent.
The
INPUT
ATTENuator
adjusts the drive
level
to the compressor/limiter,
thus
determining
the
amount
of
gain reduction.
(NOTE:
There
Is
no user-
adjustable
THRESHOLD
control.
However,
adjusting either the
ATTACK
TIME
or
RATIO
controls also adjusts
the threshold
to
keep the peak output
level
approximately constant.)
The COMPression
RATIO
control adjusts the compression
ratio
(i.e.,
the
dB
change
in
input
level
divided
by the
resultant
dB change
in
output
level).
The
calibrations are only valid at the threshold
of
gain reduction.
As more
gain
reduction
is
used, the
compression
ratio increases, yielding a
"soft
knee" curve
when
the
COMPression
RATIO
control
is
adjusted
for
lower
ratios.
Fig.
C-l:
OUTPUT
LEVEL AS A FUNCTION OF INPUT LEVEL
FOR
VARIOUS
SETTINGS
OF THE RATIO
CONTROL
The
ATTACK
I
IME
control scales the program-controlled attack
characteristic
faster
or slower, and simultaneously
adjusts
the compression
threshold. (The
attack time
is
not constant.)