E Q / D Y N A M I C S S E C T I O N
page 18
D-12 / July 2006
EQ Section
The EQ section consist of a bank of knobs
and switches that operate the equalizer, a four
band, parametric design with sweepable center
frequency, bandwidth, and boost/cut controls.
Shelving curves may be independently selected
for low and high bands. Separate High Pass,
Notch, and Low Pass filters may also be in-
serted. EQ control is accessible by selecting an
input or master fader SET button. EQ width
follows the width of the selected source (i.e.,
stereo or 5.1). An integral meterbridge LCD
display draws a real-time composite equaliza-
tion curve based on the knob and switch settings.
Dobbying any boost/cut (+/-) knob will toggle
the parameter between flat and the current value.
To access EQ on an individual input chan-
nels, press the appropriate channel’s SET button
and make the desired adjustments in the EQ
Section. To actually place the adjusted EQ in the
signal chain, press the channel’s EQ button in the
IS-D12 panel. The input channel’s EQ button
will light, and its LCD display will show “EQ”.
High-Pass Filter
This is a 24dB/octave variable high-pass fil-
ter with Butterworth characteristics, tunable be-
tween 16.1Hz and 500Hz, and with a separate in/out switch (“HPF”
switch). The relatively high order of filter is necessary to allow definite
and decisive removal of unwanted low-frequency artifacts (air-condi-
tioning rumble, line hum, traffic or footstep impacts) with minimal
effect on the required program. The display indicates the filter’s
frequency, and the filter may be clicked in and out by way of the IN
switch.
Notch Filter
This 1/10th octave, variable center frequency notch filter is tunable
between 16.1Hz and 20.2KHz. This filter is used to remove specific
audio frequencies, such as 60Hz or 120Hz for an AC power line hum or
buzz, or perhaps a horizontal scanning interference from a monitor. The
display indicates the filter’s center frequency, and the filter may be
clicked in and out by way of the IN switch.
Note: Butterworth Filters
typically yield excellent
flatness, no ripple in the
pass band, and a rounded
amplitude response near
the cutoff frequency.
