OPERATION MANUAL
3
20 SERIES GRAPHIC EQUALIZERS
2215 - dual channel 15 band graphic equalizer
Input Gain Control:
This control sets the signal level to the equalizer. It is capable of -12dB to +12dB of gain. Its
effect is apparent by viewing the OUTPUT LEVEL BAR GRAPH.
EQ Bypass:
This switch removes the graphic equalizer section from the signal path. (See Block diagram on Page
32.) The BYPASS switch does not, however, affect the INPUT GAIN, or LOW CUT filters.
EQ Bypass LED:
This red LED lights when the EQ is in bypass mode. Note that bypass mode only effects the
graphic equalizer section of the 20 Series EQs. The
INPUT GAIN
and and
LOW CUT
controls remain unaffected
when the EQ is bypassed.
Boost/Cut Range Selection Switch and LEDs:
This switch selects which of the two boost/cut ranges the equalizer
will use, either ±6dB or ±15dB. The red LED lights when the ±15dB range is selected, and the yellow LED lights
when the ±6dB range is selected. Note that the BOOST/CUT switch is slightly recessed. This is to prevent acciden
-
tal activation of the switch, possibly causing damage to other sound system components.
Output Level Bar Graph:
These four LEDs indicate output level of the equalizer. The red LED is 3dB below clip
-
ping and is marked as +18dBu. It monitors the level at the output of the equalizer after all other processing, includ
-
ing the limiter.
Clip LED:
This LED lights whenever any internal signal level reaches 3dB below clipping which may occur when
any of the following happen: 1) the input signal is “hotter” than +22dBu, 2) excessive gain is applied by the input
gain control, or 3) excessive boost is applied using the frequency sliders.
Gain Reduction Meter:
These four LEDs indicate the amount of gain reduction being induced by the setting of the
PeakPlus™ LIMITER THRESHOLD
control as the signal level from the graphic EQ section exceeds this limiter
threshold setting.
PeakPlus™ Limiter Threshold Control:
This control engages the PeakPlus™ limiter. It sets the threshold level at
which
∞
:1 gain reduction will begin to occur. Its design is borrowed from the patent-pending PeakStopPlus™
Limiter found on the popular dbx 1066 and 1046 compressor/limiters. It is capable of a range of 0dBu through
“OFF” (+24dBu). When the threshold control is set to “OFF”, the limiter is effectively disabled, and no gain reduc
-
tion will occur.
dbx Type III™ Noise Reduction Switch:
The switch engages the dbx Type III™ Noise Reduction circuit within
the EQ.
dbx Type III™ Noise Reduction LED:
The yellow LED lights when the dbx Type III™ Noise Reduction circuit is
activated via the
NOISE REDUCTION
Switch.
Frequency Band Slider Controls:
Each one of these slider potentiometers will boost or cut at its noted frequency
by ±6dB or ±15dB, depending upon the position of the BOOST/CUT RANGE switch. When all the sliders are in
the center detented position the output of the equalizer is flat. The frequency band centers of the 2031 and the 2231
are marked at 1/3rd of an octave intervals on ISO standard spacings, while the frequency band centers of the 2215
are marked at 2/3rds of an octave intervals on ISO standard spacings.
Low Cut Enable Switch:
The LOW-CUT switch inserts or removes the 18dB/octave 40Hz Bessel low-cut filter
from the signal path. When the LOW-CUT switch is pushed in, the LOW-CUT filter is IN the audio path.
RANGE
GAIN
REDUCTION (dB)
OUTPUT
LEVEL (dBu)
LOW
CUT
EQ
BYPASS
TYPE
III
NR
INPUT
GAIN
dB
-12
0
+12
PeakPlus
THRESHOLD
dBu
0
OFF
+20
+5
+15
+10
+/-6
+/-15
CLIP
1
0
-6
+6
25
40
63
100
160
250
400
16k
10k
6.3k
4k
630
1k
1.6k 2.5k
3
6
10
+18
+10
0
-10
2215
Equalizer/Limiter
with TYPE
III
NR
85-XXXX-A0 2215 FRONT ART 12-16-96
0
-15
+15
RANGE
GAIN
REDUCTION (dB)
OUTPUT
LEVEL (dBu)
LOW
CUT
EQ
BYPASS
TYPE
III
NR
INPUT
GAIN
dB
-12
0
+12
PeakPlus
THRESHOLD
dBu
0
OFF
+20
+5
+15
+10
+/-6
+/-15
CLIP
1
0
-6
+6
25
40
63
100
160
250
400
16k
10k
6.3k
4k
630
1k
1.6k 2.5k
3
6
10
+18
+10
0
-10
0
-15
+15