User guide

2
OPERATION MANUAL
introduCtion
Congratulations on your purchase of a dbx graphic equalizer. All dbx graphic equalizers are high performance multi-
functional units designed to deliver all the flexibility and power that professional users demand. We recommend that
you take a moment to read through this operation manual. It provides information that will assist you from system set-
up to EQ applications. The 20 Series Equalizers include the following features:
 •RevolutionarydbxTYPEIII™NoiseReductioncapableofrestoringupto20dBS/Nratio
 •Proprietarypatent-pendingPeakPlus™Limiterforsystemprotection
 •Switchablerangebetween±6dBand±15dB
 •Balancedinputsandoutputs
 •XLR,BarrierStrip,and1/4”TRSconnectors
 •-12dB/+12dBinputgainrange
 •18dB/octave40HzBesselLow-Cutfilter
 •Chassis/signalgroundliftcapability
 •Internalpowersupplytransformer
 •Power-offhard-wirerelaybypasswith2-secondpower-updelay
inspeCtion
Verify that the equalizer’s package contains the following:
 •Equalizerunitmatchingserialnumbermarkedonpackage
 •ACpowercord
 •OperationManual
 •RegistrationCard
 •Fourrackmountscrewsandwashers
If any of these items are missing please contact dbx customer service at the number provided on the back cover of this
manual.
operating Controls
Front Panels
2031-singlechannel31bandgraphicequalizer
2231-dualchannel31bandgraphicequalizer
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
20 25 31.5 40 50 63 80 500400315250 1.6k1.25k1k800 5k4k3.15k2.5k 16k12.5k10k8k6.3k 20k2k630100 125 160 200
0
-15
+15
3610+18+100-10
2031
Equalizer/Limiter
with TYPE
III NR
85-2564-A0 2031 FRONT ART 12-16-96
2231
Equalizer/Limiter
with TYPE III NR
20 25 31.5 40 50 63 80 500400315250 1.6k1.25k1k800 5k4k3.15k2.5k 16k12.5k10k8k6.3k 20k2k630100 125 160 200
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
13610+18+100-10
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
13610+18+100-10
0
-15
+15
0
-15
+15
0
-6
+6
0
-6
+6
85-2568-A0 2231 FRONT ART 12-16-96