dbx 2231 Installation and operation manual

8760 S. Sandy Pkwy.
Sandy, Utah 84070
Phone [phone]
Fax [phone]
Int’l Fax [phone]
[email protected]
http://www.dbxpro.com
A Harman International Company
• dbx’s revolutionary Type III™
Noise Reduction system, which
increases S/N ratio by up to
20dB
• PeakPlus™ limiting technology
with threshold range from 0dBu
to +24dBu (off)
• Two 31-band, 1/3-octave chan-
nels with switchable boost/cut
ranges of +6 or +15 dB
• +12 dB input gain range
• XLR, Barrier strip, and 1/4"
inputs
• 4-segment LED ladders for mon-
itoring of gain reduction and
output levels–the most compre-
hensive visual feedback available
• Exceptional sound quality
• dbx’s unmatched engineering and
construction standards
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
0OFF
+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
0OFF
+20+5
+15+10 +/-6
+/-15
CLIP
13610+18+100-10
0
-15
+15
0
-15
+15
0
-6
+6
0
-6
+6
2231DUAL CHANNEL 31 BAND
EQUALIZER WITH
TYPE III™ NOISE REDUCTION
2231DUAL CHANNEL 31 BAND
EQUALIZER WITH
TYPE III™ NOISE REDUCTION
2231DUAL CHANNEL 31 BAND
EQUALIZER WITH
TYPE III™ NOISE REDUCTION
2231DUAL CHANNEL 31 BAND
EQUALIZER WITH
TYPE III™ NOISE REDUCTION
®
With a prestigious heritage extending back to our heralded 30 Series equalizers, the dbx
2231 easily lives up to the reverred dbx reputation. Besides including two 31-band chan-
nels of 1/3-octave equalization, the 2231 empowers you with flexible features like our
PeakPlus™ limiter circuit, and our amazing Type III™ Noise Reduction system. It also
includes +12 dB input gain range; switchable + 6 or + 15 dB boost/cut range; XLR,
Barrier strip, and 1/4'' inputs; nonconductive nylon sliders; and an intuitive user interface
with comprehensive output and gain reduction metering. As always, the inevitable result
of our meticulous attention to detail and top-quality componentry is exceptional sound,
performance, and reliability.
The most revolutionary feature of the 2231 is our proprietary Type III™ Noise Reduction
system, which enables you to boost signal-to-noise ratios by up to an incredible 20dB.
The result of this instant encode/decode process is that you’re no longer forced to employ
drastic EQ settings in effort to reduce system noise. Instead, you’re freed to dedicate all
EQ bands to the most important thing, the music. Further , our PeakPlus™ limiter tech-
nology allows you to easily safeguard your gear against hazardous dynamic sur ges in
program material. In addition to these formidable tools, the 2231’ s front panel provides
at-a-glance insight as to gain reduction and output level status via its four-stage LED lad-
ders. With such power and finesse built into such a reasonably priced package, it’ s easy
to see why dbx 20 Series equalizers are relied upon by studio and touring professionals
the world over. With such affordable quality, there’s no longer any excuse for compro-
mising your sound.
18-1720-C 12/99

FOR MORE INFORMATION CONTACT:
dbx Professional Products
8760 S. Sandy Pkwy.
Sandy, Utah 84070
Phone [phone]
Fax [phone]
Int’l Fax [phone]
[email protected]
http://www.dbxpro.com
A Harman International Company
The graphic equalizer shall be a dual 31-band type with frequency centers on standard ISO
one-third octave frequencies ranging from 20Hz to 20kHz. The boost/cut ranges shall be
switchable via recessed front panel switches to either +/-6dB or +/-15dB and the selected
range shall be indicated on the front panel by either of two LEDs per channel. Low-noise
equalization sliders having a 45mm travel shall be utilized having center detents at 0 dB. The
equalizer shall have front panel 41-detent rotary input gain controls having a +/-12dB range.
Bypassing the equalizer sections of the signal path shall be accomplished via front-panel
switches having corresponding LEDs to indicate when each channel is bypassed. A 40Hz
low-cut Bessel filter per channel with 18dB/octave slope shall be insertable in the signal path
via front panel recessed switches with LEDs to indicate when the filters are active.
The graphic equalizer shall incorporate dbx Type III™ Noise Reduction providing up to 20dB
of broadband noise reduction, having front panel switches to enable the noise reduction and
LEDs to indicate when it is active. The equalizer shall also be equipped with dbx PeakPlus™
limiters having front panel 41-detent rotary limiter threshold controls varying from 0 to
+24dBu (off) and four-LED gain reduction bar graphs calibrated to read 0, 3, 6, and 10dB.
Output levels shall be monitored on four-LED peak-reading bar graphs calibrated to read -10,
0, +10, and +18dBu.
Electronically balanced/unbalanced inputs shall include 1/4" TRS, female XLR, and screw
terminal barrier strip, while servo-balanced/unbalanced outputs shall include 1/4" TRS, male
XLR, and screw terminal barrier strip shared with the input. A circuit/chassis ground lift
jumper per channel shall be strapped across circuit ground and chassis ground screw termi-
nals and shall be removable by the user . Inputs shall be electronically balanced/unbalanced
and RF filtered having a nominal input impedance not less than 40kS balanced and 20kS
unbalanced, and shall accept maximum signal levels of not less than +21dBu. Outputs shall
be servo-balanced/unbalanced and RF filtered having a nominal output impedance of not
more than 200S balanced and 100S unbalanced, and shall be capable of driving not less than
+21dBu into 2kS or greater and not less than +20dBm (into 600S) continuously .
Frequency response shall be better than 10Hz to 50kHz, +0.5/-3dB. Signal-to-noise ratio shall be greater than 90dB, referenced to +4dBu, in either boost/cut range
with noise reduction disabled and shall be greater than 102dB with noise reduction enabled. THD+Noise shall be less than 0.04% with a 1kHz signal at +4dBu,
while interchannel crosstalk shall be lower than -80dB from 20Hz to 20kHz.
The internal power supply shall be constructed using a thermally-fused transformer mounted in a low hum orientation and shall be magnetically isolated from equal-
izer circuitry by means of a mu-metal shield. The power cord shall be detachable from an international standard IEC 320 power inlet receptacle. Unit shall be
constructed to meet or exceed all applicable international safety and regulatory agencies. Domestic unit shall be powered from 100VAC 50/60Hz, 120VAC 60Hz,
while international unit shall be powered from 230VAC 50/60Hz. Unit shall consume no more than 28W. Housing shall be of all steel/aluminum construction and
shall be rack-mountable in an IEC standard 19" rack and shall occupy a 3U (5.25") rack space. The unit shall be a dbx 2231 Ult ra Quiet Equalizer/Limiter.
dbx engineers are constantly working to improve the quality of our products. Specifications are, therefore subject to change wi thout notice.
Inputs
Connectors: 1/4” TRS, female XLR (pin 2 hot), and barrier ter-
minal strip
Type: Electronically balanced/unbalanced, RF filtered
Impedance: Balanced 40kS, unbalanced 20kS
Max Input Level: >+21dBu balanced or unbalanced
CMRR: >40dB, typically >55dB at 1kHz
Outputs
Connectors: 1/4” TRS, male XLR (pin 2 hot), and barrier termi-
nal strip
Type: Impedance-balanced/unbalanced, RF filtered
Impedance: Balanced 200S, unbalanced 100S
Max Output Level: >+21dBu balanced/unbalanced into 2kS or
greater
>+20dBm balanced/unbalanced (into 600Ω)
System Performance
Bandwidth: 20Hz to 20kHz, +/-0.5dB
Frequency Response: <10Hz to >50kHz, +0.5/-3dB
Noise Reduction In (+/-6 and +/-12dB range):
Signal-to-Noise: >102dB, unweighted, ref: +4dBu, 22kHz measure-
ment bandwidth
Dynamic Range: >120dB, unweighted
Noise Reduction Out: (+/-6dB range):
Signal-to-Noise: >94dB, unweighted, ref: +4dBu, 22kHz measur-
ment bandwidth
Dynamic Range: >112dB, unweighted
Noise Reduction Out: (+/-12dB range):
Signal-to-Noise: >90dB, unweighted, ref: +4dBu, 22kHz measure-
ment bandwidth
Dynamic Range: >108dB, unweighted
THD+Noise: <0.04%, 0.02% typical at +4dBu, 1kHz
Interchannel Crosstalk: <-80dB, 20Hz to 20kHz (2215/2231)
Noise Reduction: Up to 20dB of dynamic broadband noise reduction
Function Switches
Type III NR: Activates dbx Type III‘ Noise Reduction
EQ Bypass: Bypasses the graphic equalizer section in the sig-
nal path
Low Cut (recessed): Activates the 40Hz 18dB/octave Bessel high-pass
filter
Range (recessed): Selects either +/- 6dB or +/- 15dB slider boost/cut
range
Indicators
Output Level Meter: 4-LED bar graph (Green, Green, Yellow, Red) at -
10, 0, +10, and +18dBu
Gain Reduction Meter: 4-LED bar graph (all Red) at 0, 3, 6, and 10dB
Type III NR Active: Yellow LED
EQ Bypass: Red LED
Clip: Red LED
Low Cut Active: Red LED
+/-6dB range: Red LED
+/-12dB range: Red LED
Power Supply
Operating Voltage: 100VAC 50/60Hz, 120VAC 60Hz
230VAC 50/60Hz
Power Consumption: 28W
Mains Connection: IEC receptacle
Physical
Dimensions: 3.5" H X 19" W X 7.9" D (8.9cm x 48.3cm x
20.1cm)
Weight: x.x lbs. (x.x kg)
Shipping Weight: x.x lbs. (x.x kg)
Note: Specifications subject to change.
586 Dual Vacuum Tube Preamp
TYPE IV™ Conversion System
704
DUAL CHANNEL 31 BAND EQUALIZER / LIMITER WITH TYPE III™ NOISE REDUCTION
2231
2231DUAL CHANNEL 31 BAND
EQUALIZER WITH
TYPE III™ NOISE REDUCTION
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
0
-6
+6
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
-6
+6
0
-15
+15
0
-15
+15
2231
Equalizer/Limiter
with TYPE III NR
OUTPUT
- +
INPUT
- +
OUTPUT INPUT
PHONE:
TIP
RING
SLEEVE
XLR:
PIN 1
PIN 2
PIN 3
CONNECTOR POLARITY
INPUTOUTPUT
OUTPUT
- +
INPUT
- +
OUTPUT INPUT
INPUTOUTPUT
100V 50/60Hz
120V 60Hz
PROFESSIONAL PRODUCTS
A HARMAN INTERNATIONAL
COMPANY
MODEL 2231
EQUALIZER/LIMITER WITH
TYPE III NOISE REDUCTION
WARNING: TOREDUCETHERISKOFFIREORELECTRIC
SHOCKDONOTEXPOSETHISEQUIPMENTTORAINORMOISTURE
RISKOFELECTRICSHOCK
DONOTOPEN
ATTENTION: RISQUEDECHOCELECTRIQUE-NEPASOUVRIR
CAUTION: TOREDUCE
THERISKOFFIREREPLACE
ONLYWITH SAME TYPE FUSE.
ATTENTION: UTILISER
UNFUSIBLEDERECHANGEDE
MEMETYPE.
POWER
MANUFACTURED UNDER ONE OR MORE OF THE FOLLOWING
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