DBX 2231 User Guide

8760 S. Sandy Pkwy.

Sandy, Utah 84070

Phone (801) 568-7660

Fax (801) 568-7662

Int’l Fax (801) 568-7583

customer@dbxpro.com

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 channels 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 monitoring of gain reduction and output levels–the most comprehensive visual feedback available

• Exceptional sound quality

• dbx’s unmatched engineering and construction standards

2231

DUAL CHANNEL 31 BAND EQUALIZER WITH TYPE III™ NOISE REDUCTION

2231

DUAL CHANNEL 31 BAND EQUALIZER WITH TYPE III™ NOISE REDUCTION

2231

DUAL CHANNEL 31 BAND EQUALIZER WITH TYPE III™ NOISE REDUCTION

2231

DUAL 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 channels 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 T ype 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 technology allows you to easily safeguard your gear against hazardous dynamic surges 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 ladders. 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 compromising your sound.

18-1720-C 12/99

III

2231

Equalizer/Limiter

with TYPE

+15

-15

+15

-15

dBu

0OFF

+12

-12

-6

RANGE

PeakPlus

THRESHOLD

CUT

LOW

GAIN

INPUT

BYPASS

III

TYPE

20 25 31.5 40 50 63 80 500400315250 1.6k1.25k1k800 5k4k3.15k2.5k 16k12.5k10k8k6.3k 20k2k630100 125 160 200

13610+18+100-10

+/-6

+/-15

GAIN

REDUCTION (dB)

OUTPUT

LEVEL (dBu)

CLIP

+20+5

+15+10

13610+18+100-10

+/-15

GAIN

REDUCTION (dB)

OUTPUT

LEVEL (dBu)

CLIP

-6

+/-6

+20+5

RANGE

+15+10

dBu

PeakPlus

0OFF

THRESHOLD

CUT

LOW

+12

GAIN

INPUT

-12

BYPASS

III

TYPE

FOR MORE INFORMATION CONTACT:

dbx Professional Products

8760 S. Sandy Pkwy.

Sandy, Utah 84070

Phone (801) 568-7660

Fax (801) 568-7662

Int’l Fax (801) 568-7583

customer@dbxpro.com

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 terminals 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 equalizer 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 24W. 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 Ultra Quiet Equalizer/Limiter.

dbx engineers are constantly working to improve the quality of our products. Specifications are, therefore subject to change without 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: 23W Mains Connection: IEC receptacle

Physical

Dimensions: 5.25" H X 19" W X 7.9" D (13.335cm x 48.3cm x

20.1cm) Weight: 10.6 lbs. (4.8081 kg) Shipping Weight: 11.6 lbs. (5.267 kg)

Note: Specifications subject to change.

586

Dual Vacuum Tube Preamp

TYPE IV™ Conversion System

704

2231

DUAL CHANNEL 31 BAND EQUALIZER / LIMITER WITH TYPE III™ NOISE REDUCTION

13610+18+100-10

GAIN

REDUCTION (dB)

+/-15

+15+10

+/-6

+20+5

0 OFF

dBu

RANGE

LOW

PeakPlus

CUT

GAIN

THRESHOLD

-6

20 25 31.5 40 50 63 80 500400315250 1.6k1.25k1k800 5k4k3.15k2.5k 16k12.5k10k8k6.3k 20k2k630100 125 160 200

13610+18+100-10

GAIN

REDUCTION (dB)

+/-15

+15+10

+/-6

+20+5

0 OFF

dBu

RANGE

LOW

PeakPlus

CUT

GAIN

THRESHOLD

-6

OUTPUT INPUT

INPUTOUTPUT

CAUTION:

TO REDUCE THE RISK OF FIRE REPLACE ONLY WITH SAME TYPE FUSE.

ATTENTION:

UTILISER UN FUSIBLE DE RECHANGE DE MEME TYPE.

PROFESSIONAL PRODUCTS A HARMAN INTERNATIONAL COMPANY MODEL 2231 EQUALIZER/LIMITER WITH TYPE III NOISE REDUCTION

RISK OF ELECTRIC SHOCK

DO NOT OPEN

ATTENTION:

RISQUE DE CHOC ELECTRIQUE - NE PAS OUVRIR

WARNING:

TO REDUCE THE RISK OF FIRE OR ELECTRIC

SHOCK DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE

MANUFACTURED UNDER ONE OR MORE OF THE FOLLOWING U.S. PATENTS: 4,234,804 4,316,107 4,329,598 4,331,931 4,377,792 4,403,199 4,409,500 4,425,551 4,434,380 4,454,433 4,471,324 4,473,793 OTHER PATENTS PENDING

OUTPUT

INPUT

CONNECTOR POLARITY

PHONE:

XLR:

TIP

PIN 1

RING

PIN 2

SLEEVE

OUTPUT INPUT

PIN 3

OUTPUT

INPUT

TYPE

III

LEVEL (dBu)

CLIP

-120+12

BYPASS

LEVEL (dBu)

CLIP

-120+12

BYPASS

POWER

24 WATTS

100V 50/60Hz

120V 60Hz

OUTPUT

INPUT

OUTPUT

INPUT

+15

-15

Equalizer/Limiter

+15

with TYPE

-15

2231

III