DBX 1231 User Manual

8760 S. Sandy Pkwy.

Sandy, Utah 84070

Phone (801) 568-7660

Fax (801) 568-7662

IntÕl Fax (801) 568-7583

customer@dbxpro.com

http://www.dbxpro.com

A Harman International Company

The dbx 12 Series were designed to meet the needs of the most demanding sound reinforcement environments, while offering the simplicity of straightforward controls. The 1231 provides standard features like dual-channels, 31 1/3 octave bands, ISO frequency centers, +/- 12 dB input gain range, and switchable 40Hz/18 dB per octave lowcut filters, but also includes other insightful features. These include 45 mm faders; selectable +/-6dB or +/-15dB boost/cut range for precise gain adjustments; XLR, barrier strip, and 1/4'' TRS connectors for installation ease; balanced inputs and outputs for quiet operation; and chassis/signal ground lift capabilities for quick hum isolation. The visionary design of the dbx 12 Series makes your job easier.

The dbx 12 Series Equalizers were precision engineered to provide years of maintenancefree operation in any application. The magnetically isolated transformer, electronically balanced/unbalanced inputs and servo balanced/unbalanced outputs, RF-filtered inputs and outputs, and power-off hard-wire relay bypass with 2 second power up delay were steps our engineers took to ensure compatibility for all installations. Only the best components were utilized, yielding a 10Hz to 50kHz frequency response, greater than 90dB SNR (ref +4dBu), less than 0.005% THD +Noise (1kHz at +4dBu), and interchannel crosstalk of less than -80dB from 20Hz to 20kHz. All this attention to detail is contained in a 3U steel/aluminum chassis. ItÕs no wonder that dbx has been a leader in the industry for over 25 years.

18-1779-A 07/99

¥ Switchable Boost/Cut range between ±6dB and ±15dB

¥ Electronically balanced/unbalanced inputs

¥ Servo balanced/unbalanced outputs

¥ RF filtered 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 hardwire relay bypass with 2-second power-up delay

1231

+15

Graphic Equalizer

-15

+15

-15

RANGE

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

-6

+/-15

-6

+/-6

RANGE

+/-6

+/-15

CUT

+18+100-10

OUTPUT

LEVEL (dBu)

CLIP

LOW

+18+100-10

+12

GAIN

INPUT

-12

BYPASS

OUTPUT

LEVEL (dBu)

CLIP

CUT

LOW

+12

GAIN

INPUT

-12

BYPASS

1231

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 0dB. 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 frontpanel 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 an LED to indicate when the filter is active. 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 40k½ balanced and 20k½ 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 200½ balanced and 100½ unbalanced, and shall be capable of driving not less than +21dBu into 2k½ or greater and not less than +20dBm (into 600½) 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. THD+Noise shall be less than 0.005% 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 1231 Equalizer.

dbx engineers are constantly working to improve the quality of our products. Specifications are, therefore subject to change without notice.

FOR MORE INFORMATION CONTACT:

dbx Professional Products

8760 S. Sandy Pkwy.

Sandy, Utah 84070

Phone (801) 568-7660

Fax (801) 568-7662

IntÕl Fax (801) 568-7583

customer@dbxpro.com

http://www.dbxpro.com

A Harman International Company

Inputs

Connectors: 1/4" TRS, female XLR (pin 2

hot), and barrier terminal strip

Type: Electronically

balanced/unbalanced, RF filtered

Impedance: Balanced 40k½, unbalanced

20k½

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 terminal strip Type: Impedance-

balanced/unbalanced, RF

filtered Impedance: Balanced 200½, unbalanced

100½ Max Output Level: >+21dBu balanced/unbalanced

into 2k½ or greater

>+18dBm

balanced/unbalanced (into

600½)

System Performance

Bandwidth: 20Hz to 20kHz, +0.5/-1dB Frequency Response: <10Hz to >50kHz, +0.5/-3dB

+/-15dB range +/-6dB range

Dynamic Range: 109db 115db Signal-to-Noise: 90db 97db THD+Noise: <0.005%

Interchannel Crosstalk: <-80dB, 20Hz to 20kHz

Function Switches

EQ Bypass: Bypasses the graphic equalizer

section in the signal 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: 4-LED bar graph (Green,

Green, Yellow, Red) at -10, 0,

+10, and +18dBu EQ Bypass: 1 LED: red Clip: 1 LED: red Low Cut: 1 LED: red +/-6dB: 1 LED: yellow +/-15dB: 1 LED: red

Power Supply

Operating Voltage: 100VAC 50/60Hz, 120VAC

60Hz, 230VAC 50/60Hz Power Consumption: 1215 24W; 1231 24W Mains Connection: IEC receptacle

Physical

Dimensions: 1215: 3.5" H X 19" W X 7.9" D

(8.9cm x 48.3cm x 20.1cm)

1231: 5.25" H X 19" W X 7.9"

D (13.4cm x 48.3cm x 20.1cm) Weight: 1215: 8.5 lbs.

1231: 10.6 lbs. Shipping Weight: 1215: 9.5 lbs.

DUAL CHANNEL 31 BAND EQUALIZER

13610+18+100-10

+/-15

+/-6

RANGE

-6

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

+/-15

+/-6

RANGE

-6

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 SALT LAKE CITY, UTAH MADE IN USA MODEL 1231 GRAPHIC EQUALIZER  

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

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

CLIP

BYPASS

CLIP

BYPASS

POWER



24 WATTS



100V 50/60Hz

120V 60Hz



OUTPUT

LEVEL (dBu)

-120+12

INPUT

GAIN

OUTPUT

LEVEL (dBu)

-120+12

INPUT

GAIN

LOW

CUT

+18+100-10

LOW

CUT

OUTPUT INPUT

OUTPUT

INPUT

CONNECTOR POLARITY

PHONE:

XLR:

TIP

PIN 1

RING

PIN 2

SLEEVE

OUTPUT INPUT

PIN 3

OUTPUT

INPUT

INPUTOUTPUT

+15

-15

Graphic Equalizer

+15

-15

1231

¨