DBX 1231 Dual 31-band graphic equalizer

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 low-cut filters, but also includes other insightful features.
These include 45 mm faders; selectable +/-6 dB or +/-15 dB 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 maintenance-free 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 10 Hz to 50 kHz frequency response, greater than 90 dB SNR (ref +4 dBu), less than 0.005% THD +Noise (1 kHz at +4 dBu), and interchannel crosstalk of less than -80 dB from 20 Hz to 20 kHz.
All this attention to detail is contained in a 3U steel/aluminum chassis.

- Switchable boost/cut ranges of ±6 or ±15 dB
- Electronically balanced/unbalanced inputs
- Servo balanced/unbalanced outputs
- RF filtered inputs and outputs
- XLR, Barrier Strip, and 1/4" TRS connectors
- -12 dB/+12 dB input gain range
- 18 dB/octave 40 Hz Bessel low-cut filter
- Chassis/signal ground lift capability
- Internal power supply transformer
- Power-off hardwire relay bypass with 2-second power-up delay

INPUT

Connectors:
1/4" TRS, female XLR (pin 2 hot), and barrier terminal strip
Type:
Electronically balanced/unbalanced, RF filtered
Impedance:
Balanced 40 kohm, unbalanced 20 kohm
Max Input Level:
>+21 dBu balanced or unbalanced
CMRR:
>40 dB, typically >55 dB at 1 kHz

OUTPUTS

Connectors:
1/4" TRS, male XLR (pin 2 hot), and barrier terminal strip
Type:
Impedance-balanaced/unbalanced, RF filtered
Impedance:
Balanced 200 Ohm, unbalanced 100 Ohm
Max Output Level:
>+21 dBu balanced/unbalanced into 2 kohm or greater
>+18 dBm balanced/unbalanced (into 600 Ohm)

SYSTEM PERFORMANCE

Bandwidth:
20 Hz to 20 kHz, +0.5/-1 dB
Frequency Response:
50 kHz, +0.5/-3 dB
+/-15 dB range
+/-6 dB range
Dynamic Range:
109 dB
115 dB
Signal-to-Noise:
90 dB
97 dB
THD + Noise:
Interchannel Crosstalk:

FUNCTION SWITCHES

EQ Bypass:
Bypasses the graphic equalizer section in the signal path
Low Cut (recessed):
Activates the 40 Hz 18 dB/octave Bessel high-pass filter
Range (recessed):
Selects either +/- 6 dB or +/- 15 dB slider boost/cut range

INDICATORS

Output Level Meter:
4-LED bar graph (Green, Green, Yellow, Red) at -10, 0, +10, and +18 dBu
EQ Bypass:
1 LED: Red
Clip:
1 LED: Red
Low Cut:
1 LED: Red
+/-6 dB:
1 LED: Yellow
+/-15dB:
1 LED: Red

POWER SUPPLY

Operating Voltage:
100 VAC 50/60 Hz, 120 VAC 60 Hz
230 VAC 50/60 Hz
Power consumption:
24 W
Main Connection:
IEC receptacle

PHYSICAL

Dimensions:
5.25" H X 19" W X 7.9" D (13.4 m x 48.3 cm x 20.1 cm)
Weight:
10.6 lbs