Product Overview

The DBX 1231 is a professional dual 31-band graphic equalizer from the 12 Series, designed for installed sound systems requiring high dynamic range and flexible connectivity in a single rack unit. As a 2-channel 31-band graphic EQ with XLR and barrier strip inputs, the 1231 provides ISO-centered 1/3-octave frequency control on two independent channels housed in a 3U chassis. Audio contractors specify the DBX 1231 graphic equalizer for commercial AV installations because of its magnetically isolated transformer balanced I/O, relay bypass protection, and broad connector compatibility including XLR, TRS, and barrier strip terminals. Available at Creation Networks.

Product Description

The DBX 1231 delivers dual-channel 31-band graphic equalization in the rugged 12 Series format. Each channel provides 31 ISO-centered 1/3-octave bands across the full audio frequency range, with individual faders operating at a selectable +12 dB or +6 dB boost/cut range. The switchable range allows precision room correction at +6 dB or more aggressive voicing at +12 dB without hardware changes. An 18 dB/octave Bessel low-cut filter at 40 Hz removes sub-bass content that can cause intermodulation distortion in program amplifier chains. Magnetically isolated transformer balanced inputs and outputs provide exceptional common-mode rejection and galvanic isolation, making the 1231 well suited for installations with long cable runs or ground loop exposure. Relay bypass engages automatically if the unit loses power, ensuring the signal path remains active even during power interruptions. XLR, 1/4 inch TRS, and barrier strip terminals on both input and output accommodate a wide range of permanent installation wiring configurations without adapters. The 1231 occupies 3U of rack space and delivers greater than 118 dB dynamic range at unity gain, with THD+Noise less than 0.003% at +4 dBu and 1 kHz. These performance figures meet the technical requirements of commercial-grade installed sound systems in large venues.

Key Features

• Dual 31-Band 1/3-Octave Graphic EQ – Two independent channels with ISO-centered frequency bands spanning the full audio range.
• Magnetically Isolated Transformer Balanced I/O – Provides galvanic isolation and high CMRR for installations with long cable runs or grounding issues.
• Selectable Boost/Cut Range – Switch between +6 dB and +12 dB per band to match the precision or correction depth required by the installation.
• 18 dB/Octave 40Hz Bessel Low-Cut Filter – Removes sub-bass energy before it reaches the amplifier chain to reduce intermodulation distortion.
• Relay Bypass – Automatically bypasses the unit signal path during power-off events to maintain audio continuity.
• Flexible Connector Options – XLR, 1/4 inch TRS, and barrier strip terminals on all inputs and outputs for permanent installation wiring flexibility.
• Greater Than 118 dB Dynamic Range – High dynamic range at unity gain supports professional-grade signal chains without added noise.
• 3U Rack Format – Standard 19-inch rack mounting in a 3U chassis appropriate for equipment racks in installed venues.

Typical Applications

• House of worship
• Auditorium
• Multi-purpose room
• Performing arts center
• All-hands room
• Training room

Technical Specifications

Frequently Asked Questions

Why does the DBX 1231 use a 3U chassis instead of the more common 2U format?The 12 Series format uses larger 45mm faders compared to the 2 Series 30mm faders. The additional fader travel improves resolution and tactile feel for fine adjustments, which is a priority in permanent installed sound applications where settings may rarely change but precision matters when they do.What is the benefit of magnetically isolated transformer balanced I/O on the 1231?Transformer isolation provides galvanic separation between the input and output, which eliminates ground loops that would otherwise introduce 60 Hz hum in permanent installations with long cable runs between equipment racks and stage boxes or amplifier locations. The transformers also provide high common-mode rejection across a wide frequency range.Can the DBX 1231 be used with a control system for remote bypass?The relay bypass function on the 1231 is designed as a power-fail protection feature and is not independently controlled via a remote logic input. Integration with a third-party control system for bypass would require a relay switching interface in the signal path external to the unit.What is the difference between the DBX 1231 and the DBX 231s?The 1231 is from the 12 Series and includes transformer balanced I/O, larger 45mm faders, barrier strip connector options, and a 3U chassis. The 231s is from the 2 Series and uses electronically balanced I/O, 30mm faders, and a 2U chassis. The 1231 is typically specified for permanent installations where transformer isolation is required; the 231s is more commonly used in touring and portable applications.Does the DBX 1231 include a pink noise generator?The DBX 1231 does not include a built-in pink noise generator. Room correction with the 1231 requires an external pink noise source and a real-time analyzer. The DBX DriveRack series products include built-in pink noise generation and AutoEQ for fully integrated room correction without external tools.Is there a front-panel bypass switch on the DBX 1231?Yes. The 1231 includes a front-panel EQ bypass switch that routes the signal around the equalizer section while maintaining the relay bypass protection for power-off events.