dbx 131S - Digital Zone Processor

dbx 131s - 31-band (1/3 octave) graphic equalizer with 50Hz low cut and LED meters

The dbx 131s is a professional 31-band ( 1/3-octave step) Constant Q graphic equalizer that delivers precise, predictable control in sound reinforcement, studio, and installation applications. It features ±12 dB of input gain , ±6 dB / ±12 dB EQ range select per band, a 50 Hz (12 dB/oct) Low Cut filter for clean sub-bass, and a panel bypass for instant comparison. Non-conductive 20 mm faders allow for fine adjustments, while 4-segment LED meters make output level monitoring easy. With balanced XLR and 1/4" TRS inputs and outputs, a frequency response of <10 Hz to >50 kHz , and a dynamic range of >108–112 dB , the 131s combines road-worthy reliability and high-level sonic performance in a 1U rackmount footprint.

Main features

• 31 bands, 1/3 octave with Constant Q for precise cuts/boosts throughout the fader travel.
• Switchable boost/cut range : ±6 dB (fine adjustments) or ±12 dB (coarse corrections).
• Low Cut at 50 Hz (12 dB/oct) to control headings and infra-lows.
• Adjustable input gain ±12 dB ; EQ section bypass from the front panel.
• Measurement with 4-segment LED at the output to avoid saturation.
• Professional connections : XLR and 1/4" TRS (balanced) inputs/outputs.
• Audio performance : <10 Hz–>50 kHz (+0.5/−3 dB), THD+N <0.003% , DR typ. >112 dB , crosstalk < −90 dB.
• Rugged and reliable 1U construction for touring and fixed installation.

Product benefits

• Musical and consistent control : The Constant Q curve maintains selectivity when varying the cut/boost level.
• Instant versatility : Switch between ±6 and ±12 dB depending on whether you need fine tuning or aggressive correction.
• Easy integration : Balanced XLR/TRS I/O, 1U height, and clear controls for engineers and front-of-house staff.
• Clean sound : Low Cut at 50 Hz and low THD+N to maximize clarity and intelligibility.

Use cases

• Live PA : room/monitor equalization, resonance elimination and feedback control.
• Study : Quick correction of near-field monitors or outboard chains.
• Commercial installation : fine-tuning of systems in bars, theaters, auditoriums or temples.

Frequently Asked Questions

• What differentiates the 131s from a parametric EQ? The 131s offers 31 fixed 1/3-octave bands with faders; a parametric EQ allows you to choose frequency/Q per band. For quick room adjustments, the graph is more visual.
• Does the Low Cut affect all bands? Yes, it's a global high-pass filter at 50 Hz (12 dB/oct) applied to the signal.
• Can I use it as an insert or between the mixer and the power amp? Yes; its maximum output of > +21 dBu and balanced I/O allow for both topologies.

Description for projects

dbx 131s Graphic Equalizer ; 1-channel, 31-band (1/3-octave) with Constant Q ; ±6/±12 dB Boost/Cut Range; ±12 dB Input Gain ; 50 Hz Low Cut (12 dB/oct); EQ Bypass ; 20 mm Sliders Balanced XLR (female) and 1/4" TRS inputs (40 kΩ bal./20 kΩ unbal., max. >+21 dBu, CMRR > 40 dB); XLR (male) and TRS outputs (100 Ω bal./50 Ω unbal., max. >+21 dBu at ≥2 kΩ; >+18 dBm at 600 Ω); performance: 20 Hz–20 kHz +0.5/−1 dB ; <10 Hz–>50 kHz +0.5/−3 dB ; DR typ. >112 dB , THD+N <0.003 % , crosstalk < −90 dB; power supply 100–240 V~ 50/60 Hz (IEC), consumption 15 W ; 1U rack format ; dimensions 44.5 × 482.6 × 152.4 mm (H × W × D); weight 2.2 kg (shipping 2.8 kg).