ART HQ231 – Pro Dual Band EQ w/FDC (pre-owned)



ART HQ231 – Pro Dual Band EQ w/FDC (preowned)





The HQ231 Dual 31-band Graphic EQ is perfect for any live sound application where there is a high feedback potential including monitor mixes, side-fill cabinets or high powered front-of-house mixes situations​.

ART’s proprietary FDC™ within the HQ231 (Feedback Detection Circuitry – designed and developed by ART Engineering) instantly illuminates an LED on the corresponding EQ band fader with the greatest sustained signal. The LED indicators can immediately show which band corresponds to the feedback frequency, allowing the sound engineer to reduce gain in that band to quickly kill the feedback while having a minimal impact on the sound of the live program material.

Constant-Q Filtering helps the HQ’s FDC work with greater efficiency while offering superior overall performance of the EQ. Constant-Q ensures that even when making radical adjustments to a frequency band, that adjacent bands will not be affected. This is particularly critical in professional applications including monitor mixes and feedback control.

HQ231 Highlights:

  • ART’s proprietary FDC™ (Feedback Detection Circuitry – designed and developed by ART Engineering)
  • Constant-Q Filtering
  • 45mm center detent sliders with selectable boost or cut range of 6dB or 12dB for radical tone shaping, or precise control of a sound system.
  • Versatile connection to any live sound system or installation using balanced XLR, 1/4-inch TRS and Unbalanced RCA input and output jacks
  • High and low pass filters, analog level metering
  • Variable input level controls
  • Signal clip level indicators
  • Ground lift switch
  • Internal power supply and selectable line voltage

Key Features

  • FDC™ Feedback Detection Circuit
  • Dual Channel 31-Band Graphic Equalizer
  • Output Level VU Metering on Each Channel
  • Constant-Q Filtering
  • Individual High and Low Pass Filters on Each Channel
  • Center-Detented Frequency Band Sliders
  • Independent Level and Bypass Controls on Each Channel
  • Relay Bypass – If Power is Lost, Signal Will Still Pass
  • Variable Input Controls
  • Signal Clip Level Indicators
  • Ground Lift Switch
  • Internal Power Supply
  • Selectable Line Voltage


Filter Type Constant Q -3% center accuracy
Frequency Bands 2 x 31, 1/3 octave, ISO spacing
Frequency Response 20Hz- 20kHz, +/-0.5dB
Indicators OUTPUT NOISE: -94dBm (unweighted)
Input Impedance 20K Ω typical
Input/Output Connections Active balanced XLR and 1/4″ TRS, Unbalanced RCA
Maximum Input Level +22dBm
Maximum Output Level +22dBm
Power (Switchable) 95-125 VAC, 50/60Hz, 190-250 VAC, 50Hz
Range +/-6dB or +/-12dB selectable
Total Harmonic Distortion .01% (20Hz-20kHz+10 dBu )
Dimensions 7.5″ d x 19.0″ w x 3.5″ h
Weight 12 lbs