Sonifex RB-UL4
Redbox Quad Stereo Unbalanced-Balanced Converter


Our Price: $550.00
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Sonifex's RB-UL4 is a 1RU rack-mount quad stereo unit for interfacing domestic or semi-professional unbalanced equipment to professional balanced line levels.

All connections are on the rear panel.  The eight RCA unbalanced inputs have an impedance of 10kOhm and are routed to eight balanced XLR-3 outputs with an output impedance of <50 ohms.  The output gain can be individually adjusted for left and right channels by using pre-set potentiometers accessible through the rear panel.

Audio Specifications:

  • Maximum Input Level: +28dBu
  • Maximum Output Level: +28dBu
  • Input Impedance: >10kOhm
  • Output Impedance: <50 ohms
  • Distortion: 0.01% THD @ 1kHz, ref +8dBu output
  • Noise: -100dB, unity gain, ref +8dBu output
  • Frequency Response: 20Hz to 20kHz ┬▒0.1dB (600 ohm load, ref 1kHz)
  • Gain Range: Balanced output : -15dBu to +15dBu, ref -15dBu into unbalanced RCA input


  • Inputs: 8x RCA phono (Unbalanced)
  • Outputs: 8x 3-pin XLR-M (Balanced)
  • Mains Input: Filtered IEC, switchable 110-120V, or 220-240V, fused, 6W max
  • Fuse Rating:
    • Anti-surge fuse 100mA 20 x 5mm (230VAC)
    • Anti-surge fuse 250mA 20 x 5mm (115VAC)

Physical Specifications:

  • Dimensions (Raw): 19" W x 4.3" D x 1.7" (1 RU) H (48 x 10.8 x 4.2 cm)
  • Dimensions (Boxed): 23" W x 8.9" D x 2.8" H (58.5 x 22.5 x 7 cm)
  • Weight:
    • Net: 2.9 lbs (1.3 kg)
    • Gross: 4.2 lbs (1.9 kg)
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