Sonifex RB-LU4 Quad Stereo Balanced to Unbalanced Converter
The Sonifex RB-LU4 is a 1U rack-mount quad stereo unit for interfacing professional balanced line levels to domestic or semi-pro unbalanced equipment, e.g. for connecting a pro satellite receiver to a consumer
hi-fi system. All connections are on the rear panel. The eight balanced XLR-3 inputs have an impedance of 20kΩ and are routed to eight unbalanced RCA outputs with an output impedance of <50Ω.
The output gain can be individually adjusted for left and right channels by using pre-set potentiometers accessible through the rear panel. A LED power indicator on the front panel displays the power supply connection.

RB-LU4 Block Diagram.
Technical Specification For RB-LU4
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Audio Specification
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| Maximum Input Level: |
+28dBu |
| Input Impedance: (XLR) |
>20kΩ balanced bridging |
| Output Impedance (RCA): |
<50Ω |
| Maximum Output Level: |
+22dBu |
| Distortion: |
0.01% THD @ 1kHz, ref +8dBu output |
| Noise: |
-100dB, unity gain, ref +8dBu output |
| Common Mode Rejection: |
>66dB typically |
| Frequency Response: |
20Hz to 20kHz ±0.1dB (600Ω load, ref 1kHz) |
| Gain Range: |
Unbalanced Output : -28dBu to 0dBu, ref 0dBu into balanced XLR input |
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Connections
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| Inputs: |
8 x XLR 3 pin female (Balanced) |
| Outputs: |
8 x RCA phono (Unbalanced) |
| 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) |
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Equipment Type
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| RB-LU4: |
Quad stereo balanced to unbalanced converter |
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Physical Specification
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| Dimensions (Raw): |
48cm (W) x 10.8cm (D) x 4.2cm (H) (1U)
19” (W) x 4.3” (D) x 1.7” (H) (1U) |
| Dimensions (Boxed): |
58.5cm (W) x 22.5cm (D) x 7cm (H)
23” (W) x 8.9” (D) x 2.8” (H) |
| Weight: |
Nett: 1.3kg Gross: 1.9kg
Nett: 2.9lbs Gross: 4.2lbs |