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Radial Engineering
JDI Duplex MK4 Stereo Direct Box (2014 Update)

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Item: N13-2840

Availability: Out of stock

JDI Duplex MK4 Stereo Direct Box (2014 Update)
JDI Duplex MK4 Stereo Direct Box (2014 Update) JDI Duplex MK4 Stereo Direct Box (2014 Update) JDI Duplex MK4 Stereo Direct Box (2014 Update)


Radial Engineering's JDI Duplex… the world's finest passive stereo direct box.

The Radial JDI Duplex is a full-feature, stereo passive direct box designed to enhance connectivity, reduce noise, and simplify the hectic life of the touring professional, broadcast engineer or AV integrator. It is plug-and-play easy to use while delivering the utmost sonic quality.

Like the Radial JDI, the Duplex employs two high-performance 'made in the USA' audio transformers and the same pristine audio signal path that has made the JDI the industry standard. It features exceptional signal handling with virtually zero phase shift or harmonic distortion, while remaining linear across the entire audio spectrum. When driven to extremes, the natural transformer saturation and resulting warm Bessel curve makes the Radial Duplex the perfect choice for smoothing out highly dynamic instruments such as digital pianos and electronic drums that can sound harsh when pushed. Transformer isolation provides the additional benefit of eliminating troublesome ground loops that can cause hum and buzz in the audio system or interfere with video displays.

This 'Swiss Army knife' DI is equipped with ¼' connectors for instruments, RCA connectors and a 3.5mm TRS for unbalanced -10dB consumer electronics plus XLR inputs for +4dB professional line sources. Radial's innovative book-end design provides protective zones on the front and rear to keep connectors and switches out of harm's way. The 14 gauge I-beam inner frame adds tremendous rigidity to eliminate outside stresses that could torque the PC board and cause premature solder joint and trace failure. The steel outer shell couples with the transformer's mu-metal shield to protect against stray magnetic fields from power transformers or lighting systems that could cause interference. Finally, a full-bottom no-slip pad works double-duty by providing both mechanical and electrical isolation. The Radial Duplex delivers outstanding connectivity, superlative audio and quiet dependable performance..


  • -10dB RCA connectors
  • +4db XLR inputs
  • Eclipse transformer-equipped passive DI
  • 100% isolation eliminates ground loops
  • Virtually zero phase & harmonic distortion
  • Exceptional signal handling
  • High common mode noise rejection
  • Stereo direct box for high output sources
  • Ultra linear response from 10Hz to 40kHz
  • Eliminates hum and buzz from ground loops


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  • Audio circuit type:  Passive, transformer based
  • Number of channels:  Dual channel (stereo)
  • Frequency response:  20Hz ~ 20KHz (± 0.2dB)  
  • Dynamic range:  135dB 
  • Maximum input:   +21dB @ 20Hz 
  • Total harmonic distortion:   0.05% from 20Hz ~ 20kHz @-10dB
  • Phase deviation:  0.3° @ 100Hz; 3° @ 20Hz 
  • Input impedance:  140k Ohms, unbalanced 
  • Output impedance:  150 Ohms, balanced 
  • Transformer:  Eclipse ET-DB1, 12:1 ratio
  • Shield:  Dual Faraday, mu-metal can
  • Input pad:   -15dB  
  • Merge:   Sums left & right sources to mono
  • 180° polarity reverse:   Inverts absolute phase
  • Ground lift:   Disconnects pin-1 at XLR output 
  • XLR configuration:   AES standard (pin-2 hot) 
  • Connectors:  1/4" in & thru, XLR-F in, XLR-M out
  • Construction:   14 gauge steel chassis & outer shell
  • Finish:  Baked enamel
  • Size:  (W x H x D)  89 x  51 x 139.7mm (3.5" x  2" x 5.5")  
  • Weight:   1kg (2.2lbs)
  • Shipping Size: W x H x D:  149 x 83 x 216mm(5.87" x 3.25" x  8.50")
  • Shipping Weight:  1.43 kg (3.15 lbs)
  • Power:   Passive, no power required 
  • Warranty:   Radial 3-year, transferable

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