Radial JDI Duplex Stereo Passive Direct Box

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Product Description

Radial JDI Duplex is a two channel direct box for stereo keyboards, stereo iPODs, mixers, recorders, guitar or bass rigs.The Duplex is a full-featured passive DI designed to enhance connectivity for the touring professional and AV integrator. The Duplex comes equipped with 1/4 inch connectors for -10dB consumer electronics and XLR inputs for +4dB professional line sources.

Each Duplex channel employs the same high-performance Jensen audio transformer as the industry standard Radial JDI direct box and has the same pristine audio signal path with virtually zero phase, harmonic and linear distortion. Natural transformer saturation and warm Bessel curve makes the Radial Duplex the perfect choice for rounding out highly dynamic instruments, like digital keyboards, that can sound harsh when driven hard. Transformer isolation also provides the benefit of eliminating troublesome ground loops that can cause hum and buzz and can interfere with video displays.

Radial's innovative book-end design provides protective zones that shield connectors and switches from the abuses of professional touring . A welded I-beam inner frame is designed to eliminate outside stresses that could torque the PC board and cause premature solder point and trace failure. A 14-gauge steel shell couples with the mu-metal transformer shield to eliminate stray magnetic field interference from power transformers and a full-bottom no-slip pad provides plenty of stay-put and helps reduce electrical coupling from amplifier chassis hardware.

The Radial JDI is considered by many to be the world’s finest direct box.

The Radial JDI is Jensen Transformer equipped, high quality passive direct box that has the advantage of providing complete isolation for reduced noise. The exceptionally low phase distortion, almost perfect linear response and low harmonic distortion make the JDI a superb choice for critical recording or live performance. The rugged construction allows the JDI to be used in the most abusive environments without concern for damage. The Radial JDI Duplex is ideal for acoustic guitars, bass, and keyboards.

warning WARNING: Cancer and Reproductive Harm -

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Helpful Info about the Manufacturer
Phone:  604-942-1001 Warranty:  3 Year Transferrable

Product Specifications

Product Specifications


  • Type: Passive Jensen Transformer equipped
  • Input Impedance: Unbalanced 140k-Ohms typical
  • Output Impedance: Balanced 150 Ohms typical
  • Frequency Response: 10Hz to 40kHz
  • Linear Performance: < -0.22 dBr deviation @20kHz
  • Total Harmonic Distortion: 0.05% @ 20Hz, 0.005% @ 1kHz
  • Phase Distortion: < 4º at 20Hz, 0.3º at 1kHz
  • CMR: 100dB @ 60Hz
  • Maximum Input Level: +22dBu
  • Size: 3.5 inches wide, 2 inches high, 5.5 inches deep
  • Weight: 2.2 lbs (1kg)
  • Construction: Welded 14-gauge steel
  • Finish: Baked enamel

Customer Reviews

Review: Mike H. from Round Rock, TX Submitted: 5/25/2014

Product Rating5 out of 5 stars.

verified buyer


HUGE improvement
Product Rating

Your general opinion of this product.

I was experiencing some hum and buzz in my 1/4" patchbay that I finally traced to my MPC 2000XL. I was under the previous assumption that the MPC had balanced TRS out but I was wrong. After adding the JDI Duplex in between not only is the impedance matched but I have a balanced signal that I can feed into my pre amp of choice. I no longer experience the annoying 60Hz noise. I plan on purchasing another one of these for my Roland XV-3080 soon. Love it!

I'm using this for home studio use but I could see how this would have no problem on stage. The thing is built like a tank - and heavy! It also contains very high quality Jensen transformers which apparently are highly sought after.

Virtually plug and play. High impedance instrument in to low impedance balanced mic out.

There are a variety of other features such as ground lift, phase reverse, 15dB pad as well as the option to feed +4dBu signals such as a CD or DAT player and have it then come out mic level. Also instrument thru as well.

The sound is absolutely transparent. What you put in is what you get out. With that being said I would imagine you could "color" the sound slightly by pushing the transformers a bit by feeding more gain on the inputs but I have not heard a huge difference upon doing so thus far. (Just my personal observation)

Review: Marvin Submitted: 2/25/2013

Product Rating5 out of 5 stars.


Clear Smooth Sound

Solid and Sturdy

Option to connect with amp or mixer simultaneously

Easy set up and operation

Very clear

Your general opinion of this product.

Recommend this product especially if you have high quality equipment

Review: Audio Engineer from Chicago Submitted: 1/24/2011

Product Rating4 out of 5 stars.


Engineer's Toolbox "Must Have"

I like that I can plug phono (RCA) type components directly into this D.I. I LOVE the Jensen Transformer!

No matter what's your experience in audio,Radial Engineering did there Job in making this Product extremely easy to use. If there's any doubt check out the 1 page Quick Start guide included with the Duplex D.I.

I use the Duplex in my studio and in Live Sound performances every week. This D.I. adds body and depth. It also takes away the harshness that digital components adds to audio.


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