Radial JDI Stereo: The World's Finest Passive Stereo Direct Box for Instruments

The Radial JDI Stereo is a two-channel passive stereo direct box equipped with two Jensen JT-DBE transformers, built to deliver the pure, unaltered sound of stereo instruments to the stage and studio. It is the stereo evolution of Radial's legendary mono JDI, sharing the same transformer-based signal path in a dual-mono design purpose-built for keyboards, synths and stereo acoustic rigs. For the touring keyboardist and the recording engineer who refuse to compromise on tone, the JDI Stereo is the box that captures an instrument's true voice and carries it, dead quiet, all the way to the console.

What a Passive Direct Box Does for a Stereo Instrument

A direct box converts the high-impedance, unbalanced output of an instrument into a low-impedance balanced signal that can run long cables to the mixer without picking up noise, and it isolates grounds to eliminate hum. Stereo instruments produce a left and a right channel, and to preserve the width and depth the player hears on stage, both channels must be handled identically. The JDI Stereo provides two matched, fully independent passive channels, so a stereo keyboard or dual-source acoustic rig arrives at the console balanced, isolated and perfectly imaged.

Jensen JT-DBE Transformers: True to the Music

Each channel is built around a Jensen JT-DBE transformer, and these are the reason the JDI Stereo sounds the way it does. Every transformer uses a unique nickel core stack and a proprietary winding technique, with dual Faraday shields to eliminate high-frequency noise and a MuMETAL outer can that protects against external magnetic fields. The payoff is exceptionally low distortion of every type together with the ability to handle extreme transients at any frequency, so the delicate detail of a piano patch or the punch of a synth bass passes through completely intact.

Reference-Grade Performance You Can Measure

The numbers back up the sound. The JDI Stereo delivers a frequency response of 20 Hz to 20 kHz within a remarkable 0.2 dB, a 135 dB dynamic range, and total harmonic distortion of just 0.05% across the audio band. Phase deviation is held to 0.3° at 100 Hz, and the box accepts up to +21 dB of input before overload. These are reference-instrument figures, which is why the JDI Stereo is trusted on the world's biggest stages and in its finest studios to pass a signal without adding a fingerprint of its own.

Pad, Ground Lift and a Thru for Stage Flexibility

Practical switching makes the JDI Stereo easy to deploy. A -15 dB input pad handles hot keyboard and line-level outputs so the transformers never see too much level. A ground lift breaks the loop between the instrument rig and the console to silence hum. And each channel offers a 1/4-inch thru jack alongside its XLR output, so you can send a balanced feed to the front-of-house console while keeping a local unbalanced signal running to a stage amp or monitor at the same time.

Road-Ready Construction That Lasts a Career

Fully passive, the JDI Stereo needs no power, no battery and no phantom, so it can never clip from a dying battery or add electronic noise. Its heavy-duty steel shell and internal I-beam construction protect the transformers and circuitry through the roughest touring, and Radial builds it to work dependably for years in the harshest environments. This is gear you buy once and rely on for a lifetime of shows and sessions.

Who the Radial JDI Stereo Is For

The JDI Stereo is for touring and session keyboardists running stereo pianos, synths and workstations, for engineers capturing stereo acoustic instruments and playback, and for anyone who wants the purest possible passive path from a stereo instrument to the console. If your instrument speaks in stereo and every nuance matters, the JDI Stereo is the direct box that lets it be heard exactly as intended.