Radial Engineering JDI Passive DI Box

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The World’s Finest Passive DI

The Radial JDI is a high performance passive direct box designed for professional concert touring and studio recording. Built around a premium Jensen transformer, it delivers exceptional audio performance and is the industry's go-to solution for capturing the true character of any instrument. The JDI is designed to handle extreme signal levels without distortion of any kind.

Jensen Transformer

The JDI is built around a high quality Jensen JT-DB-EPC audio transformer. Jensen transformers are renowned for their ability to gracefully handle transients, delivering a smooth, warm Bessel curve. Ruler flat from 10Hz to 40kHz with virtually zero phase deviation. The result is the pure, natural sound of the instrument with no artefacts.

Passive vs Active Circuit

Unlike an active DI that is limited by its rail voltage and clips hard when overloaded, a transformer saturates gracefully. When you push a Jensen transformer hard it naturally rounds out the transient, acting more like a soft limiter than a hard clip. The JDI requires no power whatsoever: the transformer performs both high-to-low impedance conversion and signal balancing simultaneously, passing signal while rejecting stray DC voltage. This passive design makes it particularly effective at eliminating hum and buzz caused by ground loops, and means it works on any stage or studio setup without phantom power or batteries.

Being a passive DI, the Radial JDI manages impedance conversion and signal balancing over an isolated magnetic bridge. This bridge passes the pure instrument signal while filtering out stray DC voltage that causes noise. This makes the JDI particularly good at eliminating hum and buzz caused by ground loops.

Radial JDI Features:

• Jensen JT-DB-EPC transformer equipped passive DI
• No power required, no batteries, no phantom power
• Ruler flat 10Hz to 40kHz, virtually zero phase deviation
• Smooth transformer saturation on transients rather than hard clipping
• 100% isolation eliminates ground loops
• Mu-metal transformer shielding
• Speaker tap for direct connection to amp speaker outputs
• Merge switch, stereo to mono
• -15dB pad
• Ground lift
• 1/4" instrument input with thru output
• Balanced XLR output