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Compact metal passive direct box with rubber base

Radial Engineering

Radial Engineering RAD-PRODI Passive Direct Box

SKU CH-3FMS-JY3P7

Single-channel passive direct box with custom transformer, -15dB pad and ground-lift switch for acoustic guitar and bass

  • Recording TypeVideo Recorder
  • Custom transformer eliminates noise for clean signal
  • 15dB pad handles high-output sources without distortion
  • Ground lift switch removes ground-loop hum instantly
  • Passive design needs no external power for simple setup
  • Rugged 14-gauge I-beam chassis withstands stage abuse

Single-channel passive direct box

The Radial Engineering RAD-PRODI is a single-channel passive direct box built for acoustic guitars and bass guitars. It suits live sound and studio work where a clean, balanced signal is needed without external power. Musicians and engineers who want transformer isolation in a compact unit will find it practical. It is not for users needing active buffering or multi-channel routing.

Transformer headroom and pad

A custom-wound transformer delivers an exceptionally linear response from 20Hz to 18kHz and handles high signal levels without saturation. A -15dB pad accommodates hotter sources such as active pickups or line-level devices. The passive design adds no noise of its own but cannot boost a weak instrument signal. Users requiring gain or impedance matching for very low-output sources must look elsewhere.

Rugged chassis and ground lift

A 14-gauge welded I-beam inner chassis and outer shell protect the circuit board from torque stresses. A full-bottom no-slip rubber pad provides electrical insulation and keeps the box stationary on stage or desk. A ground lift switch breaks ground loops to eliminate hum. The unit has no rack ears or mounting holes, so permanent installation requires an external tray or shelf.

Highlights

  • Custom transformer eliminates noise for clean signal
  • 15dB pad handles high-output sources without distortion
  • Ground lift switch removes ground-loop hum instantly
  • Passive design needs no external power for simple setup
  • Rugged 14-gauge I-beam chassis withstands stage abuse

Specifications

Recording TypeVideo Recorder

Questions about this item

Will the ProDI's passive design work with the piezo pickup on my older acoustic guitar without needing a battery or power supply?

Yes, the passive circuit requires no external power, so it connects directly to a piezo pickup and sends a balanced mic-level signal to the mixer.

How can I confirm the custom-wound transformer is delivering the specified 20Hz to 18kHz response after I connect it?

Run a frequency sweep from a test source through the ProDI and measure the output; the response should stay linear across the 20Hz to 18kHz range with very low harmonic and phase distortion.

Does the box include the 14-gauge welded I-beam chassis and no-slip rubber pad, or are those separate accessories?

The 14-gauge welded I-beam inner chassis and full-bottom no-slip rubber pad are built into the unit; nothing extra is needed for mounting or shock protection.

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