Radial ProDI

The Radial ProDI is a full-range passive mono direct box that converts instrument signals to balanced, low-impedance outputs for your mixer, with no power required. Its custom isolation transformer eliminates hum-causing ground loops while preserving natural tone, and Radial’s rugged steel construction makes it a long-lasting workhorse for acoustic guitar, bass, keyboards, and more, on stage and in the studio.

Highlights

• Full-range passive mono direct box
• Custom transformer provides 100% isolation from ground loops
• Very low harmonic and phase distortion
• -15 dB pad and ground lift switch
• 1/4-inch input and thru, balanced XLR output
• 14-gauge steel I-beam frame with book-end design

Radial ProDI: Simple, Quiet, and Built to Last

Passive DIs use a transformer instead of active electronics, so they need no batteries or phantom power and naturally reject noise. The ProDI’s custom transformer handles strong signals without saturation and keeps phase distortion extremely low in the bass and midrange, so instruments sound full and natural.

Eliminate Hum and Buzz

The transformer provides 100% isolation between the instrument and the console, breaking ground loops that cause hum. Isolated XLR connectors and a military-spec circuit board with a full ground plane reduce susceptibility to RF noise, and a ground lift switch solves stubborn hum problems.

Setting Up the ProDI

Connect your instrument to the 1/4-inch input, connect the 1/4-inch thru jack to your stage amp if needed, and run an XLR cable from the output to your mixer or stage box. If the signal distorts, engage the -15 dB pad; if you hear hum, press the ground lift switch.

What to Pair With the ProDI

Pair the ProDI with quality instrument and XLR cables, a mixer or stage box, and a Radial ProD2 for stereo sources such as keyboards and playback devices.

Great for Acoustic Instruments and Keyboards

With acoustic guitars and basses, the ProDI lets the instrument’s natural tone shine through with a smooth, musical sound. With keyboards and electronic instruments, it quickly removes ground loops while preserving dynamics.

Built Radial Tough

A 14-gauge welded I-beam inner chassis prevents torque stress on the circuit board, the book-end outer shell protects switches and connectors, and a full no-slip rubber pad provides electrical insulation and keeps the DI in place.

Passive vs. Active DI

Active DIs use electronics powered by batteries or phantom power and often suit passive pickups with low output. Passive DIs like the ProDI need no power and excel with active pickups, keyboards, and line-level sources, offering simplicity and excellent noise rejection.

Why Use a DI Box?

Instruments produce high-impedance, unbalanced signals that lose tone and pick up noise over long cables. A DI converts them to balanced, low-impedance signals that travel cleanly to the mixer, matches levels to the mic preamp, and isolates the stage from the console to stop ground loops.

Tips for Best Results

Use the shortest practical instrument cable between the instrument and the ProDI, and keep the long XLR run between the DI and the mixer. Start with the pad off and engage it only if you hear distortion, and try the ground lift whenever hum appears.

Radial ProDI FAQ

Does it need power? No. It’s fully passive and needs no batteries or phantom power.

Is it mono or stereo? Mono. For stereo sources, choose the Radial ProD2.

Radial ProDI Specifications at a Glance

• Type: passive mono direct box
• Transformer: custom isolation transformer
• Input: 1/4-inch with 1/4-inch thru
• Output: balanced XLR (pin-2 hot)
• Controls: -15 dB pad, ground lift
• Construction: 14-gauge steel I-beam

Who Buys the Radial ProDI

• Acoustic guitarists and bassists
• Keyboard players
• Churches and schools
• Live sound and rental companies

Why Buy the Radial ProDI From Metro Sound & Lighting

Metro Sound & Lighting isn’t a catalog-only retailer. We design, install, and service sound systems in-house, so our team can help you build a quiet, reliable stage setup and support it after the sale. We offer B2B and integrator pricing for churches, schools, and venues.

Browse more options in our Direct Boxes category, or see the full specifications on the official Radial ProDI product page.