Skip to content

Radial HDI Studio Grade Single-Channel Active Instrument DI Direct Box


Radial HDI Studio Grade Single-Channel Active Instrument DI Direct Box


Manufacturer's Description

High Definition Studio Direct Box

The HDI is a studio-quality direct box designed to create exceptional recordings with any instrument, utilizing premium Jensen transformers and a unique Color control that provides an entirely new yet familiar-sounding sonic palette to experiment with.


  • Dial in an amazing tone within seconds
  • Blend from ultra-clean to amp-like distortion
  • Smooth Opto compressor for peak reduction
  • Mic and line-level outputs
  • Oversized custom-wound Jensen transformer

Instant Gratification

Despite the complex circuitry housed within the unit, the HDI has an elegant set of controls that allows the musician or engineer to dial up a record-ready sound with a minimal amount of tweaking required. The Level control drives the inputs of the HDI with instant visual feedback from the responsive front panel meter, while the Color knob provides seamless blending between an ultra-clean tone and amp-style distortion and saturation, so you can add just the right amount of character and grit to your instrument. A smooth Opto compressor can be engaged to control the peaks of the input signal, and a High-Pass Filter clears up any excessive low frequencies added by the Color control. Lastly, a Presence control accentuates the highs and high-mids, providing the ability to cut through the mix with results that are sure to impress.

Looks and Personality

With its gunmetal anodized 1/4"" thick milled front panel and distinctive styling reminiscent of classic outboard studio equipment, the HDI is sure to turn heads in any recording space. A custom output meter provides a level check at a glance, with oversized chrome knobs for precise adjustments and easy tweaking on-the-fly. The HDI is a stunning standalone unit, but it also comes complete with mounting hardware to install in standard 19"" equipment racks. One or two HDI's can be installed side-by-side in a 2RU rack space, and like all Radial products, they are built with rugged components and designed to easily withstand the rigors of concert touring.

Behind the Design

While the HDI is incredibly easy to use - requiring only a few seconds to achieve great-sounding results - both the design philosophy and the under-the-hood processes at work are anything but simple. Click here to read an interview with the HDI's designer, W.C. ""Hutch"" Hutchison for an in-depth look at how the HDI came to be and what makes its circuitry so unique.


Using the HDI alongside an amplifier

Record bass directly from the HDI while also feeding the unbuffered Thru output to a mic'd up amplifier to blend the two signals together. The HDI sounds so good on its own you just might mute the amp track altogether.

Using the HDI on acoustic guitar

The HDI pairs well with any instrument - with acoustic guitar it can add additional body and character that other direct boxes may lack. Take the line-level XLR output directly to your recording interface to bypass the need for any additional preamps in the signal path.

Using the HDI Processed Output

The HDI can be simultaneously used as a DI and as an instrument preamp, providing additional gain, saturation, and distortion before feeding the affected signal through to a clean amp or an amp modeling system.

Using the HDI with modular synthesizers

A dedicated Synth Input has a lower sensitivity to accommodate the hot outputs of modular synths or even other studio outboard equipment, allowing you to use the HDI to process any instruments or tracks you can think of.