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Radial Engineering HDI High Definition Studio Direct Box


In stock
Weight:  5.00
Retail Price: $1,140.00
Our Price: $949.99

Or pay $79.17/mo. Financing options

South Austin
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North Austin
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High Definition Studio DI

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.

Standard ¼” TS input for mono instruments. When in use this input overrides the rear-panel ¼” Input.

¼” TS unbuffered pass-through to feed the input of a stage amplifier.

Adjusts the input impedance at the 1/4” inputs, similar to an older amplifier with HI and LO inputs. Lower position is 200k Ohms, higher position is 2Meg Ohms.

Input level control which also allows you to drive the distortion channel of the Color control for greater saturation and coloration.

3-position switch controls an internal opto compressor circuit, providing smooth and natural dynamic control when the Color knob is set to the clean channel (7 o’clock to 12 o’clock range). Note that the Opto LED will only illuminate to indicate when gain reduction is being applied.

Blends between an ultra-clean DI channel (when turned fully counter-clockwise) and a unique distortion channel that adds transformer saturation and amp-like distortion as this control is turned clockwise.

Three-position switch rolls off low frequencies to compensate for additional low end content when applying distortion via the Color control. Note that this switch only affects signal that has been processed through the distortion channel of the Color control, the HPF does not affect the clean side of the HDI.

Adds emphasis to the high and high-mid frequencies. Fully counter-clockwise is flat, turn this control clockwise for an increasingly brighter sound.

HDI Recording Bass Guitar

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.

HDI Recording with Acoustic Guitar

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.

HDO Electric Guitar Preamp

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.

HDI as Synth DI

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.

Model: HDI
Manufacturer: Radial Engineer