Brands Guides About
Radial Engineering R800-1120 ProD8 Rackmount DI 8-Channel — main product image
Radial Engineering

Radial Engineering R800-1120 ProD8 Rackmount DI 8-Channel

★★★★★5.0 (1 reviews)

Eight channels of transformer-isolated direct injection in a single rack unit — the Radial ProD8 is the professional standard for clean, ground-hum-free keyboard feeds at any scale.

$1,029.99*
✓ In Stock on Amazon.com
View on Amazon

*Price sourced from Amazon.com. Last updated:Jun 04, 2026.Price and availability are subject to change.

Affiliate Disclosure: Studio Supplies may earn a commission from qualifying purchases made through links on this page, at no additional cost to you. This helps support our editorial team.

Notice a mistake? Let Us Know

Overview

The Radial ProD8 is engineered for one task and executes it without compromise: take up to eight unbalanced keyboard, playback, or instrument-level signals and deliver them as balanced, transformer-isolated feeds to a console or interface, in a single rack unit, with redundant inputs on every channel. In live production — whether a Broadway pit, a touring keyboard rig, or a broadcast stage with multiple playback sources — the ProD8 solves the ground loop and cable-failure problems that erode signal integrity when you're running multiple instruments into a single system. What you hear at FOH is the keyboard itself: its harmonic structure, its dynamic range, its low-end weight — not a cable ground hum, not a power supply artifact, not a transformer-induced rolloff stealing the bottom two octaves.

The passive architecture is fundamental to the ProD8's sonic character. Without active circuitry, there is no power supply to introduce noise, no op-amp to color the midrange, and no voltage requirement that changes with rack temperature or power conditioning quality. Radial's custom transformers are wound for linear performance, which is engineering language for "they don't editorialize" — the transformers interface the impedances and provide galvanic isolation without imposing a sonic signature of their own. The reversible rack ears are a production-savvy detail: in a packed touring rack, having the choice of which panel faces front determines whether your crew can connect and troubleshoot quickly or needs to pull the unit. For keyboard-heavy productions where signal reliability is non-negotiable, the ProD8 is the professional specification.

Key Features

Passive 8-channel DI with Custom Transformers

Specifications

Channels
8
Type
Passive DI
Format
Rackmount (1U)
Transformers
Custom Radial transformers
Inputs
Redundant (main + backup per channel)
Design
High-dynamic-source rated
Rack Ears
Reversible (either panel can face front)
Power Required
None (passive)
Brand
Radial Engineering
Model
R800-1120

Pros & Cons

👍 Pros

  • Eight transformer-isolated DI channels in a single 1U rack space eliminates the need for eight separate single-channel DI boxes in keyboard-heavy productions
  • Custom Radial transformers provide linear frequency response — you hear the full tonal weight of the source instrument without transformer-induced coloration or low-end rolloff
  • Redundant inputs on each channel provide a wired backup path that maintains signal continuity if a cable fails during a live show, with no FOH intervention required
  • Passive design means zero power supply noise can enter the signal path — the noise floor of the ProD8 is determined entirely by the source, not the unit itself
  • Reversible rack ears allow the unit to be installed with either input or output panel facing front, adapting to any rack layout or cable management scheme

👎 Cons

  • Passive transformer design means the ProD8 provides no gain — if your keyboard output is weak, you need console preamp gain to recover level, which increases the preamp's contribution to noise
  • No ground lift switches are individually called out in the available specifications — confirm per-channel ground lift availability before assuming it in your signal chain
  • At 8 channels with no mixing capability, the ProD8 is a routing and isolation tool only — it does not replace a submixer or signal processor for complex keyboard rigs
  • The single-feature passive design commands a price that reflects Radial's transformer quality, which may be harder to justify for productions that don't require the full 8-channel density
  • The 1U rack format requires dedicated rack real estate — keyboard players building a portable pedalboard rig will need to plan accordingly

Frequently Asked Questions

The ProD8 is a passive DI — it requires no power of any kind to operate. Phantom power on the console or interface will not damage the unit, but it is neither used nor needed. This passivity is a signal chain asset: no power supply noise can be introduced into the audio path.
Radial's custom transformers are wound for linear response across the full audio bandwidth, which means low-frequency content from bass-register keyboard voicings and synthesizer subs passes through with the full weight of the source instrument. You hear the fundamental, not a transformer-induced rolloff that flattens the bottom end.
Each channel on the ProD8 accepts two inputs — a main source and a backup source — both wired simultaneously. If a cable fails or a keyboard player swaps instruments mid-show, the backup input maintains signal without any intervention from FOH. This is a genuine risk-elimination feature for live production, not a gimmick.
Yes — the rack ears reverse to allow either the input or output panel to face the front of the rack. This flexibility is significant in dense rack environments where access to inputs from the front is required, or where outputs need to face a specific direction for cable management.
The ProD8 works in both environments. In studio sessions it provides transformer-isolated DI signals from keyboards and playback sources directly to the console or interface, eliminating ground loops between keyboard rigs and the mix environment — a common source of 60Hz hum in dense studio setups.

Related Products