Shopping Cart

Radial Engineering Pro DI Passive


Raidal ProDI Passive Mono Direct Box at a Glance:

  • Full-range passive direct box
  • Custom isolation transformer eliminates noise
  • Really easy to use
  • Built like a tank

Passive vs. Active DI
The Radial ProDI and ProD2 (stereo version) are full-range passive direct boxes. Active direct boxes employ electronic circuits to change the impedance from hi-Z to lo-Z and balance the signal. Passive DIs instead employ a simple passive transformer to do the work. Active DIs require batteries, 48V phantom-power or external power supplies to power their circuits, while passive transformer-equipped direct boxes do not require any power to perform their task. The advantage of a transformer over typical active circuits can be summarized as “a great device to reduce system noise” in a sound system. To accomplish the task of noise elimination, the Radial ProDI and ProD2 features first-class transformers and require no batteries or power supply.

Custom Isolation Transformer
The Radial ProDI is equipped with a custom-made audio transformer, which provides exceptional signal handling without saturation. More importantly, the ProDI’s custom transformer has extremely low phase distortion in the critical bass and mid regions. The ProDI’s transformer provides 100% isolation, to eliminate hum- and noise causing ground loops, while maintaining signal integrity. Inside the ProDI you’ll also find isolated XLR connectors, to eliminate chassis ground potential, as well as a military-spec PC board, with a full surface ground plane to reduce susceptibility to RF noise. The result is exceptional clarity and definition, at an attractive price point.

Really Easy to Use
The best feature of the ProDI is “plug and play” ease of use. All you do is connect the instrument to the 1/4″ inputs, the 1/4″ through the jack to the stage amplifier(s) or mixer and the XLR output to the mixing console and you are done. Any distortion? Hit the -15dB pad. Any noise? Just depress the ground lift switch. You will find that with acoustic guitars and basses, the natural tone of the instrument will shine through with a smooth and musical rendering. For electrically powered devices, such as keyboards, the ProDI will immediately eliminate troublesome ground loops while delivering solid dynamics, with a full rich sound.

Solid Construction
Look inside a ProDI and you’ll find the build quality and components to be of only the highest professional standards. Radial’s proven construction methods and materials ensure years of trouble-free service — able to withstand the rigors of the most demanding, high-use professional environments. Radial pioneered the use of its innovative “book cover” design, which provides a protective zone around the switches and connectors that keep the components safe. The 14-gauge welded I-beam inner chassis and 14-gauge outer shell found in the ProD2 and ProDI greatly reduce the possibility of torque stresses being applied to the PC board. Stress on circuit boards causes broken and intermittent solder joints, a common cause of failure in commercial rental and other high-use environments. A full bottom no-slip rubber pad works double-duty by providing protection from electrical shock and making sure these DI’s stay put.

Radial ProDI Passive Mono Direct Box Features:

  • Full-range, passive direct box
  • Isolation transformer eliminates noise
  • Very low harmonic and phase distortion
  • Compact and rugged design
  • Ideal for live sound and studio.
  • Isolated XLR connector eliminates chassis ground potential
  • Custom audio transformer on input provides 100% isolation to eliminate hum- and noise-causing ground loops, while maintaining signal integrity.
  • Military-spec PC board, with full surface ground plane to reduce susceptibility to RF noise
  • High-grade switches — long life, high cycle for reliable performance
  • 14-gauge steel welded I-beam construction makes it virtually impossible to torque the PC board
  • -15dB pad reduces the level going in from loud sources that could overload the circuit and cause distortion
  • Book-end design creates a protective zone around the switches & connectors, indestructible 14-gauge steel construction
  • Full no-slip rubber bottom pad provides mechanical isolation, electrical insulation and prevents the unit from sliding around
  • Balanced male XLR output connector, AES standard with pin-1 ground and pin-2 hot
  • Lift switch lifts the ground to pin-1 on both channels.
  • Heavy-duty baked enamel finish for excellent durability


Radial Engineering Pro DI Passive is a high-quality passive DI box designed for converting high-impedance instrument signals into balanced low-impedance signals. This professional audio equipment is ideal for live performances, studio recordings, and music productions.

Eliminating hum and buzz, this direct input box features an audio transformer that delivers exceptional audio quality. The ground lift switch ensures a clean signal by removing any ground loops. The Radial Engineering Pro DI Passive is an essential tool for sound engineering professionals.

Whether you’re recording an acoustic guitar, a bass guitar, or a keyboard, this DI box is capable of handling any instrument signal. It also works well with line-level signals, making it versatile for any audio setup. The 1/4 inch input and XLR output make it easy to connect to any audio interface or mixer.

The Radial Engineering Pro DI Passive is portable and durable, making it an ideal tool for musicians and sound engineers on the go. Its compact design allows for easy transport and storage, while its rugged construction ensures that it can withstand the rigors of live performances and studio sessions.

In summary, the Radial Engineering Pro DI Passive is a must-have for any musician or sound engineer who wants to achieve exceptional audio quality. Its ability to eliminate hum and buzz, its audio transformer, and ground lift switch make it an essential tool for any audio setup. With its portable and durable design, this passive DI box is sure to provide years of reliable use.




Reviews (0)


There are no reviews yet.

Be the first to review “Radial Engineering Pro DI Passive”

Your email address will not be published. Required fields are marked *

You have to be logged in to be able to add photos to your review.

Shopping cart
Sign in

No account yet?

Create an Account

Radial Engineering Pro DI Passive