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Audio circuit type:      Passive, transformer based
Number of channels:     Single channel (mono)
Frequency response:      20Hz ~ 18.5KHz (± 0.2dB)  
Dynamic range:      128dB
Maximum input:      +18dB @ 20Hz
Total harmonic distortion:      0.01% from 20Hz~20kHz @-10dB
Phase deviation:      1° @ 100Hz; 8° @ 20Hz
Input impedance:      140k Ohms, unbalanced
Output impedance:      150 Ohms, balanced       
Transformer:     Radial RT-DBI, 12:1 ratio
Shield:     Faraday, mu-metal can
Input pad:      -15dB  
Ground lift:      Disconnects pin-1 at XLR output
XLR configuration:      AES standard (pin-2 hot)
Connectors:     1/4" in & thru, XLR-M out
Construction:      14 gauge steel chassis & outer shell
Finish:     Baked enamel
Size:  (W x H x D)     70 x 108 x 44mm (2.75” x 4.25” x 1.75")
Weight:      .54kg (1.2lbs)
Shipping Size: W x H x D:     102 x 76 x 165mm (4.00" x  3.00"  x 6.50")
Shipping Weight:     0.61 kg (1.35 lbs)
Power:      Passive, no power required
Warranty:      Radial 3-year, transferable

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Radial Engineering ProDI Passive Direct Box

R800 1100
1.40 LBS
Usually ships within 24 hours
Calculated at checkout

Product Description

The Radial ProDI is a passive direct box that combines exceptional audio performance with solid dependable construction, making it the ideal general duty direct box for stage and studio.

The heart of the ProDI is a custom wound Radial transformer. It features an exceptionally high 140kΩ input impedance to reduce loading while enabling the ProDI to handle extreme signal levels at all frequencies without distortion. This is further improved upon with an internal mu-metal shield to protect against electromagnetic fields that can cause unshielded transformers to distort.

This compact direct box begins with 14-gauge steel I-beam skeleton for added rigidity and Radial's unique book-end design that creates a protective zone around switches and connectors. Glass filled nylon connectors and high cycle switches combine with the mil-spec PCB and internal RF filtering to provide durability and noise-free performance. A full bottom no-slip pad provides both mechanical isolation and electrical insulation to further protect against the rigors of professional touring.

The ProDI is ideally suited for instruments such as bass guitar, active acoustics, keyboards and just about anything else! When you consider all of the features and the affordable price tag, it is no wonder the Radial ProDI has become one of the most popular direct boxes ever made.

The Radial ProDI… Spectacular performance at a price that anyone can afford!


  • Compact passive direct box for stage and studio
  • Able to handle huge transients without distortion
  • Transformer isolation eliminates noisy ground loops
  • Plug and play easy to use feature set - on stage or in the studio