Radial Firefly

High Output Vacuum Tube DI Box


About this item



The Radial Firefly is a studio-quality direct box that combines the clarity and detail of an active DI with a tube drive circuit that provides vintage warmth and pleasing harmonics to any instrument.

  • 12AX7 tube drive and class-A front end
  • Dual inputs with separate gain & remote switching
  • Drag control load correction for optimal tone
  • Variable output connects directly to a PA

Fatten up your DI tracks

The Firefly’s drive circuit utilizes a 12AX7 vacuum tube, which is the most popular tube made today and can be found in nearly all guitar amplifier designs. This helps provide the character and feel of a vintage device, while still maintaining low distortion and noise profiles common to modern pro audio equipment. The Firefly excels when used on instruments that sound too clinical or one dimensional when recorded directly, adding punch and warmth to bass or guitar tracks both on stage and in the recording studio.

When viewing specifications, one has to differentiate between products that are designed to provide accuracy versus those designed to color and enthrall. The Firefly falls into the second category. Therefore the specifications that are normally used to qualify ‘accuracy’ have been omitted leaving those that are still relevant such as noise. One must also consider that tubes are inherently noisy compared with solid-state devices, so even here, the specs may seem less than ideal. But tubes bring a sonic character that excites. With the Firefly… one must really listen to appreciate.

Audio circuit type:100% discrete class-A FET with tube drive
Number of channels:1 with A/B input select
Frequency response:20Hz ~ 20kHz
Dynamic range:>100dB
Gain:20dB (Maximum)
Total harmonic distortion:0.15% from 20Hz ~ 20kHz
Intermodulation Distortion:0.3%
Input Impedance:Drag Off: 3.9 Meg-Ohm | Drag On: Variable 22k ~ 500k
Output Impedance:150Ω
Equivalent Input Noise:-101dB
Noise:-98dB at unity gain
Maximum Input:Variable from -12dB ~ +20dB
180° polarity reverse, Ground lift, HPF, Drag Control, Level Control, Phase Adjustment, Effects Loop, Remote Footswitch, Boost
Input Connectors:1/4″ Hi-Z, 1/4″ TRS Insert
Output Connectors:XLR, 1/4″
Construction:14-gauge steel
Size (L x W x D):5.75″ x 8.25″ x 1.75″ (2.75″ with handle) 146mm x 210mm x 45mm (70mm with handle)
Weight:3.95lbs. (1.80kg)
Power:5-pin XLR, +/-16V & 48V, 1600mA
Conditions:For use in dry locations only between 5°C and 40°C
Warranty:Radial 3-year, transferable


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