Radial SB-4 StageBug Active Piezo DI Box


Radial SB-4 StageBug Active Piezo DI Box

RRP $189.00
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The Radial StageBug SB-4 is the perfect companion for orchestral artists, blue grass players and pop string quartets that need to turn it up when in concert. This compact active direct box has been engineered for piezo pickups without compromising tone.


Radial StageBug SB-4 - Active DI for Acoustic Instruments

The StageBug SB-4 is the perfect companion for orchestral artists, blue grass players and pop string quartets that need to turn it up when in concert. This compact active direct box has been engineered for use with piezo pickups without compromising the tone or frequency response. As such, this DI is perfect for connecting instruments that are best amplified with a piezo transducer to a PA system for sound reinforcement, such as violin, dobro, mandolin, cello, double bass, and other stringed instruments.

The key to the design is the very high 5meg-ophm input impedance. In contrast with typical direct boxes that use a 1meg-ohm input, the high impedance of the SB-4 smooths out troublesome peaks that are common in piezo pick ups, while fattening out the frequency response for a fuller, more natural tone. The active circuitry balances and converts the signal from high to low impedance to allow for long sends upwards of 100m without loss, providing impressive linearity and minimal distortion across the audio range.

A high pass filter and a 180° phase inversion switch help to tackle on-stage feedback issues common to acoustic instruments. By damping the bottom end frequncies, the high-pass filter removes many of the resonant frequencies of wooden instruments, reducing feedback risk. If issues still arise, the 180° phase flip can negate acoustic hot-spots on stage caused by standing waves. As a result of the phase relationships between the natural acoustics of a room and the PA system, these standing waves can create large peaks of a specific frequency at a particular location in the room, which can readily induce feedback. By reversing the phase polarity of the signal, the acoustic peak is phase cancelled, removing the hotspot entirely without using extreme equalization that could compromise tonal quality.

Connections include a 1/4" input, a 1/4" AUX out for a stage amplifier, plus a standard XLR output to feed the PA. The unit requires 48V phantom power from an external supply such as a mixing desk, removing the need for batteries.


  • Active DI optimized for piezo transducers
  • Smoothes out peaks, eliminates squawk
  • High pass filter eliminates resonance
  • 180° Phase polarity reversal to eliminate standing waves
  • Ultra compact to fit in your instrument case


Using the SB-4 on classical guitar

Connect your piezo pickup directly to the StageBug SB-4 to get the best tone. No preamp is required! Activate the low-pass filter to eliminate resonance and you are set to go. The SB-4 balances the signal for long runs and smoothes out the peaks for a more natural sounding concert guitar!

Using the SB-4 on dobro

Use the SB-4 with a piezo on your resonator guitar to capture the unique sound of the body. Connect the AUX out to a stage amp if you like and then send the signal to the PA. The SB-4 will help eliminate the mid range squawk and frequency peaks that often force the sound engineer to turn you down in the mix.  

Using the SB-4 on upright bass

Traveling with an upright is expensive! So reducing the size of the ancillary equipment is important. The super compact SB-4 connects from the piezo pickup to the PA and you do not need a preamp in between. The SB-4 delivers a deeper bass and more natural top end, greatly improving your tone through the PA.

View PDF brochure for Radial SB-4 StageBug Active Piezo DI Box

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