Radial Engineering

StageBug SB-4 Ultra-Compact Active DI for Piezo Pickups

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  • StageBug SB-4 Ultra-Compact Active DI for Piezo Pickups
  • StageBug SB-4 Ultra-Compact Active DI for Piezo Pickups, input options
  • StageBug SB-4 Ultra-Compact Active DI for Piezo Pickups, input/output jack
Our Low Price: $99.99

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If you - like me - don't like dragging a lot of extra gear to the gig, this little guy might just be your new best friend. The new Radial StageBug SB4 is an Active Direct Box which is designed for use with Piezo Pickups. If you're not familiar, a direct box is the least complicated method for getting your instrument's sound to the main PA. Most well-prepared soundmen -- and women, can't be sexist here! -- carry a bucketful of "DI's." ("Direct Box" is a condensed version of "Direct Injection Box," hence the odd acronym.)

So why should you bring your own?

Here's why - the "general purpose" ones that your sound engineer has rarely "play nice" with the piezo-based pickup on your bass. And while the engineer might not care, you should. Unlike typical direct boxes - which aren't optimized for piezo pickups - the SB-4 features a high 5meg-ohm impedance that smoothes out the troublesome peaks (and thus, quacky sound) that give piezos a bad name. The higher impedance also broadens the frequency response for a more open, natural sound.

The SB-4 is basically a tiny version of the popular PZ-DI (with some scaled back features) and offers a super-easy interface with a sound board operator at your gig. Plug your bass in one end, and the engineer can plug in an XLR (mic) cable to the other... and you're in business!

The active electronic circuitry in the SB4 converts the impedance and balances the signal, allowing for long runs from stage to mixing board - no worries about signal loss or ugly noise. And, like all Radial gear, it's built like a tank.

Audio circuit type: Piezo optimized active bufferTo help eliminate feedback on stage, the SB-4 is equipped with a high-pass filter and 180° polarity reverse switch. The high pass filter dials back excessive bottom end (on a gradual curve) to limit woofy resonances that can cause the top of the instrument to vibrate (and create feedback). The 180° polarity reverse helps reduce acoustic hot spots on stage by changing the phase relationship between the PA system and room acoustics. Reversing the polarity like this can blank out feedback-inducing acoustic peaks, without having to resort to severe EQ adjustments that "ugly up" your sound.

Along with the standard XLR output to feed the PA, there's also a 1/4" output so you can also send your bass to an onstage amp, electronic tuner, or headphone amp. Operating power for the SB4 comes from the console's 48V phantom power (required), eliminating the need for batteries or external supply.

The compact size and killer features make the StageBug SB4 the perfect companion for concert venues, bluegrass stages and recital halls that call for lots of great sound (but not lots of gear).


  • Frequency response: 20Hz to 20kHz
  • Total harmonic distortion: <0.006%
  • Dynamic range: 100dB
  • Input impedance: 5Meg Ohms
  • Maximum input: +4dBu
  • Gain: +2dB
  • Output impedance: 330k Ohms
  • Equivalent input noise: -101dBu
  • Noise floor: -97dBu
  • Intermodulation distortion: <0.01%
  • Phase deviation: 10° @ 50Hz


  • Switches: High Pass Filter, Phase, Ground Lift
  • Low-cut filter: 150 Hz
  • Filter slope: 6dB/octave
  • Instrument input: ¼" buffered with piezo optimized load
  • Auxilary output: ¼" buffered to drive guitar effects, amplifier or tuner
  • Balanced output: Pin-1 ground, pin-2 (+), pin-3 (-)
  • Polarity reverse: 180°
  • Ground lift: Soft lift with 100 Ohms to ground
  • General Construction: 16 gauge steel chassis & outer shell
  • Finish: Baked enamel
  • Size: (L x W x D) 4.5" x 1,85" x 1.35" (114mm x 47mm x 34mm)
  • Weight: 0.55 lbs (250 grams)
  • Power: 48V phantom power
  • Warranty: Radial 3-year, transferable

Specifications are subject to change without notice.



This unit does not use batteries or a power adapter. For operation, its XLR output must be plugged into a mixer/PA channel that has phantom power active, with no adapters used. If you don't know what phantom power is, check out our FAQ on the subject, under Resources, above.

Still confused/unsure? Ask us - we're here to help!


WARNING: Cancer and/or Reproductive Harm
According to California state law, if you are a resident of California, we
must notify you that this product contains chemicals known to the state
of California to cause cancer, birth defects or other reproductive harm.
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Warranty Information

Standard Warranty:
All products sold by RADIAL come with a 1-year limited warranty. This limited warranty protects you against defects in workmanship. The warranty does not cover any consequential or inconsequential damage or any losses. Specifically, if you have a problem due to defect, you must make the arrangements and cover the costs to return the product to us with a copy of the original sales invoice and we will repair the product and return it to you at our cost. All warranty claims require a return authorization. Contact the RADIAL service department for details.

Transferable 3-Year Warranty:
Some RADIAL products come with a 3-Year Transferable Warranty. This means that if you buy the product and decide to sell it, the warranty can be transferred to the person that buys it, thus providing continuous warranty support and added value. This Transferable Warranty follows the same procedures and limitations outlined in the Standard Warranty. This means that if you sell the product, you must provide the buyer with a copy of your original invoice so that he, in turn, may be able to submit this should a warranty claim be required.

Warranty Limitation:
As with all typical warranties, only manufacturing defects are covered. Furthermore, parts that are subject to wear and tear such as switches, potentiometers and tubes are not covered under this warranty. This, however, does not mean that these will not be repaired or replaced free of charge. We pride ourselves in supporting the products we sell and will often exchange these parts free of charge pending the age of the device. This decision will be undertaken by RADIAL and in no way obliges the company to perform such tasks.
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