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Radial Engineering StageBug SB-1 Active Acoustic Direct Box

Radial Engineering
Radial Engineering StageBug SB-1 Active Acoustic Direct Box
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Expected availability: 7-14 business days

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Radial Engineering SB-1 Overview

  • 1Description
  • 2Highlights
  • 3Input
  • 4Input Pad
  • 5Output
  • 6Tuner Out
  • 7Phase Reverse
  • 8Connectors
  • 9Stand-Offs
  • 10Durable Switches
  • 11Circuit Board
  • 12Enclosure
  • 13Baked Enamel Finish

The Radial Engineering StageBug SB-1 Acoustic is an active direct box that has been specifically designed to provide a quick and dependable connection from your instrument to the PA. In other words, it converts the hi-Z output from your instrument--typically a 1/4" guitar jack--to a balanced low-Z signal via standard 3-pin XLR connectors. Balancing the signal reduces noise, enables longer cable runs, and improves the sound quality by properly matching the instrument's impedance with that of the PA. And with 48 volt phantom powering, the SB-1 does not require batteries or external supply to make it work. You simply plug in and you are set to go.

The active circuit features 220kΩ input impedance to eliminate problems with loading while delivering a smooth, warm sound to the audio system. This is particularly important when interfacing vintage guitars with low output pickups when you plan to do some recording or re-amping. This unit is also equipped with a -12 dB pad, which reduces input sensitivity of the circuit to enable louder instruments to be used without distortion. To reduce feedback, toggling the 180° polarity switch helps eliminate hot spots on stage that can cause low-frequency resonance.

Made to fit inside a guitar case for players that are on the move, this compact DI box delivers enhanced sound throughput. Although the SB-1 has been optimized for use with acoustic guitars, it is also well-equipped to handle electric bass guitars and keyboards.


Active direct box for acoustic guitar
Compact to fit in your guitar case
Plug-and-play and easy-to-use
48V phantom powered; no batteries needed


Unbalanced hi-Z input for your guitar or bass

Input Pad

Reduces the sensitivity by 12 dB for louder instruments such as an active bass guitar or keyboard so that they can be used without distortion


Sends the lo-Z balanced output signal to the PA system or audio workstation

Tuner Out

Always on, this thru connector is used to feed your tuner or your on-stage amplifier

Phase Reverse

180° polarity reverse helps tame hot spots on stage that can cause feedback


Glass-filled nylon connectors are insulated for reduced noise and feature nickel-silver contacts that will not tarnish


Made from steel and pressed into the outer casing to ensure proper retention of the circuit board

Durable Switches

With metal outer casing, the switches are rated at over 20,000 cycles for added durability

Circuit Board

Double-sided military grade with through-hole solder points for durability
Full surface ground plane to reduce susceptibility to noise


Made from 14 gauge steel to protect sensitive electronics inside while shielding against magnetic fields

Baked Enamel Finish

Keeps your StageBug looking new for years
UPC: 676101040643

Radial Engineering SB-1 Specs

Circuit TypeActive buffer with phase splitter
Frequency Response20 Hz to 20 kHz
Total Harmonic Distortion<0.006%
Dynamic Range>100 dB
Input Impedance800 k / 23 k
Maximum Input+2 dBu / +8 dBu
Gain+1.3 dBu / +4.4 dB
Clipping LevelOutput: +3.3 dBu / +12.3 dBu
Output Impedance330 Ω
Equivalent Input Noise-101 dBu
Noise Floor-97 dBu
Intermodulation Distortion<0.01%
Deviation from Linear Phase25 / 12° maximum
SwitchesPad, Phase
FunctionsAutomatic merge
Input Pad Switch-12 dB
XLR Configuration+ = Pin 2, - = Pin 3, Ground = Pin 1
Polarity ReverseYes, 180°
Construction16 gauge steel chassis and outer shell
FinishBaked enamel
Power48 V phantom power
Dimensions4.50 x 1.85 x 1.35" (11.40 x 4.70 x 3.40 cm)
Weight0.55 lb (0.25 kg)
Packaging Info
Package Weight0.65 lb
Box Dimensions (LxWxH)7.3 x 4.6 x 1.7"

Radial Engineering SB-1 Reviews

See any errors on this page? Let us know



Will this box boost the signal of my acoustic guitar going to the amplifier? I use a Dean Markley soundhole pickup which is passive and it's too quiet for my amp.
Asked by: Anonymous
This device is not an amplifier and will not boost output of a connected instrument.
Answered by: Mark S.
Date published: 2018-08-28
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