Radial Engineering StageBug SB-4 Compact Active Piezo DI Box for Acoustic Guitar, Violin & Upright Bass

Product Introduction

The Radial Engineering StageBug SB-4 is a professional active direct box specifically engineered for acoustic instruments equipped with piezo pickups. Designed with an ultra-high 5 Meg Ohm input impedance, the SB-4 preserves the natural character of your instrument while eliminating the harsh peaks, squawk, and thin tone commonly associated with piezo transducers.

Compact enough to fit inside an instrument case yet powerful enough for professional touring, the StageBug SB-4 delivers studio-quality sound for acoustic guitars, violins, cellos, mandolins, ukuleles, and upright basses. Powered directly from standard 48V phantom power, it requires no batteries, making it a reliable solution for live performances, worship venues, recording studios, and professional AV installations.

Product Description

Unlike conventional DI boxes, the StageBug SB-4 is optimized specifically for piezo-equipped instruments. Its high 5MΩ input impedance allows piezo pickups to operate correctly, resulting in smoother frequency response, improved low-end performance, and a more natural acoustic sound.

The active buffer circuit balances the signal and enables cable runs up to 100 meters without signal degradation, making it ideal for large stages, auditoriums, churches, and event venues.

Additional professional features include a Ground Lift switch to eliminate hum and ground loop noise, a 180° polarity reverse switch for phase correction, and a High-Pass Filter (HPF) to reduce unwanted low-frequency rumble. An auxiliary output allows simultaneous connection to a stage amplifier while sending a balanced XLR signal to the front-of-house mixer.

Built with a rugged 16-gauge steel chassis, the StageBug SB-4 is designed to withstand demanding professional use while delivering exceptional audio clarity and reliability.

Key Features & Benefits

Active DI box optimized specifically for piezo pickups

Ultra-high 5 Meg Ohm input impedance preserves natural instrument tone

Eliminates harsh "piezo squawk" and sharp frequency peaks

Provides smoother and more natural acoustic sound

Powered by standard 48V phantom power

No batteries required for operation

Balanced XLR output for professional PA and recording systems

Auxiliary output for connecting stage amplifiers

Supports cable runs up to 100 meters without signal loss

Ground Lift switch reduces hum and ground loop noise

180° polarity reverse switch for phase correction

High-Pass Filter (HPF) reduces unwanted low-frequency rumble

Compact design fits easily inside instrument cases

Durable 16-gauge steel construction for touring and professional applications

Common Problems & Solutions

Problem: Piezo Pickup Sounds Thin and Harsh

Many piezo-equipped instruments produce an unnatural, brittle sound when connected directly to a mixer.

Solution:

The SB-4's ultra-high 5MΩ input impedance optimizes the interaction with piezo pickups, delivering a warmer, fuller, and more natural acoustic tone.

Problem: Excessive Piezo Squawk and Sharp High Frequencies

Piezo transducers often create unpleasant peaks that make instruments sound harsh and difficult to mix.

Solution:

The SB-4 smooths out problematic frequency peaks and reduces piezo squawk, resulting in a more balanced and musical sound.

Problem: Signal Loss Over Long Cable Runs

Long cable runs can cause signal degradation and noise issues during live performances.

Solution:

The active balanced output allows cable runs up to 100 meters while maintaining excellent audio quality and low distortion.

Problem: Hum and Ground Loop Noise

Acoustic instruments connected to large PA systems often experience unwanted hum and buzz.

Solution:

The Ground Lift function helps eliminate ground loop noise for cleaner and quieter operation.

Problem: Need to Feed Both PA System and Stage Amplifier

Performers often require a personal stage amplifier while simultaneously sending signal to the FOH mixer.

Solution:

The SB-4 includes an auxiliary output for stage amplifiers and a balanced XLR output for the PA system.

Ideal Applications

• Acoustic Guitar Performances

• Violin and String Instrument Amplification

• Cello and Upright Bass Systems

• Churches and Worship Venues

• Live Sound Reinforcement

• School and University Auditoriums

• Recording Studios

• Hotels and Ballroom Events

• Corporate Presentations

• Broadcast and Streaming Applications

• Rental and Event Production Companies

Technical Specifications

• Audio Circuit: Piezo Optimized Active Buffer

• Frequency Response: 20Hz – 20kHz

• Dynamic Range: 100dB

• Gain: +2dB

• THD: <0.006%

• Input Impedance: 5MΩ

• Output Impedance: 330Ω

• Maximum Input Level: +4dBu

• Input Connector: 1/4"

• Output Connector: Balanced XLR

• Features: Ground Lift, HPF, 180° Polarity Reverse

• Power Requirement: 48V Phantom Power

• Construction: 16-Gauge Steel Chassis

• Weight: 250g