Radial Engineering

Radial Engineering StageBug SB-5 Passive Laptop DI Box

4.7 (34 reviews)

Compact passive DI box that cleanly converts stereo laptop audio to balanced mono for professional PA systems without any power needed.

$124.99*
In Stock on Amazon.com
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*Price sourced from Amazon.com. Last updated:Jun 04, 2026.Price and availability are subject to change.

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Overview

The Radial Engineering StageBug SB-5 is a purpose-built passive direct box designed to bridge the gap between consumer audio devices and professional PA systems. It accepts a stereo unbalanced signal from a laptop, tablet, smartphone, or other device via its built-in 5-foot 1/8-inch TRS cable and converts it to either a balanced mono XLR output or dual 1/4-inch TRS stereo outputs. The internal isolation transformer handles the signal conversion while simultaneously breaking ground connections, which is the primary cause of hum and buzz when plugging consumer electronics into professional audio equipment.

Because it is entirely passive, the SB-5 requires no batteries or phantom power, making it one less thing to troubleshoot during setup. A -15dB pad is available for taming hot output levels from devices with high headphone output. The enclosure follows Radial's signature rugged construction in a compact form factor that fits easily on a lectern, behind a display, or tucked beside a laptop on a table. For presenters, worship teams, DJs running backing tracks, and AV technicians who regularly interface consumer devices with installed sound systems, the SB-5 provides a straightforward, dependable connection path.

Key Features

Stereo Direct Box Optimized for Consumer Device Audio

Specifications

Type
Passive Stereo Direct Box
Input
1/8" (3.5 mm) Stereo TRS, 5-foot integrated cable
Outputs
2 x 1/4" TRS (Stereo), 1 x XLR (Mono)
Pad
-15 dB
Isolation
Transformer-based
Power
None required (passive)
Brand
Radial Engineering
Model
StageBug SB-5

Pros & Cons

👍 Pros

  • Fully passive operation means no batteries or power source to worry about
  • Transformer isolation effectively eliminates ground loop hum and buzz
  • Built-in 5-foot 1/8-inch cable connects directly to laptops and mobile devices without adapters
  • Compact, rugged enclosure is easy to fit on a podium or stage without taking up space
  • Flexible output options with both stereo 1/4-inch TRS and mono XLR

👎 Cons

  • Sums stereo to mono on the XLR output, which loses stereo imaging for music playback
  • Fixed 5-foot input cable cannot be replaced or extended without an additional adapter
  • No ground lift switch, relying solely on transformer isolation for noise rejection
  • 15dB pad is the only attenuation option with no variable control

Frequently Asked Questions

No. It is a fully passive design using transformer isolation, so it requires no batteries, phantom power, or any external power source to operate.
The internal isolation transformer breaks the electrical ground connection between the laptop and the PA system, effectively eliminating hum and buzz caused by ground loops.
It includes a built-in 5-foot cable with a 1/8-inch (3.5 mm) stereo TRS connector that plugs directly into standard headphone outputs on laptops, tablets, and smartphones.
It offers two 1/4-inch TRS output jacks for stereo use or a single XLR output for summed mono. For true stereo to a mixer, you would use both 1/4-inch outputs.
The pad reduces the input signal level by 15 dB, which is useful when the source device outputs a hot signal that could overdrive the mixer input.