BSS AR-133 – Active Direct Injection Box

Product Overview

The BSS AR-133 is a professional active direct injection box designed to convert high-impedance unbalanced instrument and line-level signals to low-impedance balanced XLR outputs for connection to mixing consoles and audio processors. Built around an enhanced audio path derived from the renowned AR-116, the AR-133 delivers exceptional signal integrity for live sound, studio recording, and installed AV applications. Its dual power supply — phantom power with automatic 9V battery backup — makes it a dependable choice for touring and fixed-installation environments alike.

Product Description

The BSS AR-133 active DI box provides a transformer-balanced, isolated output feed from instrument, line, or amplifier-level sources. Two parallel 1/4" jack inputs and a parallel XLR input accept a wide range of signal sources, while the transformer-balanced XLR output delivers clean, noise-free signal to the console or signal processor. A switchable input attenuation pad offers 0, -20, or -40 dB of gain reduction, accommodating sources ranging from passive instruments to speaker-level outputs from power amplifiers. The ground-lift switch on the output disconnects Pin 1 from unit ground, providing a quick and effective remedy for ground-loop hum in problematic signal chains.

Power is sourced from phantom power (20–48V DC) drawn from the mixing console or preamplifier. If phantom power is interrupted or accidentally disabled, the AR-133 automatically switches to an internal 9V PP3 alkaline battery without any interruption to the audio signal. An LED indicator continuously illuminates when running on phantom power and flashes approximately every two seconds when operating on battery, giving the operator clear status at a glance. The rugged aluminium extrusion housing with polyurethane end-cheeks protects internal circuitry in demanding environments, and the arched case profile allows cables to route neatly underneath the unit.

The AR-133 active balancing capability extends its usefulness beyond traditional DI applications: it can convert unbalanced line-level signals — from keyboards, DJ controllers, media players, and electronic sources — to balanced outputs throughout a signal chain, making it a practical problem-solving tool for AV integrators and system engineers. Sound quality is particularly notable on acoustic and bass guitar sources, where the high input impedance and low distortion preserve transient detail and tonal character.

Key Features

• Automatic Dual Power Supply — Switches seamlessly from phantom power (20–48V DC) to internal 9V PP3 battery if phantom is lost, ensuring uninterrupted operation.
• Transformer-Balanced Output — Provides galvanic isolation between input and output for maximum noise rejection and signal integrity.
• Three-Position Input Pad — Selectable attenuation of 0, -20, or -40 dB accommodates instrument, line, and power-amplifier output levels.
• Ground-Lift Switch — Disconnects output Pin 1 from chassis ground to eliminate ground-loop hum quickly and effectively.
• Multiple Input Connectors — Two parallel 1/4" TRS jacks plus a parallel XLR input accept guitars, keyboards, line sources, and unbalanced signals.
• Active Balancing — Converts unbalanced signals to balanced XLR throughout, functioning as a line balancer in addition to a DI box.
• Rugged Aluminium Housing — Extrusion-formed aluminium case with polyurethane end-cheeks withstands the rigours of touring and installed use.
• Power Status LED — Solid illumination confirms phantom power; flashing indicates battery operation for immediate status awareness.
• Ultra-Low Distortion — THD below 0.005% at 1 kHz (0 dBu output) maintains source fidelity across all signal types.
• High Signal Headroom — Accepts up to +49 dBu at -40 dB pad, handling the full range of professional and semi-professional sources.

Technical Specifications