RDL ST-UMX3 Three-Channel Miniature Audio Mixer

Compact Audio Mixer for Mic and Line Sources

The RDL ST-UMX3 Universal Audio Mixer is a compact, installation-friendly mixer designed to combine multiple microphone or line-level sources into a single output. It allows you to cleanly mix up to three inputs while maintaining control, clarity, and consistent output levels, making it a practical solution for commercial audio systems and small sound reinforcement setups.

Flexible Input and Output Configuration

Each of the three inputs on the ST-UMX3 can be individually set for microphone or line-level operation, giving installers and system designers flexibility when integrating different audio sources. The output is also switch-selectable for mic or line level, allowing seamless connection to amplifiers, mixers, or powered speakers without additional adapters.

Designed for Commercial and Installed Audio Systems

This mixer is well suited for offices, classrooms, retail environments, medical facilities, and other fixed installations where multiple audio sources need to be combined reliably. Paging microphones, background music players, wireless mic receivers, and line-level devices can all be summed into a single, controlled signal path.

Miniature Stick-On Form Factor for Easy Mounting

The ST-UMX3 is part of RDL’s Stick-On series, featuring a compact enclosure that can be mounted discreetly under desks, behind racks, inside cabinets, or on walls. Its small footprint simplifies installation in tight spaces while keeping audio infrastructure clean and unobtrusive.

Clear Level Control and Visual Monitoring

Each input channel includes an audio-taper gain control for precise level adjustment, allowing balanced mixing of multiple sources. Dual LED output meters provide visual feedback of signal activity, helping installers quickly verify proper signal levels during setup and maintenance.

Balanced and Unbalanced Signal Compatibility

All inputs and the output support both balanced and unbalanced audio connections. This ensures compatibility with a wide range of professional and consumer audio equipment, reducing the need for additional signal-conditioning hardware in mixed-format systems.