Description
The ST-MX3 is a compact 3-channel line-level mixer module designed to combine and control multiple line sources into a single line output. It provides three individually adjustable input gains and a line-level output capable of driving balanced or unbalanced loads. The module operates from ground-referenced or floating 24 Vdc and is part of RDL’s STICK-ON series for discreet placement.
Each input includes independent gain control allowing precise level matching between sources. The unit provides isolation between inputs to prevent cross-talk and accommodates signals of different level and impedance. Built for low-noise and low-distortion operation, it preserves audio integrity across a wide dynamic range.
Performance specifications include a 30 kO input impedance per channel, input gain range of -14 dB to +24 dB, and nominal output level of +4 dBu (adjustable). Measured THD+N is below 0.03% across 10 Hz to 20 kHz and frequency response is 10 Hz to 20 kHz within ± 0.5 dB. The mixer offers 18 dB of headroom and noise under -80 dB when inputs are set at 10 dB gain referenced to +4 dBu.
Connectivity is flexible: three bridging inputs accept balanced or unbalanced signals and the output is 400 O to drive low or high impedance balanced or unbalanced lines. The output’s unbalanced level is 6 dB below balanced line level, enabling easy integration into varied system topologies. Power uses RDL SupplyFlex compatible input allowing ground-referenced or floating 24 Vdc operation at 55 mA.
The ST-MX3 is ideal for adding additional line-level inputs to existing mixers or combining sources where level or impedance differs. Typical installations include small control rooms, paging interfaces, distributed audio nodes, and portable recording or playback setups. The small footprint and Stick-On form factor permit mounting in confined spaces or behind equipment panels.
Installation is straightforward with minimal configuration required and stable mechanical construction for long-term use. The compact package dimensions minimize rack or enclosure space requirements and the low current draw simplifies power distribution. The design emphasizes reliable audio performance and easy system integration for installers and audio technicians.