RDL ST-MA2 – 2 W Mono Monitor Amplifier with Muting

What is the RDL ST-MA2?

The RDL ST-MA2 is a compact 2 W mono audio monitor amplifier with control inputs that mute or reduce its output. It typically drives a small tabletop or overhead monitor speaker in conference rooms, boardrooms, courtrooms and public forum panels.

How does it work?

The line-level input may be wired balanced or unbalanced, and the output drives standard speakers from 4 to 45 Ω. Normal gain is preset with a trimmer, and two independent control inputs, activated by connecting to ground, select 3 dB or 6 dB of attenuation or full muting. Switching takes less than 50 µs, and muted attenuation exceeds 90 dB at 1 kHz, which suits automatic mixing systems built from other RDL modules. The module runs from a ground-referenced 24 Vdc supply at 200 mA for rated output. RDL lists STICK-ON mounting accessories such as the SR-4 and STR-19A for this module.

What are the key features?

• 2 W monitor output — The amplifier delivers 1.75 W RMS continuous and 2 W RMS maximum into 8 Ω and drives 4 Ω loads.
• Fast, silent muting — Control inputs mute the output in under 50 µs with more than 90 dB of attenuation at 1 kHz.
• Selectable attenuation steps — Two independent inputs select 3 dB or 6 dB of attenuation for conferencing and automatic mixing systems.
• Balanced or unbalanced input — The 20 kΩ bridging input accepts balanced or unbalanced line-level sources.
• Adjustable gain — A trimmer on the module presets normal gain for the monitor speaker.