RDL STMA2 Two Watt Mono Audio Amplifier with Muting

Herman # RDLSTMA2




The ST‑MA2 is a compact audio monitor amplifier with control inputs to mute or reduce the gain of its output. This module may be used in conjunction with other RDL® modules to configure automatic mixing systems or may be used alone as a single‑speaker monitor amplifier. The ST‑MA2 is typically used to drive a small tabletop or overhead monitor speaker in a conference room, boardroom, courtroom, public forum panel or similar installation. The ST‑MA2 is ideally suited for use in automatic mixing systems due to its control inputs.

The line‑level input may be wired balanced or unbalanced. The audio output will drive standard speakers from 4 to 45 Ω. Normal gain is preset by means of a trimmer on the module.

For tabletop installations, use the ST‑MA2 with the WDG1 and RU‑SP1.
  • Single‑Speaker Monitor Amplifier
  • Conferencing Monitor Amp
  • Monitor Amp with Muting and Externally Actuated Attenuation Steps
  • Fast, Silent Audio Switching
  • Multiple Control Inputs
  • Adjustable Gain

Input Impedance:

20 kΩ Balanced or Unbalanced Bridging

Input Level:

‑10 dBV minimum for 2 Watts RMS output

Output Impedance:

8 Ω (will drive 4 Ω loads)

Output Power:

1.75 Watts RMS Continuous; 2 Watts RMS max.


< 0.5%


45 Hz to 14 kHz


> 60 dB (50 Hz to 120 Hz)

Residual Noise:

< ‑80 dB (below 2 Watts RMS)

Switching Time:

< 50 us

Attenuation (Muted):

> 90 dB (1 kHz),
> 85 dB (300 Hz to 3 kHz)
> 75 dB (20 Hz to 20 kHz)

Selectable Attenuation:

3 dB or 6 dB, each setting individually selectable using two independent inputs (connect to ground to activate)

Power Requirement:

GROUND‑REFERENCED, 24 to 33 Vdc @ 200 mA for rated output (220 mA @ 2 Watts RMS)

Ambient Operating Environment:

0° C to 50° C

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