The MA501t is a low-voltage mono power amplifier engineered for use in distributed sound applications. Designed for use with SoundTube and other high-fidelity speakers, the MA501t provides 50 watts of output power at 25V, 70V or 100V. A 12V trigger is provided for auto-on/off functions. Recessed gain control is available via the front panel; this deters unauthorized tampering with levels or other settings. Designed for distributed sound applications, the MA3501t amplifier incorporates large toroidal power and audio output transformers for high power handling, and offers transformer taps at 25, 70 and 100V plus bypass mode. It delivers 350 watts into 4ohms, 25V, 70V and 100V; and 225W into 8ohms, with a frequency response of 30 Hz - 35 kHz +/- 0.5 dB. Inputs are RCA (unbalanced) and Euroblock (balanced) connectors, with outputs to speakers via Euroblock connectors. A selectable limiter is provided, along with a 3 position subsonic filter (40Hz, 60Hz or off); auto music sensing and a 12V trigger option are provided for remote activation / deactivation. The unit occupies two rack units; it is fan-cooled and offers overload, short circuit and heat protection along with peak output protection. All controls for the MA3501t are presented on the rear panel to deter tampering with levels or settings. The MA3501t is for use with SoundTube and Rockustics products. When in use in conjunction with outdoor speakers, the amp should be placed inside or in a weatherproof concealment.