251 Paging/Passenger Speaker Amplifier

The 251 is a remote-mounted, two-channel Passenger Speaker Amplifier. The primary function of the component is passenger PA briefing. Each speaker channel can provide 40 W into a 1 Ω load or 30 W into 2 Ω. Each speaker output is internally protected against open and short circuits, as well as over-temperature conditions.

The unit features a remote electronic speaker mute control, which can be used to reduce the volume upon landing when connected to the aircraft’s Weight-On-Wheels switch (when lower cabin ambient noise levels are present). The speaker mute control drops the speaker level by -6 dB when grounded.

The design incorporates a musical chime tone to alert passengers of a change to the Fasten Seat Belt or No Smoking sign status. The unit also features a Cabin Call ringer tone for the Cockpit to Cabin intercom system.

Left and right monitor outputs are provided for connecting to a cabin headphone amplifier or headphone audio distribution system. The monitor outputs carry the same audio signals as the speaker outputs. Stereo audio inputs are provided for cabin background music when desired.