The AA400PHD is a six input channel mixer amplifier designed for distributed business paging and background music (BGM) systems, medium to large speech privacy systems, and in applications where music on hold (MOH) plus paging is required.

With one microphone/line input and two stereo line inputs, the AA400PHD will accommodate a variety of input sources including paging microphones, media players, and digital music receivers. The AA400PHD includes a patent pending automatic system test, the Push Here Diagnostic (PHD). The PHD button is designed to check the connected speaker lines for wiring and impedance errors. This test can be activated once all speakers are connected and the circuit automatically verifies that the attached speakers' tap settings do not exceed the amplifier's rated power, no speakers are mistakenly tapped at 8 ohm, and the speaker wire is free from shorts. The unit also incorporates a Remote Input Selection and Remote Level Control feature that allows the integrator to use a remote wall plate (Atlas Sound model WPD-RISRL) and allow the user to select the input and adjust the volume from that wall plate up to 200 feet from the amplifier.

The AA400PHD provides 400-watts output power into 25V, 70.7V, or 4 ohm speaker systems. Rear panel DIP switch allows for creation of Zone 2 output mix using any or all of inputs 1-4. Unit can also be set-up to mute Inputs 2 through 6 on signal from Input 1 for paging applications where other input sources need to be muted during a page. Inputs 1-4 are either Mic or Line input selectable and Phantom Power is an option when using them as a microphone input.