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6-input commercial mixer/amplifier — 400W x 1 at 70V

Item # 978A400PHD

California customers:
Please click here for your Proposition 65 warning.

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About the AtlasIED AA400PHD

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Background music and paging system

Atlas Sound's AA400PHD mixer provides power and distribution for background music and paging in a large business or institution. The AA400PHD delivers up to 400 watts RMS to a regular 8-ohm speaker load or to multiple transformer-coupled speakers in a 70-volt distributed system. Six inputs — four microphone/line and two stereo pairs — let you play multiple sources of music and make announcements from multiple locations.

Helps with its own installation

The AA400PHD features an automatic system tester, the Push Here Diagnostic (PHD) button. The PHD system checks the connected speaker lines for wiring and impedance errors, verifying that the attached speakers' tap settings do not exceed the amplifier's rated power, no speakers are mistakenly tapped at 8Ω, and the speaker wire is free from shorts.

Making announcements

You can set the mixer to mute inputs when Channel 1's microphone is on or when its button activates the remote trigger. You can also route any combination of inputs to a Zone 2 output for a second set of speakers or for music on hold (MOH) in a telephone system.

Also good in a church or school

The AA400PHD also works well in a multi-microphone PA system. Up to four microphone channels can handle singers and other musicians, while the line inputs can play recorded music or other programming. You can set the AA400PHD so that, whenever the main speaker (pastor, principal, teacher, or guest lecturer) speaks through his or her mic, the other channels mute.

Helpful connections, controls, and indicators

The microphone channels have phantom power available for condenser microphones. "Pre Out" and "Amp In" connections allow the AA400PHD to work in conjunction with another amplifier or external audio device.

The neatly laid-out front panel includes a control for each input channel and the master output so you can tweak the balance and volume of the entire mix. You can also control the master volume and channel mute functions remotely via a VCA control port and a Remote Mute connection. A Peak light indicates signal clipping, so you'll know to ease off the volume in order to maintain clean sound.

Atlas Sound AA400PHD

Atlas Sound AA400PHD rear panel

See what our satisfied customers have to say.

Product highlights:

  • amplified 6-channel mixer for commercial audio distribution
  • output: 400 watts RMS x 1 at 4 ohms, 25 volts, and 70.7 volts
  • Zone 2 output: 1.0 volt at 600 ohms (for MOH)
  • 6 inputs: four balanced microphone/line, two unbalanced stereo pair line (RCA)
  • dip switches for input routing, mute selection, and phantom power
  • remote and voice-activated mute
  • individual input and master output volume controls
  • bass control: +/-6 dB at 100 Hz
  • treble control: +/-6 dB at 10K Hz
  • "Pre Out" and "Amp In" loop, plus two preamp and tape outputs, for external processors, amplifiers, or recorders
  • dimensions: 16-1/2"W x 4-3/16"H x 14-1/4"D
  • weight: 41.6 lbs.
  • warranty: 3 years
  • Our 60-day money-back guarantee
  • MFR # AA400PHD

What's in the box:

  • 6-Input Mixer Amplifier with attached 6' AC power cord (3-prong plug)
  • Owner's Manual
  • AA & PA Series Accessories sheet

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More details on the AtlasIED AA400PHD

Russ B.

Product Research


Overview: The Atlas Sound AA400PHD is a six-input, 400-watt mixer-amplifier that is ideal for small to medium-sized retail, industrial, and commercial businesses that use background music, distributed paging, and music-on-hold. It can also be used for speech privacy systems. The amp can accommodate a variety of input sources, and can power a 4Ω speaker load, or 25V and 70.7V commercial speaker systems.

Push Here Diagnostic: This AAPHD series mixer amp includes a patent pending automatic system test to check the connected speaker lines for wiring and impedance errors. The front panel Push Here Diagnostic (PHD) button automatically verifies that the attached speakers' tap settings do not exceed the amplifier's rated power, that no speakers are mistakenly tapped at 8Ω, and the speaker wire is not shorted anywhere.

Inputs: The AA400PHD has six input channels with independent level controls on the front panel:

  • The Channel 1 input has a removable Phoenix (Euro Block) connector with +, -, and G terminals for balanced microphone or line level signals. DIP switches on the rear panel let you select mic or line input, and turn on Phantom power for condenser-type microphones. The 2-pin Remote Mute terminals let you connect the contact closure wires from a mic switch to activate the Mute circuit. A VOX Mute Sensitivity Control, located beside Input 1, can adjust the sensitivity of the mute circuitry. This can be used to mute background music on another input channel when a paging announcement is made on Input 1. A rotary Mic Trim pot lets you apply up to 20dB of gain to Input 1 when the input is set to Mic on the DIP switch.
  • The Channel 2 and Channel 3 inputs can accept more than one type of audio signal, but only one at a time. The inputs each have a 3-conductor Phoenix connector for a balanced mic or line source. Like Channel 1, you can select the type of input and turn on Phantom power for condenser mics through the DIP switches on the rear panel. Both inputs have rotary Mic Trim to fine tune the gain.
  • Channel 4 features a 3-conductor Phoenix connector for a balanced mic or line source, plus a 3.5mm stereo jack that is summed to mono. The type of input can be selected, and Phantom power enabled via DIP switches. You can use the 3.5mm stereo summing input for connecting an MP3 player or CD/DVD player. A Mic Trim pot is provided for applying up to 20dB of gain to a connected microphone.
  • Channels 5 and 6 are stereo RCA summing inputs for connecting a CD or DVD player.

Speaker Output: The amplifier has a Barrier Strip connector for the speaker outputs. There are connections for a 4Ω direct-coupled speaker load, or 25V and 70V transformer-coupled speaker systems. The Barrier Strip connector will accept up to 12-gauge wire, and is protected from accidental shorting by a clear plastic cover.

Zone 2 Output: The AA400PHD features a Zone 2 output that gets its signal from a selected input for music or messaging on hold applications. The Zone 2 terminal is an unbalanced 600Ω output with a maximum level of 1.0VRMS. A dedicated Zone 2 volume control is provided on the rear panel. The removable 2-conductor Phoenix connector accepts up to 18-gauge wire. DIP switches are provided on inputs 1 through 4 for selecting an input source for Zone 2.

Pre Out Jacks: The Pre Out (RCA) connector allows you to feed a signal to another power amplifier or external audio device. An effects loop can be created by connecting the Pre Out jack to an equalizer or other device, and then back out to the Amp In connector.

Amp Input: The Amp In connector can be used to convert the AA400PHD into a slave amp. When a line level signal is connected to this input, the internal connection between the preamp and internal power amp is broken. The AA400PHD becomes just a power amplifier, amplifying audio signal applied to the Amp In (Pwr In) connector.

Front Panel Controls: The front panel includes a master power switch (push button), a Master Level control, and rotary volume controls for Inputs 1 through 6. The PHD switch is a flush-mounted button that requires a small tool with a point to activate the self-diagnostic test (See Push Here Diagnostic section above). There are status LEDs for Signal, Peak, Limit, and Power.

Bass/Treble Controls: Separate rotary bass and treble controls are provided on the back panel. Normally set at the 12:00 position, the bass control lets you adjust bass frequencies from -6 dB to + 6dB at 100 Hz, while the treble control adjusts treble frequencies from -6 dB to +6 dB at 10 kHz.

Remote Level Control: The Remote Level Control port lets you connect an optional Atlas Sound WPD-RISRL or WPD-VC10K level control. You can control the level of Input 2, Inputs 4, 5, and 6 together, or the Master level. When a remote level control is connected, the system's maximum levels should be set using the front panel level controls, and use the remote potentiometer as an attenuator from the maximum levels set.

Remote Input Select (RIS): With the optional WPD-RISRL wall-mounted remote input selector and volume control, you can select inputs 4, 5, or 6 (but not inputs 1, 2, or 3), and adjust the volume. This is accomplished without having to run an audio signal from the amplifier to the selector, which prevents picking up interference. The WPD-RISRL connects to the amplifier through the RIS and Remote Level connections on the amp, with a maximum range of 200 feet.

DIP Switches: The versatile AA400PHD has individual groups of 4 DIP switches for Inputs 1 through 4 on the rear panel. The DIP switches turn on Phantom Power for Condenser Mics, turn on Mute Receive circuit, assign the input to Zone 2, and select the type of input (mic or line). Another set of 4 DIP switches is provided for Inputs 5 and 6. These turn on Mute Receive for Input 5 and Input 6, assign the Remote Level Port to control Input 4, 5, 6 or Master Level, and turn on Remote Input Select.


  • Frequency Response: 50Hz - 15kHz (0.5% THD)
  • Output Power: 400 watts RMS
  • Dimensions: Width: 16.5", Height: 4.173", Depth: 14.25"
  • Weight: 41.6 pounds

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