Product Specification Sheet APS373

Rev. 07/2013

931 System Amplifier/Power Supply

  • Easily Installs Right on Finished Wall Surface or in Customer Supplied Housing
  • Only one power supply required per system.
  • Clear Voice Fidelity with Adjustable Voice Volume Control
  • Convenient Positive Screw Terminal Connections
  • Operates on standard 120VAC primary power
Architects' And Engineers' Specifications

The power supply/amplifier shall be Alpha Communications® / Elvox™ model 931, or approved equal. Amplifier shall operate from a standard 120VAC power source. All other wiring to power supply/amplifier shall be low-voltage Class II wiring, installed as per all federal, state, and local electrical codes. Power supply/amplifier shall surface mount right to the finished wall and shall be installed in a suitable environment that is free from excessive dirt, dust, temperature, humidity, grease and water. Power supply/amplifier shall provide the intercom amplification and signaling power for proper system operation. For most secure installation, power supply should be installed into a lockable equipment cabinet / housing. The 931 is designed to be used with the 870W, 8870 and 902 series apartment handset intercom units (or equivalent). 

Power supply/amplifier shall be installed a safe distance from any source of electrical interference. 

Contractor shall observe all local and national electrical and building codes.

931 Amplifier/Power Supply

The Alpha Communications® 931 amplifier/power supplies are used with the 870W, 8870 and 902 series handset intercom stations (or equivalent), to provide intercom amplification, power to operate the electric door opener(s) etc., and power to signal the handsets from the lobby entrance station. 

The 931 units each require a standard 120VAC power source. 

These 931 amplifier/power supplies are designed to easily surface mount right onto the finished wall by means of customer supplied screws. Connections are positive screw terminal type. 

Only one (1) 931 is required for each system, regardless of the number of handsets in the building.



Height: 2.55" (65mm)
Width: 5.50" (140mm)
Depth: 4.55" (116mm) from mounting surface

Volume Control:
Adjustable potentiometer built-in.
Positive Screw Terminal Connectors.


Wiring Requirements

Basic intercom riser wiring shall be 4-common #22AWG, 2-common and 1 selective wire #22AWG, for each handset station on the riser. Add one (or more) additional common wires if other handset functions will be used. See system wiring diagram(s) for more complete wiring information.

Optional Components

16VAC Door Release-Mortise Type
Dual Entrance Dual Video Adaptor
(requires 2/690 connector cable)
Specialty Door Opener Relay Adaptor
(1 per entrance)
Alpha Communications
42 Central Drive • Farmingdale • NY • 11735-1202 • Phone: (631) 777-5500 • Fax: (631) 777-5599
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Due to continuous product improvement, all colors, sizes, materials, finishes and specifications are subject to change without notice.