The Medusa 3 Series was developed with a clear objective, a Public Address System that was reliable and easy to use. A single box solution suitable for virtually any small-to-medium scale Public Address system application. The Medusa 3 Series consist of the Master Unit with a built in power amplifier making it an extremely easy to deploy standalone PA System. The Master unit is also versatile and provides up to 12-zones coverage. The Master Unit can be expanded with a Slave Unit, increasing the systems amplification power as well as zones up to a maximum of 24-zones. The Medusa 3 Series can be complimented with a Medusa MEI 60 Automatic Evacuation Interface, allowing for a fully automated ‘sandwich’ (N+1, N, N-1) evacuation with built in message. The Medusa 3 also comes with a built in amplifier monitoring and automatic changeover circuit to switch over the internal Master or Slave power amplifier to an external standby amplifier upon failure. Coupled with a built-in siren and handheld emergency microphone the Medusa 3 Series satisfies the growing need for building evacuation systems.