Edwards EST3 3-ZA20A-E Zone Amplifier, Class A 20 W

A 20 W zone amplifier that drives one paging zone of the EST3 voice evacuation system; it can drive the loudspeaker line with a Class A (Style Z) connection. According to the manufacturer's datasheet the speaker output is selectable for 70 V or 25 V, and loudspeaker taps are chosen for that line voltage. When a break occurs on a Class A line, the broadcast continues from the other end of the line, which prevents a single damaged cable from silencing an entire floor. The number of zones and the loudspeaker load determine how many amplifiers are needed.