Electro-Voice 840 is a solid-state background music receiver that combines a sensitive Hi Fidelity FM Tuner and a 30-watt audio amplifier. It features a microphone pre-amplifier, external amplifier jack, crystal phono jack, Multiplex Converter jack, and microphone jack. With speaker outputs for 8 ohms, 25 volts, and 70 volts, it offers versatile connectivity options. The unit also includes a microphone precedence circuit for suppressing the music channel during paging.