Transmission of power and/or signalling between an audio distribution unit and a plurality of remote audio transducers

Abstract

A remote-controlled audio system comprises sets of loudspeakers (A-D) connected to power amplifier units (A-D) in an audio distribution unit () to which several audio sources, such as a compact disc unit, a tape deck, etc., are connected. Remote units () are provided, one in each zone with a set of loudspeakers. The loudspeakers and the remote unit are connected to the audio distribution unit by four wires whereby audio and data signals and power are transmitted to the loudspeakers and the remote unit, respectively. Each power amplifier unit may have a pair of power amplifiers, each connected to one of the loudspeakers in the set, referenced to a first ground () and a second ground (), respectively. The second ground () is maintained at a prescribed voltage relative to the first ground. The remote unit (A) is connected between the 'ground' terminals of the two loudspeakers of the set, i.e. those connected via the speaker cables to the first and second grounds in the audio distribution unit. The remote unit has a transmitter unit which transmits control signals to the audio distribution unit via the 'ground' cables. In the audio distribution unit, an interface circuit connected between the grounds conveys the control signals to a control device which adjusts the settings of the audio distribution unit in dependence thereupon. The remote units may receive power from the audio distribution unit via the transmission channel to supply their internal components.