Patent ID: 9131306
Filing Date: 2015-09-08
Classification: H04R

Abstract:
1. An audio appliance comprising at least one audio output including at least two external terminals for connection to one or more external loudspeakers for playing back via each external loudspeaker a sound signal corresponding to an audio source amplified by the appliance, the appliance including means for establishing between the external terminals an electrical signal representative of the audio source for injecting a corresponding electric current into each connected external loudspeaker, the appliance including means for incorporating an electrical signal component having a “detection” frequency that lies outside the audible frequency spectrum in the electrical signal established between its external terminals, and also means for detecting an electric current flowing between the external terminals and having a component of frequency that corresponds to the detection frequency, wherein the appliance includes a class D amplifier for amplifying the sound source, and in which the component of the electrical signal having the detection frequency as its frequency is generated directly by the class D amplifier, the detection frequency corresponding to a sampling frequency of the class D amplifier.