Audio amplifier powered over Ethernet A study of using IEEE 802.3at Power over Ethernet as a power source for a class-D audio amplifier.

Abstract

Today, a professional amplifier may be supplied with its input as well as control and monitoring via Ethernet. By Power over Ethernet (PoE) it is now possible to provide its power as well. It means that an amplifier can be fully operating with a single cable. Power over Ethernet is standardized by IEEE and it allows 25-34 W to be distributed over a twisted-pair Ethernet cable. As a proof of concept, a PoE amplifier is created and evaluated. The performance of the amplifier is analyzed to determine if PoE is suited for powering amplifiers. The amplifier is measured both when it is powered over Ethernet and when it is powered with a regular power supply unit. The result is compared to determine what impact PoE has on the output audio quality. The PoE amplifier is able to deliver 25 W of continuous output power and it can deliver up to 81.8 W when playing a “music like” signal with good audio quality. For lower level output there is no impact in the audio quality on the PoE amplifier but for higher output power the amplifier loses some of its linearity.