The analysis, design and testing of a parallel switching/linear hybrid audio power amplifier rated at 100 W into 8 Ù are presented. The amplifier employs a hysteretically controlled switching stage and high-bandwidth linear amplifier whose high-gain negative-feedback loop controls the output signal. The majority of the output current is provided by the switching stage, enhancing efficiency. The amplifier’s fidelity has been tested with standard commercially available equipment, whilst efficiency has been evaluated across a very wide range of signal and load conditions using a custom active-load and automated test procedure. The combined fidelity and efficiency test results are analysed, and the suitability for domestic applications of this amplifier configuration discussed.
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