Acoustic energy distribution in space around the pipe outlet

The class-D power amplifiers which operate in a switched mode have become an attractive alternative of the conventional analog power amplifiers class-A, B and AB in the field of audio applications. They offer high power efficiency compared to analog power amplifiers and can be realised as completely digital power amplifiers. This paper briefly overviews the basic concepts of analog and digital power amplification using the pulse-width and sigma-delta modulation techniques as well as novel approach based on a click modulation technique and class-D power stages.