Class-XD Amplifier

Class XD (crossover displacement) is a proprietary and patented amplifier technology developed in-house by Cambridge Audio.

First appearing in 2006 in the Azur 840A integrated amplifier, the Crossover Displacement design sought to combine the performance of a traditional Class A design with the efficiency of Class B but without the linearity and distortion limitations of Class AB. In Class A amplification the output transistors are modulated by the audio signal to turn more or less ‘on’ but never actually turn off. However, in Class B the output transistors actually turn off at some point as the output is passed from one transistor to another. In the point at which the output moves from one transistor to another (the crossover point), a small amount of distortion is created. "This crossover distortion is inevitable and although it can be minimized, Cambridge's Class XD alternative doesn't eliminate crossover distortion, it shifts it away from the zero-crossing point of the waveform."