Cambridge Audio Stereo Integrated Class XD Amplifier Azur - 851A

Class XD amplification designed to eliminate crossover distortion at low signal levels

Available in black and silver finishes

Class XD

Class XD, a proprietary Cambridge Audio technology, is a unique amplifier circuit design created to offer the optimum sound quality currently available from existing amplifier configurations, whilst retaining the high power levels required for truly dynamic performance. It was conceived by our London-based engineering team to combine the best of both worlds from Class A and Class A/B amplifier operation.

Class XD (crossover displacement), gives the benefits of pure Class A operation at low levels and eliminates the distortion associated with conventional Class B operation as the fragile audio signal passes though the zero crossing point from transistor to transistor. Distinct from Class AB, XD technology feeds a controlled current into the output stage in such a way that the usual Class B crossover points no longer occur either side of zero volume - the worst possible position in terms of distortion – but displaced to a point where the transfer functions of the transistors are better matched, at a significant output level where it is less audible. The system operates outside of the feedback loop so is not directly involved in the signal amplification itself.
 The result is a smooth and linear transition between the two key operating modes, Class A and B.

The benefits of this approach give the sonic refinements of Class A operation and the uncompromising efficiency and power of Class B operation. In fact, the new 851A delivers a gigantic 120 watts per channel - enough for the most demanding speaker set-up.