X-Over Distortion

An abbreviation for “crossover distortion,” which is a type of distortion pertaining to anomalies that occur when a signal “crosses over” from the positive portion of its waveform to the negative portion in audio circuits. It is most widely known as a phenomenon of push-pull amplifier designs where separate banks of output devices handle each half of the waveform. There is a region near zero where the signal is transferred from one to the other that, if not done smoothly, can produce a discontinuity in the audio that sounds a bit like harmonic distortion. Since this distortion is at a constant level it is much more obvious at low levels. As such crossover distortion is most thought of as a problem only with low-level signals. Digital converters are also sometimes plagued with this problem, though for different reasons. In digital it is more a manifestation of quantization error at low bit depths.