Technical information

incorporate class D designs. The jury is out on whether they ultimately offer the
same fidelity as more conventional class A/B designs.
Cliff effect Where the degradation of a signal's reception does not gradually
increase with a reduction in signal quality or strength, but maintains full quality
until some threshold, at which point the signal collapses into incoherence.
Analogue transmissions tend to degrade gradually. Digital transmissions in
modern systems (with error correction built in) tend to maintain full quality, but
then cut out completely at the threshold ‘cliff’.
Clipping When the amplitude of a signal reaches some limit determined by the
equipment in use, it hits a ceiling (and floor) beyond which it cannot proceed. So
the top and bottom of the wave is simply lopped off. The more it attempts to
exceed the limit, the more that's chopped off, and the closer to a square wave the
formerly rounded wave begins to look. This causes it to generate lots of
harmonics, and so it sounds very distorted. The graphic to the right shows a sine
wave at the left, and then the same sine wave amplified by just three decibels, to
the right. This relatively minor clipping generates a third harmonic of 14%, a fifth
harmonic of 3%, a seventh of 1.8% and so on. Truly awful sounding. Clipping is
often caused by turning up an amplifier too loud so that its power limits are
exceeded.
Clocking signal A signal used to synchronise items of equipment which are
communicating digital audio or video signals to each other. The lack of a suitable
clocking signal would allow their timing to drift apart from each other, since their
internal clocking signals would not be identical, so digital samples would be lost.
The effect when using a very high quality clock in audio components such as CD
players, is to produce a high quality sound. The additional costs associated with
this means that only the best CD players (and usually the most expensive)
implement this in their products.
CLV Constant Linear Velocity – as opposed to CAV. A method of spinning a disc
or disk carrying a signal. CLV means that the rate of spin varies in order to
maintain a constant velocity of the track at the point where the reading device is
on the surface. A CD player is an example of this. The CD player runs at about
500rpm at the start of the CD (where the inner grooves are being read), gradually
reducing speed to about 200rpm as the track nears the outer edge.
Coaxial Digital The digital audio output signal of a DVD player in an electrical
format, rather than optical. The data format accords with the S/PDIF
specification.