Technical information

that very modest figures like -20 or -30dB (typical of LP records) provide excellent
stereo separation and imaging. More important is that the separation should not
vary widely between different frequencies, since this could lead to a positioning
mismatch between the fundamental and harmonic frequencies for particular
instruments.
Server (music) A computer device dedicated to the storage and analogue
production of music from its library held in digital form on its hard disk. There are
many variations of server available for audio, from dedicated software enabling any
home computer to ‘serve’ music, to dedicated hardware and software products
offering the highest level of audio replay.
Shielding A finely woven mesh of thin wires, or a conductive foil wrapping, around
a signal cable under the outer layer of insulation, or solid in the case of
transformer shielding. The shielding is earthed and acts to protect the signal-
carrying wires within from electrical fields which could introduce noise into the
signal.
Signal to noise ratio A specification for the level of noise produced by a system.
This is normally expressed in the decibel difference between the measured noise
and some reference signal.
Sine wave An electrical signal or tone that follows a sinusoidal shape. The shape
is ubiquitous in nature. All repeating waves can be generated by a combination of
a sine wave with various harmonics of that wave.
Skate The tendency of the stylus of a turntable cartridge to seek to slide towards
the centre. This is due to the geometry of the tone arm and results in a greater
force being applied to the inner side of a groove than the outer side. Tone arms
have an anti-skating device fitted to prevent this problem.
Smart Media A small, removable flash memory (i.e. non-volatile) cartridge, used in
a host of digital storage situations, notably in digital cameras and digital audio
players. It should be noted that many MP3 players reformat Smart Media cards
in a way that will not permit them to be compatible with digital cameras.
SNR Signal to Noise Ratio See Signal to noise ratio.
Sound Stage A movie set where audio is recorded along with video. But in the
home entertainment (audio) context, the sound stage is area between a pair of
stereo speakers from which they appear to make the various sounds appear.
High quality audio systems will make the sound stage actually wider than this
space, and provide sensations of both vertical sound placement and depth in the
stage, offering a ‘holographic’ or multi-dimensional audio effect.