Technical information

higher horizontal resolution of around 300 lines, compared to VHS' 250 lines),
which had beaten it to market. Eventually VHS prevailed through having longer
record-playback times. There was also an electrically similar, but physically
smaller, compact version of VHS called VHS-C for use in digital video cameras.
Superseded by DVD-R.
Voice coil The coil of wire that is attached to the back of the cone or dome of a
loudspeaker driver. This is surrounded by a strong, close magnet so that when
electricity is fed into the coil, it moves to and fro, moving the attached cone or
dome to and fro, generating sound.
Volt The standard unit for electrical potential.
W, X, Y, Z
Watt A unit of power. For DC, it is equal to the current multiplied by the voltage
(one watt equals one volt times one amp).
Wavelength The end-to-end physical measurement of a cycle in a repetitive signal,
measured in metres (or convenient multiples). Audio wavelengths are generally in
the range of 17mm to 17 metres (at air temperature 20C). The human eye
responds to light in the wavelength range of 380 to 780 nanometres. The
wavelength of a signal can be calculated by dividing the speed with which the
signal propagates through a medium by its frequency.
White noise Random audio noise where the average amount of power is the same
across all audio frequencies. Sometimes used as a test signal, but it is weak
because real audio has power characteristics more like pink noise.
Woofer The largest driver in a loudspeaker enclosure, sometimes called the bass
driver. This provides the bass sounds while the higher sounds get routed by the
crossover network to the midrange driver (if any) and tweeter. Many modern
loudspeaker designs use two or more smallish woofers rather than one large one,
which is more consumer friendly (smaller enclosures), but less able to offer high
impact dynamics.
Wow A defect affecting analogue audio signal sources that rely on rotating the
medium, particularly LPs and compact cassettes. Wow is a slow, repetitive speed
variation, typically repeating at less than once per second. If an LP or audio
cassette undergoes this, it produces slow variations in the playback frequency.
Wow is specified in per cent and specifications of more than around 0.1% are