Technical information

excursion is necessary because output level is related to the area of the cone and
the excursion. A smaller driver in a subwoofer can only provide equivalent output
levels by allowing a greater excursion of the cone. Another example of excursion
is the stylus of a cartridge. When playing a stereo LP it moves from side to side
and up and down. Each of these is referred to as the excursion (horizontal and
vertical) of the stylus.
E
Efficiency Used in connection with transformation of energy from one form to
another, efficiency is the ratio of energy output to energy input in the
transformation process. In regard to speakers, it is normally expressed as
speaker sensitivity.
Electrostatic loudspeakers A form of loudspeaker in which the driver is a panel
that responds to a varying electrostatic charge. Such speakers incorporate
electronics which convert the moderate voltage, moderate current output from an
amplifier into the high voltage, low current signal required to drive the panels.
Electrostatic speakers are noted for producing little harmonic distortion and an
excellent amount of detail in the reproduction of music. However they often
present a difficult load upon amplifiers, can be subject to arcing (producing
electrical sparks) in high humidity situations and tend to be somewhat inefficient.
Because they use a large panel, these speakers do not employ an enclosure and
so are bass limited. For this reason many models are hybrid, with standard
woofers in an enclosure for bass. Electrostatic speakers are by their nature
dipolar in operation since each side of the panel is generating an out-of-phase
sound wave to the other.
Enclosure The box of a loudspeaker. In any half decent speaker, this is not merely
a device to keep the drivers off the floor, but an integral part of the design of the
whole loudspeaker, contributing greatly to -- or, if done badly, detracting from -- its
performance. The most common enclosure designs are bass reflex and acoustic
suspension. Good quality enclosures include strong bracing to resist sympathetic
vibrations in their panels, which can lead to sound colouration.
Error correction Redundant data included with a signal in transmission or storage
that allows the signal to be reconstructed even if some data has been damaged or
lost. Error correction is used in most digital systems, from CDs through to digital
television.