Technical information

EQ Equalization. An adjustment to the frequency response of some piece of
equipment or process in order to achieve a desired outcome. It might be part of
a standard process (eg.RIAA Equalization) designed to overcome physical
limitations, or it might be used to correct unwanted frequency response
inaccuracies imposed by a room.
Excursion The degree of fore and aft movement of a mechanical component in an
audio system. Loudspeakers, for example, produce sound by vibrating their
drivers' cones or domes. The distance between the furthest the cone, say,
protrudes forwards and the furthest it moves back into the housing is the
excursion of the driver. Woofers tend to have a greater excursion than drivers for
higher frequencies. The drivers in some compact subwoofers deliver an excursion
of up to 50mm. This wide 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.
F
FFT Fast Fourier Transform. A set of mathematical techniques for deriving a
close approximation of the Fourier series for a real-world signal so that processing
can be performed upon it. FFT is, with suitable hardware, sufficiently fast to allow
real-time processing of signals. DSPs are based upon its mathematics (although,
of course, they also do much processing work on the result of the FFT as well).
Firewire Apple Computer's name of a high capacity digital connection standard,
capable of delivering up to 400mb/s. Frequently used for transferring video and
audio from digital video cameras to DVD recorders and computers. Also known
as IEEE1394 (the formal name) and i.link (Sony's name).
Fletcher Munson curves Experimentally derived results which plot the perceived
loudness (by humans) of sounds across the audio spectrum. These suggest that
our ears are very much more sensitive to midrange and low treble sound than
they are to the bass and treble frequency extremes. The peak sensitivity occurs
at around 4,000 hertz.
Flutter A defect affecting analogue audio signal sources that rely on rotating the
medium, particularly LPs and compact cassettes. Flutter is a rapid, repetitive
speed variation, typically repeating at least ten times per second. If an LP or