Technical information

S-VHS tape recorders, and the TVs for them to plug into. Sometimes the term S-
VHS is incorrectly used instead of S-Video.
Sweet spot The seating position or positions at which a stereo or surround sound
system produces its best effect, particularly with regard to imaging.
T
Theile and Small parameters Back in the 1960s the Australian engineer Neville
Theile and American engineer Richard Small developed a method of modelling
loudspeakers, allowing the bass performance of loudspeakers to be explicitly
designed, rather than developed through trial and error. Forty years later, their
work remains the basis of loudspeaker design. To use their design techniques a
number of characteristics of the woofer to be used must be known. These include
such things as the driver's resonant frequency, its compliance, its 'equivalent
volume' and so forth. These are collectively known as the Theile and Small
parameters and are stated by all reputable driver makers.
Three-way loudspeakers A loudspeaker which divides the incoming signal into
three different frequency bands for distribution to drivers. It sends high
frequencies to the tweeter, the middle frequencies to the midrange driver, and the
low frequencies to one or more woofers.
THD Total Harmonic Distortion See total harmonic distortion.
THX A certification standard controlled and operated by LucasFilm. It covers
certification of both cinemas and home entertainment equipment to meet given
minimum standards. Originally, on the home entertainment front, there was just
one standard: 'THX Certified'. But in recent years this has been replaced by two
standards: 'THX Ultra' certification, which is the highest level and is similar to the
old standard, and 'THX Select' which is a lesser standard. Note that many brands
and products which could easily achieve THX certification decline to seek it for
reasons of brand self-respect, or to avoid the cost involved, so THX certification
does not necessarily mean that a piece of equipment is superior.
Time alignment Systems for ensuring that audio signals from various
loudspeakers or drivers arrive at the listener at the correct time. For example,
high end loudspeaker makers will recess the tweeter further into the enclosure to
ensure that the high frequencies arrive at the listener at the same time as lower
frequencies, with a view to delivering a more coherent sound. With surround
sound it is important that the sound from the surround speakers does not arrive
early, even though these speakers are often situated closer to the listener than