The THX logo has labeled a
profusion of audio and video product for decades. Yet
many folks wonder, what is THX? THX is simply home
theater standards that manufacturers and installers must
meet to be THX certified. THX's goal, recreate the THX
commercial theater experience.
THX, originally a division of
Lucasfilm, is now an independent company. THX is not a
standard such as Dolby or DTS. Yet THX does outline
minimum specifications for amplifiers and speakers such as
flat frequency response, low distortion, and low
noise. In addition, THX makes the following
assumptions:
- Many movie soundtracks mixed with a mid-range boost cause
harsh-sounding playback in a home theater.
- Acoustical reflections from the floor and ceiling smear
sound fields and distort the mid and higher frequencies.
- Compromised speaker placement stimulates room modes that
distort audio.
- Listener placement near room boundaries creates excessive
bass.
- Rear channel effects are often unconvincing via dated
surround sound encoding.
As a result, THX standards institute the following
modifications to the electronic processing and the speaker
system.
- THX processing features 'ReEQ' and 'Timbre Match' that
alters high frequency and mid-range output, which results in
less harsh sound.
- THX standards decrease vertical dispersion of the front
speaker system, which should result in less distorting
acoustical-reflections from the floor and ceiling.
- THX specifies smaller front and rear speakers with
processing that re-routes low-frequency sound to a
subwoofer.
A single source of low bass, the subwoofer,
simplifies the management of distorting low-frequency room
modes.
- THX adds 'Boundary Gain Compensation' that filters
excessive bass for seating near a room boundary.
- THX implements an optional rear dipole speaker design,
which creates a more-diffused, less localized sound.
- THX offers 'Adaptive De-correlation', which creates a more
spacious image from older rear channel sound mixes.