Seuraava artikkeli on julkaistu
alt.video.laserdisk-uutisryhmässä.
Viestin lähettäjä on Laura Ackley, joka on
aiemmin työskennellyt THX:n
kehitystehtävissä. Siinä
hän korjaa yleisimpiä
väärinkäsityksiä jotka
liittyvät
THX-järjestelmään:
WHAT IS THX?
Hi, I'm Laura Ackley, the THX System Designer. I'm
responsible
for the
design of all professional and commercial THX Sound Systems, so I
thought
I'd try to clear up some of the confusion regarding THX.
THX is a set of implemented design and quality control
standards for
theatre sound presentation. First, the actual physical
theatre
must meet
certain acoustic criteria:
It must have low background noise, (no loud air conditioners
or
projectors), good isolation (so the lucky patron doesn't get to hear
the
gunfight in the theatre next door), and specific reverberant
characteristics based on the volume of each individual
theatre.
Also,
the theatre can't have any nasty slap echoes or reflections.
When an individual theatre meets these standards, it means
that the
dialogue will be more intelligible, the high frequencies will reproduce
clearly, the bass will not build up excessively within the room, etc.
Most of the sound one hears in the movies comes from behind
the screen,
from 3 channels usually. (Occasionally 5, but THAT'S a
different
lecture!)
Because of this, the theatre must also have a good
length/width ratio.
(i.e., No bowling alleys.) From the visual standpoint, this
is
of course
desirable, and from the audio standpoint, it means having a good
"stereo
image" between the left and right channels, so that the patron is
actually hearing in stereo -- in every seat in the house!
Once a theatre is accepted for the aforementioned preliminary
THX
criteria, the owner must choose the equipment to be used from a list
provided by us. This list includes amplifiers, processors,
screen
and
surround speakers. They can choose from a number of different
products
by various manufacturers, but they all the products have been
objectively
tested here to conform to very high standards.
These high-quality components assure a wider dynamic range and
more
faithfully reproduced sound, plus adequate power for the room size.
Incidentally, the ONLY Cinema Processors which were accepted
until quite
recently were made by Dolby, so any THX theatre was by default a
"Dolby"
theatre... and ever-so-much more!
Thus, we're not in competition with Dolby, we're a
COMPLEMENTARY
TECHNOLOGY to Dolby Processing. Recently, Ultra-Stereo also
had
a
processor approved for use in THX Theatres.
Also, we're not in the business of selling any equipment, just
assuring
high quality hardware in THX theatres. The ONLY piece of
hardware
that
is specifically "THX" is an electronic crossover network, which is
LEASED, not purchased by the theatre.
Our design office takes the architectural plans for every
theatre, and
designs the placement of the screen speakers and surrounds.
The
screen
speakers are set in a special baffle structure behind the
screen.
This
structure has certain acoustic properties, and the speaker placement
within the structure is coordinated to best match the projected film
image.
The surround speaker array is designed to provide optimum
sound pressure
and audience coverage. (and to integrate with the interior
design
whenever possible).
We coordinate all this with the architects, owners, and
equipment
installers. Once the theatre has been completed or
successfully
retrofitted, our field technicians visit the theatre to align and
"tune"
the sound system, then they measure the acoustical characteristics
to
make sure that they meet our requirements. This test data is
then
evaluated, and if the theatre passes on all counts, it becomes a
"certified" THX site.
This, of course, entitles the theatre to use the THX name and
show the
THX trailer. (You know, "The Audience is
Listening.") The
theatre is
re-tested every 6 months to ensure that the quality of sound remains
high.
Our "philosophy" is to recreate the film soundtrack mixing
environment
as
closely as possible so that the audience hears the soundtrack as the
film-maker intended. (This is all tied up in a DIFFERENT
lecture
on the
history of film sound....)
In conclusion, we're NOT a method of recording, encoding, OR
processing
movie soundtracks! We're a design and quality control system
for the
PLAYBACK ENVIRONMENT.
This means that EVERY FILM will sound better in a THX theatre,
not just
a
select few. The premium quality of a THX theatre is often
well-demonstrated by "special-effects-extravaganza" films, because
they
are mixed with a very wide dynamic range and a lot of "loud" or "low"
sounds that might distort when played back through a lesser system.
THX theatres are especially well-equipped to handle the
demands of the
new digital theatre soundtracks (like "Cinema Digital" and "SR-D")
because of their high performance and headroom.
SO, that's the scoop on the THX COMMERCIAL THEATRE and
PROFESSIONAL
MIXING ROOM system. The new Home THX system consists of a
family
of
licensed products that various licensees have developed to meet specs.
designated by our engineers. The pricing of the home system
is
dependent
on the licensee. These are sold through dealers like regular
home A/V
equipment, and we do not design these systems.
Thanks for reading, and I hope this helps clarify things!
please note specifically the fifth paragraph from the bottom.
also please
note that Laura Ackley is no longer with THX, and i have also deleted
the
contact information for the THX division. if you have a specific,
industry related need to contact THX you may email me for the address.
also, please note that i am no longer associated with Skywalker sound,
THX, or any other division of LucasArts.
in the words of our bud mcelwaine, widespread distribution and
dissemination of this important information is ENCOURAGED!