139
Additional Information
[4] DTS 96/24
The sampling frequency, number of bits and number of
channels used for recording of music, etc., in studios has
been increasing in recent years, and there are a growing
number of high quality signal sources, including 96 kHz/24
bit 5.1-channel sources.
For example, there are high picture/sound quality DVD
video sources with 96 kHz/24 bit stereo PCM audio tracks.
However, because the data rate for these audio tracks is
extremely high, there are limits to recording them on two
channels only, and since the quality of the pictures must
be restricted it is common to only include still pictures.
In addition, 96 kHz/24 bit 5.1-channel surround is possible
with DVD audio sources, but DVD audio players are
required to play them with this high quality.
DTS 96/24 is a multi-channel digital signal format
developed by Digital Theater Systems Inc. in order to deal
with this situation.
Conventional surround formats used sampling frequencies
of 48 or 44.1 kHz, so 20 kHz was about the maximum
playback signal frequency. With DTS 96/24, the sampling
frequency is increased to 96 or 88.2 kHz to achieve a wide
frequency range of over 40 kHz.
In addition, DTS 96/24 has a resolution of 24 bits, resulting
in the same frequency band and dynamic range as 96
kHz/24 bit PCM.
As with conventional DTS Surround, DTS 96/24 is
compatible with a maximum of 5.1 channels, so sources
recorded using DTS 96/24 can be played in high sampling
frequency, multiple channel audio with such normal media
as DVD videos and CDs.
Thus, with DTS 96/24, the same 96 kHz/24 bit multi-
channel surround sound as with DVD-Audio can be
achieved while viewing DVD-Video images on a
conventional DVD-Video player ( 1). Furthermore, with
DTS 96/24 compatible CDs, 88.2 kHz/24 bit multi-channel
surround can be achieved using normal CD/LD players (
1).
Even with the high quality multi-channel signals, the
recording time is the same as with conventional DTS
surround sources.
What’s more, DTS 96/24 is fully compatible with the
conventional DTS surround format, so DTS 96/24 signal
sources can be played with a sampling frequency of 48
kHz or 44.1 kHz on conventional DTS or DTS-ES surround
decoders ( 2).
1A DVD player with DTS digital output capabilities
(for CD/LD players, a player with digital outputs for
conventional DTS CDs/LDs) and a disc recorded in
DTS 96/24 are required.
2The resolution is 24 or 20 bits, depending on the
decoder.
[5] Home THX Cinema Surround
THX is an exclusive set of standards and technologies
established by the world-renowned film production
company, Lucasfilm Ltd. THX grew from George Lucas’
personal desire to make your experience of the film
soundtrack, in both movie theaters and in your home
theater, as faithful as possible to what the director
intended.
Movie soundtracks are mixed in special movie theaters
called dubbing stages and are designed to be played back
in movie theaters with similar equipment and conditions.
The soundtrack created for movie theaters is then
transferred directly onto Laserdisc, VHS tape, DVD, etc.,
and is not changed for playback in a small home theater
environment.
THX engineers developed patented technologies to
accurately translate the sound from the movie theater
environment into the home, correcting the tonal and
spatial errors that occur. On the AVR-4806, when the
Home THX Cinema mode is on, THX post-processing is
automatically added after the Dolby Pro Logic, Dolby
Digital or DTS decoder:
2Re-Equalization™
The tonal balance of a film soundtrack will be excessively
bright and harsh when played back over audio equipment
in the home because film soundtracks are designed to be
played back in large movie theaters using very different
professional equipment. Re-Equalization restores the
correct tonal balance for listening to a movie soundtrack in
a normal home environment.
2Timbre Matching™
The human ear changes our perception of a sound
depending on the direction from which the sound is
coming. In a movie theater, there is an array of surround
speakers so that the surround information is all around
you. In a home theater, only two speakers located to the
side of your head are used. The Timbre Matching feature
filters the information going to the surround speakers so
that they more closely match the tonal characteristics of
the sound coming from the front speakers. This ensures
seamless panning between the front and surround
speakers.
2Adaptive Decorrelation™
In a movie theater, a large number of surround speakers
help create an enveloping surround sound experience,
while in a home theater there are usually only two
speakers. This can make the surround speakers sound like
headphones that lack spaciousness and envelopment. The
surround sounds will also collapse into the closest speaker
as you move away from the middle seating position.
Adaptive Decorrelation slightly changes one surround
channel’s time and phase relationship with respect to the
other surround channel. This expands the listening position
and creates—with only two speakers—the same spacious
surround experience as in a movie theater.
