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article last updated on
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format 
 So you're ready to take your next step into the world of
home
theater, or
you're thinking about upgrading to a Dolby
Digital and DTS
capable home theater
receiver. Great! With this buying guide, we can help you shop
intelligently for a home theater receiver that best meets your needs. In conjunction with reading this guide, you may wish to read our
Surround Sound
Formats Primer and THX
Overview. What Is a Receiver
and What Does It Do? First, let's answer the question:
"What is a home theater receiver and what does it do?" A home theater receiver
serves as the central point of a home theater or home audio system and
performs the
following functions:
The receiver is both the
"smarts" and the "power" behind a home
theater system. It takes the audio signals from all of your source
components (e.g., DVD-Video player, CD player, VCR, tape deck, turntable), performs any needed
decoding and post-processing, amplifies the signal to power your home theater's
array of loudspeakers, and controls the playback volume. For video
signal, the receiver performs the necessary switching and outputs it to
your TV. With all this
functionality, a receiver is one of the more complex and
expensive components in a home theater or home audio system.
The terms "home theater
receiver", "audio/video receiver", "A/V receiver", "surround receiver",
"Dolby Digital/DTS receiver", and "receiver" are used interchangeably
on this web site,
since we're talking about a receiver that has at least five
channels of processing and amplification for home theater and multi-channel
music sources such as DVD-Audio
and Super Audio CD. If
you're not familiar with all the terms we just threw out, don't
worry. We'll discuss
each of these functions in turn. Then we'll tell you what else you
should look for, and
how to compare and audition A/V receivers when you shop.
Surround Sound Decoding Right
off the bat, let's discuss a receiver's surround sound decoding functions.
Surround sound is encoded in the source material and must be decoded into their
separate channels to drive separate loudspeakers. The current de facto
standard for surround sound is 5.1-channel
(Dolby
Digital and optionally DTS).
6.1-channel
formats are available but few movies and DVDs are encoded with these extended
surround sound formats. A receiver should come
with decoding for the following surround sound
formats, as an absolute
minimum:
-
 Dolby Surround Pro-Logic: This surround sound format
is used in Hi-Fi
VHS and analog TV broadcasts dating back to 1987. It matrixes
(folds in) the center channel information into the left and right main channels. The
surround channel signal is mono (1-channel) and is bandwidth limited, with
only frequencies between 100 Hz and 7,000
Hz. The surround sound channel
is also encoded into the main left and right channels.
-
 Dolby
Digital: The de facto surround sound standard
for all DVD-Video soundtracks and digital TV (HDTV) soundtracks. This
flexible surround sound encoding algorithm allows up to 5.1 channels of
a surround sound soundtrack
to be discretely
(independently) encoded. This provides better localization of
sounds anywhere in the five loudspeaker locations. Read
more about Dolby
Digital here.
-
 DTS
Digital Surround (DTS): A competing surround sound
format to Dolby
Digital that can also support up to 5.1 channels of audio.
DTS uses higher data rates to encode the same soundtrack
information. Some home theater enthusiasts believe that DTS
soundtracks sounds better than that of Dolby Digital.
Unfortunately, however, DTS is an optional soundtrack and is found on
few DVD-Video titles. Read
more about DTS
here.
"5.1-channel ready" receivers. This type of A/V receiver does not have built-in
decoding for any of the 5.1-channel surround sound formats such as Dolby Digital or
DTS. Instead, this type of receiver provides 5.1-channel analog input
jacks and depends on
the another component (e.g., DVD player or separate decoder) to perform the decoding for Dolby
Digital and DTS. State-of-the-art receivers will include
decoding for one or more of the following, in addition to the list above:
-
 THX Surround EX
or Dolby Digital EX: A
relatively new Extended
Surround "6.1"-channel format that is based on Dolby
Digital. The addition of one or two back surround speakers allow
complete 360° of envelopment. The back surround audio channel
is matrix encoded into the left and right surround channels, and is
therefore not a true discrete 6.1-channel audio format. Few
movies are produced and consequently few DVD-Video titles are released
with this new surround sound format. Read
more about THX Surround EX
or Dolby Digital EX here.
-
 DTS-ES Matrix: Another
relatively new Extended
Surround "6.1"-channel format that is based on DTS.
DTS-ES Matrix is similar to Dolby
Digital EX in that the back surround audio channel is matrix
encoded into the left and right surround channels, and is therefore
not a true discrete 6.1-channel audio format. Very few DVD-Video
titles are released with DTS-ES Matrix surround sound option. Read
more about DTS-ES Matrix here.
-
DTS-ES Discrete 6.1: This
DTS-based Extended
Surround format is a true discrete 6.1-channel format, with a discretely
encoded (not matrix encoded) back
surround channel. This provides the ability to precisely
place surround sound effects behind the audience. Unfortunately,
only a handful of DVD-Video titles are released with DTS-ES Discrete
6.1
surround sound option. Read
more about DTS-ES Discrete 6.1
here.
-
 Dolby Pro Logic II
(DPL II): As its name implies, DPL II is the newer version of the original Dolby Surround Pro
Logic. In Movie mode, it provides better decoding of legacy Dolby Surround Pro
Logic with its advanced digital signal processing and steering
logic. Decoded surround channels are discrete
and are full frequency (20 Hz
to 20 KHz). In Music mode, DPL II works with any ordinary stereo audio source,
converting 2-channel audio programs into 5.1-channel
surround sound for a compelling multi-channel
audio experience. This is a great feature that allows you to
enjoy stereo sources in the glory of 5.1-channel surround sound.
-
 Dolby
Headphone: This powerful digital signal processing algorithm
simulates the acoustic soundscape of a 5.1-channel home theater
surround sound loudspeaker system through the use of an ordinary
pair of stereo headphone. If the receiver has this feature, all
you need is any ordinary set of headphones to enjoy Dolby Headphone
(no special headphone required). Read
more about Dolby
Headphone here.
-
 DTS
Neo:6: Similar to Dolby Pro Logic II, DTS Neo:6 decodes Dolby
Surround Pro Logic matrix-encoded stereo source into 5.1-channel or
6.1-channel. DTS Neo:6 can synthesize the back surround channel
from 5.1-channel sources. In DTS Neo:6 Music mode, 2-channel audio programs
are converted into 5.1-channel or 6.1-channel surround sound for a compelling multi-channel
audio experience.
-
THX Ultra2 Cinema mode and MusicMode: In
Cinema mode, THX Ultra2 converts Dolby Surround Pro Logic
matrix-encoded stereo and 5.1-channel soundtracks into 7.1-channel
soundtracks. In MusicMode, 2-channel audio programs are
converted into 7.1-channel
surround sound for a compelling multi-channel
audio experience.
For
a home theater receiver, Dolby Digital and DTS decoding are must-haves.
Then consider Dolby Pro Logic II and DTS Neo:6,
followed by THX Surround EX (or
equivalently
Dolby Digital EX) and DTS-ES surround sound decoding.
Be sure to read our
Surround Sound
Formats Primer to fully understand the different surround sound formats discussed above.
Next: Audio Signal
Processing >>
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