article last updated on 6.5.2002
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So you're ready to take your next step into the world of
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 an audio/video (A/V) receiver that best meets your
needs. This essential guide is tailored for receivers less
than $750. If you want to read a more complete version or are
considering receivers well over $800, our more complete Home
Theater Receiver Buying Guide may be more suitable for your
purpose. In conjunction with reading this guide, you may wish to read our
Formats Primer and THX
What Is a Receiver
and What Does It Do?
First, let's answer the question:
"What is an A/V receiver and what does it do?" A home theater receiver
serves as the central point of a home theater or home audio system and
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
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
Digital and optionally DTS).
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
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.
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 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
"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
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
surround sound option. Read
more about DTS-ES Discrete 6.1
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.
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
an A/V 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
Dolby Digital EX) and DTS-ES surround sound decoding.
Be sure to read our
Formats Primer to fully understand the different surround sound formats discussed above.
A receiver may perform a number of audio signal
processing functions, depending on the input source and depending on user
preferences. These include digital audio (PCM)
decoding, simulated soundfields, bass
management, and THX post-processing.
Audio (PCM) Decoding
For digital sources
like audio CD, you can connect the CD player using a pair of analog stereo
connectors. In this case the audio signal is already converted from
digital to analog form by the CD player and no further decoding is
required. Alternatively, you can use the CD player as a CD transport and hook it
up to the receiver using the digital audio output.
If you use the digital audio connection, then the receiver's audio digital-to-analog converter (DAC) is used to convert the raw
Pulse Code Modulation (PCM)
digital audio signal to analog. The receiver's audio DAC is usually
24-bit word length and samples at 96 kHz. Better receivers will have audio DACs with higher
sampling rates (up to 192 kHz), or quality audio DACs made by Burr-Brown or
Analog Devices. Unless you have a high performance
audio CD player or any digital source with high quality audio DACs, we recommend
that you connect the CD player to the receiver via one of the digital audio
connections. This will allow you to use the receiver's
audio DAC and simultaneously minimize
degradation that usually plagues analog connections.
Many receiver manufacturers include a number of
simulated soundfields (sometimes referred to as DSP modes) effects to imitate the
acoustic environment of various real-world venues (e.g., jazz club, concert hall, cathedral,
stadium) by adding synthesized early reflections and reverberations. While listening to these soundfields can be fun, audio purists will find
little value with these simulated soundfields as they do not serve the
artists' or performers' intentions. And while it's
nice for receivers to include this feature, it should not become a primary
consideration when choosing among different receivers.
The receiver's bass management
function re-directs the bass frequencies from any channel to those
can handle the low frequency bass information (e.g., full-range floorstanding loudspeakers, subwoofer).
This ensures that the
low frequency audio signals are not lost when you're using a system of bookshelf or
satellite speakers. If you have five full-range loudspeakers and a
subwoofer (few of us do), bass
management is not a concern. But if you don't, it is essential that
you look for a receiver with complete bass management functionality. With bass management,
you set up your system by telling the receiver whether you have large
(full range) or small (satellite or bookshelf) loudspeakers for the center
channel, the two front left/right mains, and the surround sound
Editor's Note: If you plan to
adopt the new high resolution, multi-channel DVD-Audio and
Super Audio CD formats, you will also need bass management if you have
small bookshelf, satellite, or surround speakers. When buying a DVD-Audio player or SACD
player, look for one that has full bass management functionality, because
few receivers offer an appropriate bass management function for these high
resolution audio formats.
may have heard "more power is better" when it
comes to receiver amplification. Well, we're here to tell you that
it's pretty much true (to a certain extent)! But here's the kicker: there are a few other facts you must
know and consider in choosing the amount (and quality) of amplification that you will need.
Amplification is the process where a receiver takes a low voltage analog audio signal
(usually a few Volts) and amplifies it to a powerful analog signal with
enough current to control and drive the loudspeaker's array of drivers to
produce the sound that we hear. First, we'll talk about the
number of channels, then how receiver
amplification power is specified and how much
power you will need.
As we mentioned above, the current
de facto standard are the 5.1-channel
surround sound formats such as Dolby
Digital and DTS.
This means 5 channels of full
frequency, plus a single ".1" low
frequency effects (LFE) channel for an optional subwoofer.
5.1-channel receivers have 5 channels of amplification for the full frequency
channels, while the ".1" subwoofer output is not amplified
for use with an active subwoofer (one with a built-in power amplifier) or a
passive subwoofer in conjunction with a separate amplifier.
new and emerging surround sound formats are the 6.1-channel
surround sound formats, with the addition of a full-frequency back surround
channel. Though there is a single audio signal for the back surround,
two loudspeakers driven off of that signal is usually recommended for a more
continuous soundfield. So if you are considering the 6.1-channel
formats, many mid-priced receivers will have 6 channels of built-in
amplification, some with an option to use a separate power amplifier for the second
back surround loudspeaker. The more expensive receivers will have 7
channels of built-in amplification to allow the use of two back surround
loudspeakers. In any case, the ".1" subwoofer output is not
There are a number of
aspects to a receiver's power rating, all of which should be considered
Power. Amplification power is usually given in units of Watts (just as the wattage of a light bulb
is a general indicator of how much light the bulb can emit). Since music
and movie soundtracks can have long loud passages, we are interested
in how much power a receiver can continuously put out to drive the
loudspeakers during these extended demanding aural passages. For this reason, we should not be interested in the peak power of a receiver,
the amount of power a receiver can deliver for a very brief duration before
running out of "steam". Rather, we are interested in a
receiver's continuous power output, which ensures that the receiver will have
enough "steam" to drive the loudspeakers during long passages of
demanding audio material. Continuous power is usually expressed in terms
RMS" (root mean square) or "Watts continuous". Do not
give credence to or compare receivers based on power specifications that say "Watts peak".
Range. Ideally, our ears can hear sounds as
low as 20 Hz (bass frequencies) to as high as 20,000 Hz
(treble frequencies). This full
range of audio frequencies should be reproduced by a home theater
system. In doing their part, receivers should be adept at amplifying audio signals in the full
range of 20 Hz to 20 kHz in order to maintain a realistic reproduction of
music and movie soundtracks. The frequency range portion of a receiver's
power rating is usually given as "20 Hz to 20 kHz", or equivalently
"full bandwidth". Anything
less than this range of frequencies is unacceptable.
Simultaneously. Movie soundtracks often have loud passages where
all channels (center, left, right, left surround, and right surround) erupt to
loud sound levels. These loud passages are very demanding as all
5-channels are driven hard at the same time. Better home theater receivers
will have power specifications that say "all channels driven
simultaneously" for the rated power output. Those receiver with
specifications that don't say "all channels driven simultaneously"
are likely to provide the rated power output for only one or two channels
driven simultaneously. Like the continuous
power specification, those that lack this capability may run out of "steam"
during loud passages where all channels are driven hard. But this
specification is less important between the two. Only high performance
receivers will have "all channels driven simultaneously" in its
power rating, so unless you're in the market for a receiver of that caliber,
this is something you can forego.
Most loudspeakers have a nominal impedance (or resistance) of 8 ohms.
Some will have a value of 4 ohms, which means that they will draw twice as
much current from receivers than those with 8 ohms (assuming all else are
equal). Most receivers have no problems driving loudspeakers with 8 ohms
nominal impedance, but only some have enough "juice" to
effectively drive the more demanding loudspeakers with 4 ohms nominal
impedance. Most receivers are specified with power output "into 8
ohms". If you have a loudspeaker with 6 ohms or 4 ohms nominal
impedance, look for receivers that specify power output "into 4
ohms". Those that only specify "into 8 ohms" will still
drive 4-ohm or 6-ohm loudspeakers, but its performance will be much less than if
they were driving 8-ohm loudspeakers. Additionally its power output into
the 4-ohm loudspeaker will not be known. If you have 4-ohm loudspeakers, it
would be ideal if a receiver's specification give two numbers, one for 8-ohm
loudspeaker loads and another for 4-ohm loads.
Note: A perfect power amplifier can deliver double the power when the
loudspeaker impedance is halved. For example, a high-end power amplifier
can deliver "120 Watts into 8 ohms" or "240 Watts into 4
ohms". But few, if any, receivers can achieve this level of performance.
Harmonic Distortion (THD). This is a measure of how
"clean" a receiver can amplify audio signals. If you
enjoy music at louder volume levels, you will want to pay extra attention to
this part of a receiver's power specification. Since harmonic
distortion is a bad thing, lower numbers for THD are
better. Typical values are 0.05% to 0.08% THD for a
"clean" receiver, but any value below 0.1% THD is
acceptable. Don't compare THD values for receivers of different brands
too closely since there are some slight variations as to how this number is
measured across different manufacturers. Use it to compare receivers
with the same brand, but across brands only a difference of 0.03% THD or
greater should be
If you want a
good home theater experience and your budget is flexible enough,
recommend choosing a receiver with a power specification that
reads something like "80 Watts RMS into 8 ohms per channel,
20 Hz to 20 kHz, all channels driven
with no more than 0.08% THD".
This kind of
specification will ensure that your loudspeakers are getting the power
they need to reproduce demanding movie soundtracks and music with the highest
possible fidelity. (We'll talk about how much power you really need in the next
Compared to the two-channel stereo receivers of
a decade ago, today's home theater receivers have at least five channels of
amplification. While the digital components of a receiver have
significantly increased in computational power at the same time as getting much cheaper, the power amplification
components have not benefited from an equal drop in price. Consequently,
to make home theater receivers affordable and price competitive with the
two-channel stereo receivers of yesteryear, manufacturers have started to use innovative
technologies as well as "cut corners" to meet specific price points.
To meet certain consumer-friendly price points, equipment manufacturers are
practicing what is called specsmanship. This is a practice where
manufacturers dress up or cover certain performance specifications in a manner
where a casual, ill-informed consumer is likely to miss out on the
not-so-subtle differences. The three parts of the power amplification subject to specsmanship are: continuous
(RMS) power, frequency range, and channels
driven simultaneously. Instead of specifying continuous or RMS
power, manufacturers use peak power in the specification for their entry-level
receivers. Instead of specifying power over the full range of audible
frequencies, manufacturers specify the power for only one frequency (usually
1,000 Hz or 1 kHz). And instead of specifying power as "all channels
driven simultaneously", manufacturers simply say nothing. So a power
specification with specsmanship reads something like: "100 Watts peak
@ 1,000 Hz, 0.10% THD". In our opinion, the two most onerous
practices in specsmanship are in the continuous (RMS)
power and frequency range part of the power
specification. It is to our disappointment that the FTC (Federal Trade
Commission) has allowed such specsmanship practices for peak power and
power specification for a single frequency, without making a concerted effort
to educate the consumer. There's nothing wrong with
buying an entry-level receiver from a manufacturer who uses this type of
specsmanship, so long as you (the consumer) are aware of the not-so-subtle differences. Many
receivers under $600 are subject to specsmanship, but those that cost more are
not necessarily exempt. And
now that you're informed, you can intelligently compare receivers
apples-to-apples and know what you're getting.
Much Amplifier Power Do I Need?
you know how amplification power is rated, the next step is determining how
much power you will need. Surely, more power is better, but most of us
live with fixed budgets, so practically speaking, we need to know how much is
enough. The amount of power you need will depend on a number of
factors. The most important factors are your loudspeaker's sensitivity,
size of your room, and how much headroom
you want in your system.
Sensitivity. A loudspeaker's sensitivity is a measure of how
much sound the loudspeaker puts out for a given amount of power input from a
receiver. Usually, it is expressed in terms of decibels (dB) sound
pressure level (SPL) per 1 Watt of amplifier power measured at 1 meter from
the speaker. Different loudspeaker designs will have different
sensitivities. Most loudspeakers have sensitivities in the range of 85 to
91 dB SPL/1W/1m. Frequently, it is understood that sensitivity is
measure with 1 Watt of power input at 1 meter, so sensitivity is usually expressed
as just "dB". The higher the number, the more sensitive or the louder the
sound output from a loudspeaker given the same power input. Since
sensitivity is measured in decibels, a 3 dB difference in sensitivity means a
doubling or halving of amplification power to achieve the same loudness (SPL).
In other words, a loudspeaker with a sensitivity of 87 dB requires twice
the amplification power of a loudspeaker with a sensitivity of 90 dB. A
power amplifier delivering 100 Watts of power into the 87 dB loudspeaker
produces the same loudness as a power amplifier delivering 50 Watts of power
into the 90 dB loudspeaker. This is why loudspeaker sensitivity is an
important consideration when determining the power required from a receiver.
Note: For an 8-ohm loudspeaker, power input of 1 Watt corresponds to 2.83
Volts. But some loudspeaker manufacturers specify their 4-ohm
loudspeaker's sensitivity with a 2.83 Volt signal, which corresponds to 2
Watts of amplification power. This gives a false impression that their
4-ohm loudspeaker is more sensitive than it really is.
Size of Your
Room. Larger rooms will require more amplification. As a
rule of thumb, use the following table to determine the power amplification of
your receiver. This table assumes that you want your home theater system
to be able to play at movie theater reference volume levels. First, look up your speaker's sensitivity in the first
column, then find the size of your home theater room as measured in cubic feet
in columns 2-4. Compute the room size by multiplying the width and
length and height of your room in feet. Then look up the value of the minimum
suggested amplification power (expressed in Watts per channel).
(Example: A loudspeaker with a sensitivity of 88 dB in a room that is 2,500
cu. ft. should be driven by a receiver with at least 64 Watts per channel.)
for Minimum Receiver Power Amplification
(minimum recommended power, in Watts per channel)
(less than 2,000 cu. ft.)
(between 2,000 and 3,000 cu. ft.)
(larger than 3,000 cu. ft.)
Note 1: This table is based on the Home THX Program's recommendation of
achieving a peak sound pressure level (SPL) of 105 dB, which can be
achieved with 64 Watts into a loudspeaker sensitivity of 88 dB. Typical
listening levels are usually in the range of 80 to 90 dB SPL.
Note 2: If your array of loudspeakers vary in terms of
sensitivity, use the lowest sensitivity number from the front, center, or
right loudspeakers. The sensitivity of the surround sound loudspeakers
are secondary when it comes to figuring the minimum power amplification.
Headroom. Keep in mind that
the table above indicates the minimum amplification power you'll need. Usually, you will want more power in case you move your home
theater to a larger room or simply to have what is called headroom. Headroom
is the power reserve that is above and beyond what you normally need in
steady-state that allows your system to respond to very brief loud
passages. This is particularly important if you're a big fan of action
movies with lots of explosions. So yes, buy the most powerful receiver you can
afford, but keep in mind how amplifier power ratings are specified.
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