A/V Receiver Buying Guide

The essential guide for mid-priced receivers

article last updated on 6.5.2002 | page 1 | page 2 | printer-friendly 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 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 Surround Sound Formats Primer and THX Overview.

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 performs the following functions:

• Switching for all of your home theater system's audio and video components

• Surround sound decoding

• Signal processing for simulated soundfields and bass management

• Amplifies the audio signals to drive the loudspeakers and controls the playback volume

• Serves as an AM/FM radio tuner

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.

• 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.

For 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 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.

Audio Signal Processing

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.

Digital 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.

Simulated Soundfields

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.

Bass Management

The receiver's bass management function re-directs the bass frequencies from any channel to those loudspeakers that 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 channels.

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.

Amplification

You 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.

Number of Channels

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.

The new and emerging surround sound formats are the 6.1-channel extended 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 amplified.

Amplifier Power Ratings

There are a number of aspects to a receiver's power rating, all of which should be considered carefully:

Continuous (RMS) 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 of "Watts RMS" (root mean square) or "Watts continuous".  Do not give credence to or compare receivers based on power specifications that say "Watts peak".

Frequency 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.

Channels Driven 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.

Speaker Impedance. 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.

Editor's 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.

Total 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 considered noteworthy.

If you want a good home theater experience and your budget is flexible enough,
we strongly 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 simultaneously,
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 section.)

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.

Specsmanship. 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.

How Much Amplifier Power Do I Need?

Now that 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, the size of your room, and how much headroom you want in your system.

Loudspeaker 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.

Editor's 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.)

 
Guideline for Minimum Receiver Power Amplification
(minimum recommended power, in Watts per channel) (v1.0)

 
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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In This Buying Guide:

> Introduction

> What is a Receiver and What Does It Do?

> Surround Sound Decoding

> Audio Signal Processing

> Amplification

> Switching

> AM/FM Stereo Tuner

> User Interface

> Construction & Build Quality

> Comparing Receivers

> Auditioning Receivers

> Where to Buy & Find the Best Deals

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