The A/V Receiver: A
Field Guide
Although home theaters can be staggeringly complex systems
that utilize entire closets full of gear, most consumers are interested in keeping things
simple. Most of us have space -- or cost -- constraints that make no-holds-barred systems
out of the question. One of the best ways to keep things simple is to use an audio/video
(A/V) receiver.
In a two-channel audio system, a receiver performs the
functions of three separate components: a radio tuner, a preamplifier, and a power
amplifier. In other words, it allows you to use the radio, switch sources (such as
cassettes and CDs), adjust the volume, and drive the speakers -- all with a single
component.
An A/V receiver is even more complicated. In addition to
allowing you to switch audio sources, most A/V receivers allow you to switch video
sources as well. You can take the signals from your cable box, VCR, DVD player, and game
console and choose which device is displayed on your television.
A/V receivers also decode or process the
encoded surround sound from television broadcasts, DVDs, laserdiscs, and videocassettes.
(See "Surround Sound Made Easy" for a further
explanation.)
Many A/V receivers also employ Digital Signal Processing
(DSP), which synthesizes surround sound from regular two-channel source material. DSP
usually has several settings, labeled with names such as "Hall,"
"Stadium," "Church," and "Club." There's a drawback,
however. The programs used to simulate surround sound are not subtle and the effects seem
exaggerated and overwhelming. Once the novelty value has worn off, most consumers simply
ignore the DSP functions.
However, don't write off DSP just because the synthesized
surround included on most receivers isn't impressive. DSP is actually a powerful tool
which will play an increasingly large role in audio as engineers get better and better at
manipulating digital signals. It offers tremendous potential in the realms of room and
speaker equalization.
A/V receivers differ from their stereo counterpoints in one
other obvious way -- a stereo receiver supplies two channels of amplification while an A/V
receiver usually supplies five (or sometimes seven) channels.
Now that you understand what an A/V receiver does, how do
you decide which one you need?
One from column A, one from column B . . .
First, you need to do an inventory of what you want from a
receiver. One huge difference among A/V receivers is the amount of power they can supply.
If you have a large room or if you have insensitive loudspeakers, you'll need more power;
if you have a small room or use speakers with high sensitivity, you won't need as much
power.
There's a catch, of course. Power costs money, to put it
simply. Inexpensive receivers tend to be low-powered receivers, but sometimes, in an
effort to keep prices down, manufacturers will supply two or three channels with
substantial power outputs, combined with two low-powered channels.
In the days before discrete digital surround systems, such
as Dolby Digital and DTS, this was far more common -- and in fact, it even made a certain
amount of sense, since the surround channels merely carried effects. But discrete digital
surround schemes send full-range signals, and contemporary systems employ larger speakers
as surrounds, so high-quality manufacturers increasingly build A/V receivers with equal
power in all five (or seven) channels.
In addition to checking the power output of a receiver,
check its speaker connections. The least expensive receivers use a spring clip, which will
only accept thin, bare wires (or pin connectors). Better receivers offer more substantial
connectors, ranging from various types of binding posts to the BFA connector increasingly
popular in Europe.
Another expensive option is video switching. There are
three different connection schemes for video equipment. The most common is called composite
-- the signal is carried by a single wire and uses an RCA connector just like the cables
that carry the musical signal. A higher-quality connection -- usually -- uses a special
DIN-style connector and is called S-video. S-video separates the color
(chrominance) signal from the brightness (luminance) signal. Component video
separates the signal into three elements (and requires three inputs). Component video
further splits the signal, separating the color information into two color-difference
signals, while still keeping the luminance signal separate from them. By splitting the
picture signal this way, component connections pass along an unfiltered image with
superior resolution and tremendously improved color saturation.
Inexpensive A/V receivers may only feature a few composite
video inputs. As you go up in price and quality, you will find S-video and, with the best
and most expensive receivers, multiple component inputs and at least one component output.
Always make sure the receiver you buy has at least a sufficient number of the inputs you
already require -- but it's never a bad idea to allow for future expansion.
The real heart of your A/V receiver is its surround-sound
processor. You can buy entry-level receivers which only offer Dolby Pro Logic processing,
but they're becoming rare. Most receivers these days offer at least Dolby Digital
decoding. More expensive models may also offer DTS or even Dolby Surround EX or DTS ES.
(See "Surround Sound Made Easy" for more detail on
these surround-sound formats.)
Most contemporary A/V receivers offer digital inputs as
well as multiple analog inputs and outputs. Which should you use? It all depends.
If your A/V receiver is your newest component, its internal
digital processing may be better than that of your CD or DVD player. If this is true, you
should use the receiver's digital inputs, so you can use its digital-to-analog converter.
If your DVD player is your newest component and it features
six-channel analog output, you may prefer to use its analog outputs so you can take
advantage of its superior internal surround-sound processing and digital-to-analog
conversion.
And in the end …
One final caveat. It may sound as though all it takes to
successfully buy an A/V receiver is to shop for the options you need and then find a model
within your price range. It is important to make sure your A/V receiver offers the
performance and convenience features you require. And fortunately most A/V receivers offer
a lot of convenience and performance, no matter what price range you are shopping in. But
never forget that none of that means much if you don't enjoy listening to music or
watching movies with your receiver. Your eyes and ears should always be the final arbiter
when you buy an audio/video component.
Take some of your favorite music to the store with you and
listen to it before making your final decision. You might also want to take a DVD with
you. Don't worry about taking a sonic spectacular with you -- most stores will have The
Fifth Element or Star Wars Episode One: The Phantom Menace or Apollo 13
lying around. Take a disc you know well, preferably one with a fairly subtle effect, and
listen to it in addition to the louder, more obvious choices.
If your new receiver sounds good and offers all the
features you require, you'll enjoy using it and you will use it. And that's what
it’s all about.
...Wes Phillips
wes@onhometheater.com
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