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Q.
Audio and Video Cables: Does Quality Matter?
Whether you're a hardcore gearhead or you just bought your
first home theater system, you want to get the most out of
your audio/video equipment. Poorly made cables can allow noise
and interference to compromise the signals coming from your
source components, resulting in a subpar listening or viewing
experience.
If you owned a high-performance sports
car, you wouldn't outfit it with low-end tires — you'd get
insufficient traction, poor handling, and increased road noise.
You'd lose all the benefits of buying a high-performance car
in the first place. In the same way, low-quality cables can
rob you of the performance you paid for when you bought your
system.
Many A/V components don't include
all the cables you need; some may include a cable whose length
isn't right for your setup. And, when cables are included,
they're always low-quality. Replace those free "in-the-box"
cables with higher-quality ones, and enjoy more realistic
sound and a clearer picture.
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Anatomy
of a cable
There are three main parts of a cable which affect signal
quality: the conductor, the shielding, and the connector.
The conductor is the part of the cable through which the signal
actually passes. Since the conductor is basically a wire which
can act as an antenna to receive radio frequency interference
(RFI) and electromagnetic interference (EMI), a good cable
also includes some kind of shielding, to
filter out these potential sources of noise. The connector
is the part of the cable that actually comes into
contact with your gear; types of connectors include RCA, S-video,
and F-type.
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Audio
interconnects
Most good audio cables contain an oxygen-free copper (OFC)
conductor, which passes signals accurately with minimal signal
loss. Many cables also include two separate shields — one
made of braided copper, to guard against RFI, and one made
of foil, to guard against EMI — so that no annoying buzzes
or "pops" are introduced into the signal.
In many cables, the shield is grounded
only on the end that connects to the audio or video source,
so that interference will drain away from the destination
end of the cable. Cables of this type often have directional
arrows printed on their jackets, and should be hooked up with
the arrow pointing away from the source.
Connectors are extremely important
to cable quality. Good RCA connectors provide constant, high-pressure
contact with your components' jacks, and are usually gold-plated
to prevent corrosion. This results in high-quality signal
transfer that won't cut out intermittently or degrade over
time.
Some manufacturers offer several different
levels of cable quality; how do you pick the level that's
right for your system? If you've noticed lots of interference
in your picture or sound, or if you're running cable over
a relatively long distance, look for the best shielding you
can afford. (However, if you find you need an audio interconnect
longer than 30 feet, you'll get better results by running
longer speaker cable instead, and moving your components closer
to one another.)
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Digital
audio interconnects
A special subset of audio interconnects is digital audio cables.
There are two types: optical and coaxial.
Optical cables transmit digital audio
signals as pulses of light. Toslink connectors — the connector
type found on most optical cables — are often found on CD
and DVD players, as well as home theater receivers. Some portable
players (such as most MiniDisc and some CD portables) are
equipped with mini-optical jacks. To connect a standard-sized
component to a portable's mini-optical input (for recording
to MiniDisc, for example), you'll need a special Toslink-to-mini-optical
cable. To connect a CD portable's mini-optical output to an
MD portable's mini-optical input, you'll need an optical cable
with mini connectors on both ends.
Because they use pulses of light rather
than electrical impulses to transmit audio signals, optical
cables are virtually impervious to interference. It's still
important to look for a well-made cable, however: a quality
fiber-optic element can prevent jitter, while solidly built
connectors add durability.
Coaxial digital cables look on the
surface like standard analog RCA cables; however, you should
avoid using a standard audio interconnect to transfer a coaxial
digital signal. Cables engineered specifically to pass a digital
signal provide 75-ohm impedance and wider frequency bandwidth,
ensuring superior signal transfer.
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Common
video interconnects
Video signals can travel over many different types of cabling,
but the majority of video components are equipped with at
least one of the following four types of jacks (listed in
order from lowest-quality signal transfer to highest):
- coaxial RF, also known as F-type
- composite video, also known as
RCA
- S-video
- component video
Used for connecting antennas, cable
boxes, VCRs, TVs and more, coaxial RF cable (not to be confused
with coaxial digital audio cable, above) can carry video and
stereo audio information simultaneously. Standard coaxial
cable is stamped "RG-59"; higher-quality "RG-6"
cable features lower signal loss and better shielding, both
of which are essential for DBS satellite systems and longer
cable runs.
Composite cables plug into the composite
video jacks found on many kinds of A/V components, including
DVD players, VCRs, receivers, and DBS satellite systems. These
jacks are often marked in yellow, and grouped with corresponding
red and white stereo audio jacks. Composite video cables use
standard RCA-type connectors, and are designed for high-quality
video signal transfer.
S-video cables feature round, 4-pin
connectors, and transmit the chrominance (color) and luminance
(brightness) portions of a video signal along different paths.
As a result, they provide better color accuracy and detail
than either RF or composite connections do.
Found on most DVD players and HDTV
tuners, and on a growing number of TVs and A/V receivers,
component video connections deliver better detail and color
accuracy than you get with RF, composite, or S-video. They
do this by splitting the video signal into three parts, with
each part transmitted via its own cable. Unlike the other
three types of connections, component video is capable of
passing high-definition and progressive-scan video signals.
Because of their higher frequencies,
video signals are more susceptible to degradation than audio
signals are, particularly while traveling through a substandard
conductor. And, as with audio, radio frequency and electromagnetic
interference can taint the signal. This can cause lines, snow,
and other artifacts to appear on your TV screen. A higher-quality
cable with a copper conductor, 75-ohm impedance, and double
shielding can effectively preserve the strength and accuracy
of the original signal.
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Digital
video interconnects
The shift to digital video sources and displays has led to
digital video connections. There are two main digital video
options: DVI cables and HDMI cables.
DVI (Digital Visual Interface) and
HDMI (High-Definition Multimedia Interface) cables are especially
beneficial if you're using a "fixed-pixel" display
(like a plasma, LCD, DLP, or LCoS TV). Since these cables
permit the video signal to remain in digital form all the
way to the screen, you avoid the slight picture degradation
that can come with translating the signal from digital to
analog, and back.
Both DVI and HDMI cables can carry
standard-definition and high-definition digital video signals.
HDMI is also capable of carrying 2 to 8 discrete channels
of digital audio, depending on the capabilities of the source
component.
Most HDTV tuners and HD-ready TVs, and, increasingly, many
DVD players now come with either a DVI or HDMI terminal; a
few high-end components have both. Also, HDMI cables are backwards-compatible
with most DVI connections, so you can use an HDMI-to-DVI adapter
to connect a component with a DVI terminal to one with an
HDMI terminal.
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Specialty
cables
Game systems have come a long way in the last few years. Take
advantage of the high-quality picture and sound produced by
your PlayStation2 or XBOX™ console by using premium game cables
to connect it to your home theater system. Your gaming experience
will be much more intense, with clearer graphics and more
realistic sound effects.
If you've already got a digital camcorder
or you're thinking about buying one, you'll want to check
out our selection of i.LINK™ cables. Since camcorders rarely
include them, you'll need one if you want to hook your cam
to your computer's i.LINK jack in order to perform desktop
editing.
Because a high-definition video signal
contains so much more information than a standard-def signal,
only a few types of cables are capable of carrying HD. One
such type is i.LINK. Another, DVI, was designed specifically
for this purpose. Yet another type of cable, RGB, is often
used to connect PCs to monitors. Any of these connections
will give you superb image quality from your high-definition
source if you use a high-quality interconnect.
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Cable
connection tips
Follow these general rules of thumb to get the best results
from your cables:
- Avoid long cable runs
if possible — the shorter the cable, the better.
- That said, make sure your
cables are long enough, especially if your components
are shelved in such a way that the rear panels are difficult
to access. There should be enough slack to let you pull
the component forward and reach the rear panel.
- Because they can introduce interference
into the signal, try to keep power cords away from
signal cords. If this isn't possible, at least
try to minimize contact between the two.
- If an interconnect has arrows printed
on its jacket, hook it up so that the arrow is pointing
away from the signal source, and toward the destination.
- Avoid kinking or bending
cable. Don't try to make a short cable reach —
it can put stress on the connector and potentially cause
damage. Buy a longer cable, if necessary. (This is especially
important for optical interconnects.)
- Don't keep excess cable
lying in loops. Arrange it in an "S"
shape or a figure-eight instead; this can help minimize
electromagnetic interference.
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