How do I know which cables to use?

The cable selection at the electronics store could be renamed the "wall of confusion." Not only are there dozens of different kinds of audio/video cable -- some for stereos, some for home theaters, some for HDTVs and some for … who the heck knows? Even if you're lucky enough to find the cable you need, you still have to decide between super expensive and suspiciously cheap.

And then there's the salesman. "Have you heard of silver-plated connectors?" What? "If you're buying speaker wire, then you should also buy these stands that keep the wire from touching the floor." Why? "The more expensive the cable, the better the sound." Really?

In this article, we're going to give it to you straight. We'll explain, in simple terms, what each type of audio/video cable does and where it should be used. Along the way, we'll debunk some cable myths, starting with the idea that the most expensive cable is the best.

Gold-plated cable connectors are supposed to make your music sound better. But is it true?

© iStockphoto/alptraum

What is cable?

The role of cable is to carry an audio or video signal from one device to another. Cables carry signals between DVD players and TVs, stereo receivers and speakers, and computers and video projectors. Cables don't change the nature of the audio or video signal they carry. They don't convert or process signals in any way. That's the job of the devices on either end. The cable itself is just the messenger.

Cables are made up of three basic parts: conductor, shielding and connector. The conductoris the wire that actually carries the signal. One or more layers of shielding prevent the wire from acting as an antenna that picks up radio frequency interference (RFI) and electromagnetic interference (EMI). The connector is the plug at the end of the cable that connects to your device.

Cables are important components of any home stereo or home theater setup. If you don't use the right cables for the right job then you could end up with subpar sound or picture quality. And if you use cables that are damaged or otherwise junky, you could really end up with a lousy experience. For audiophiles, using low-end cables with a $5,000 plasma HDTV is like putting crappy tires on a Ferrari.­

Some audio/video experts argue that consumers should spend 20 percent of their total system cost on cables alone. The truth is that many cheaper cables offer a listening/viewing experience that most consumers could never tell from the really high-end cables.

To keep things simple, we're going to break down the overwhelming amount of cable types into three categories: audio-only, video-only and audio/video cables that carry both sound and picture.

Audio Cables

Let's start with audio-only cables. The most common audio cables are called analog RCA cables. These are the cables with red and white, or sometimes red and black connectors. RCA cables are widely used to connect devices like VCRs and DVD players to TV sets or CD players to stereo receivers. RCA audio cables come in pairs with two connectors on each end, a red one for right stereo and a white (or black) connector for left stereo. They are often bundled with video cables. Experts recommend gold-plated RCA connectors for extra protection against corrosion, especially if you live in a humid environment.

The other most common type of audio cable is speaker wire. Speaker wire runs from a stereo receiver to all speakers except the subwoofer (that requires a coaxial cable). Each speaker needs its own dedicated wire. Speakers not only receive audio signals via speaker wire, but also power.

Speaker wire is made from 99 percent oxygen-free copper and usually comes "unshielded," which means you can see the copper conductor. Speaker wire comes in different thicknesses or gauges rated from 12 to 18 (thickest to thinnest). As a general rule, the longer your speaker wire, the thicker the gauge you should use. For speaker wire lengths up to 20 feet (6.1 meters) long, 14-gauge is sufficient, but anything longer than 60 feet (18.3 meters) requires 12-gauge wire.

Speaker wire is fairly simple, so you can get away with buying inexpensive, bulk wire. And don't let anyone tell you that all of the speaker wires in your system need to be the same length. That's a myth.

Most audio recordings are digital nowadays, and there are several newer cables that specialize in carrying high-bandwidth digital audio signals. Optical digital cable(also known as fiber-optic and Toslink) transmits audio signals as pulses of light and is impervious to interference. Another digital audio cable is called digital coaxial. It looks the old coaxial cables that connect satellite dishes or cable TV signals to televisions, except this is specially designed to carry digital audio. You'll find optical and digital coaxial jacks on newer DVD players, CD players and stereo receivers.

The last type of audio-only cable is called analog multi-channel cable. This cable is designed for use with special players such as DVD-audio that play discs recorded at high sample rates for the maximum sound quality. Analog multi-channel cable consists of six to eight bundled RCA connectors, each responsible for a different audio channel on the back of a stereo receiver.