Saturday, February 14, 2009

RT Article: Connections. What's What

Connections, what's what. Home Entertainment

This is a little guide to figuring out what connection goes to what, and what to use, etc...

In today's world of Home Theater systems, there are a gazillion different types of connectors, each with a unique purpose and design, and for some of us... it's hard to keep them all straight. That's why I wrote this little guide to decipher which is which.


RCA connectors
These are by far the most common standard for audio interconnects. They are all analog, and usually stereo (left is white, red is right), although some early DVD players and receivers had 5.1 RCA connections (using six cables). You might also run into a mono audio connection, which can be plugged into stereo inputs via a y adapter cable.
Most RCA connectors are "line level," a standard output voltage, meaning that if you plug a CD player into the CD input, it work just as well as if you plugged it into the Tape or Aux input
There are two exceptions to this. The first are turntables. The output of a phono cartridge is much weaker than line level, and is also equalized differently. For this reason, you should only plug the phonograph into the phono input. If your stereo does not have phono preamp, you can buy a small, external amp. The second are speaker connections. Back in the 70s and 80s, it was common to use RCA connectors for the speaker outputs. These should NEVER be plugged into line level jacks.

Coaxial and Optical Digital Audio (Sony/Phillips Digital Interface or S/PDIF. pronounced "spid-iff")
The digital audio connections are found on most modern equipment, such as DVD player, satellite/cable boxes and game consoles. S/PDIF can do anything from CD audio, to the latest high definition surround sound formats found on Blu-Ray discs. Definitely use S/PDIF over analog RCA if the option is available.

Video connectors

Video connections are definitely more complicated than Analog. However, once you understand the differences, choosing the right cable is fairly simple.

RF Modulated Video (Coax). These were the first type of connectors found such devices as VCRs, and for good reason. Most TVs in the 70s and 80s didn't have a direct video input. Instead, they had a tuner to tune in different channels. When VCRs and other video source components were introduced, they used RF modulators to put the video on a channel (3 or 4). The TV viewed it just like any other TV channel. Most of the time, RF modulated outputs only have mono audio and a less than optimal picture. Use RF Modulated ONLY if you have to.

Composite Video (Coax with an RCA end, yellow). Composite video is identical to RF modulated, except for the fact that it isn't modulated to a channel. This yields a noticeably sharper picture, and reduces the electronics (and distortion) in the signal path. As an additional benefit, most Composite connections use stereo audio, too.

S-Video (a mini-din connector). This is a step up from Composite and is often found on laptop computers. S-Video is usually the best connector on older gear. S-Video separates the Chrominance and Luminance signals for an even sharper picture.

Component Video (Three coax cables with RCA ends, usually Red Green and Blue). The best analog video connector there is. Component separates the Red Green and Blue for an exceptional picture. Component supports Standard Definition (480i) as well as High Definition (480p, 720p and 1080i) resolutions.

Digital Video Interface (DVI. Usually a white connector with a large number of pins). This digital video connector (primarily found on computer monitors) is found on older High Def equipment. It is forwards compatible with High Definition Multimedia Interface (HDMI), and adapter cables are easy to find.

High Definition Multimedia Interface (HDMI). This cable, a little bigger than a USB cable, can carry both digital video and digital audio, and is currently (and for the foreseeable future) the industry standard for connecting HD sources. Use it whenever you can.

Don't get ripped off by cables.

Many people think they need to buy some super fancy Monster Cable to get the most out of their audio/video gear. This is simply un-true. Monster Cable and other high priced cables like it are simply a waste of money and should simply be avoided. Here's a quick guide to finding good cables at affordable prices.

Composite Video, Component Video and Coaxial digital audio connectors all use standard coaxial cable and RCA ends. At the distances found in most home setups (usually 12ft or less), there is no discernible difference between cables. If you need custom lengths, they are very easy to make (all you need is coax cable, RCA connectors and soldering equipment.)

RCA and S-Video cables use twisted pairs of wire with a little shielding around the edges. Get the cheapest stuff available. These are also practical to make custom lengths if needed.

DVI and HDMI. These cables use shielding around a number of twisted pairs of wires. Because of the complex connectors, it's impractical to make these cables. Since these are all digital, practically, they either work or they don't, so don't bother with the fancy stuff.

Optical digital audio. While it might sound really fancy, optical digital connectors are just a small piece of fiber with plastic ends. Since there is no electrical connection, there's no need for gold plated ends or what not.

Speaker cable. Don't ever buy stuff off a spool, especially if it has a name brand. Your probably paying 50% or more markup. Instead, measure how much you need (add a few feet to that), then run out to your local Home Depot and get good ol' #14 zip cord (if your feeling extreme, get #12). No need for fancy gold plated ends, either. Whip out (or borrow your neighbor's) soldering gun, grab a roll of solder and tin the ends your self.

Good places to buy cables. In general, I'd HIGHLY recommend you never buy cables at Best Buy or other big box electronics stores, or for that matter, most other local retail outlets. Why? Because they sell name brands (like Monster Cable) at a lage markup. If you must get a cable locally, go to Wal-Mart or other discount store and get the cheapest one you can find. Phillips/Magnavox makes a pretty complete line of cables, which are fairly affordable. Also, zip cord at most hardware, home improvement and electrical stores is fairly affordable.

There are a couple online stores that offer really good selection and prices. offers a large selection and rock bottom prices. In addition to home theater cables, they also offer computer cables, etc... The site is widely respected and a favorite among Home Theater enthusiasts.

Cable losses: taking the mystery out of amplifiers and cables.
On a semi-related note, I'd like to tackle the subject of TV cable loss and how to properly design the TV distribution system in your house. Coax cable has a certain amount of loss (attenuation of signal). This is usually measured in db per 100ft. The better the cable, the less loss. There are three basic types of coax: RG-59, RG-6 (and RG-6 dual and quad shield) and RG-11. RG-59 having the highest loss and RG-11 having the lowest loss. Most houses are wired with RG-59 or RG-6. RG-11 is mostly used in cable TV or more industrial applications, where low loss over long distances is needed. In addition, there are few other things in a system that can decrease the signal. Wall plates (barrel splices) usually have a .5db loss. Two way splitters have 3.5db loss, etc... (see side panel). Using this information, it pretty easy to draw a diagram of your house's system, and with a few rough measurements, you can figure out approximately how much loss the system has.

Now, what do you do about the loss. Simple. First, optimize your system. For example, if you have a four-way splitter, but your only using two outputs, get a two way splitter instead. Also, make sure you don't have large coils of cable laying around (just cut off the extra). Next, Install an amplifier to compensate for loss (if necessary).

With cable TV, your provider is usually pumping more than enough signal into your house to compensate for a small setup. Unless your analog picture is fuzzy, digital picture freezes, or your internet is intermittent, I would leave it alone. If you have digital cable or cable internet, make sure to get a two-way amplifier (normal amps won't pass the signal coming from your modem or cable box). A quality amplifier is also key here. I'd recommend buying a quality unit from a place like, rather than the one at Wal-Mart.

With an over the air antenna, especially fringe setup, compensating for loss is critical. If you live more than 30 miles from available stations, a quality mast mounted pre-amplifier is a must. For areas with high signal levels (less than 20 miles), a Winegard HDP-269 is ideal (this unit has 12db of gain on both VHF and UHF and is designed for high-input levels). Out on the fringe, a dual input Channel Master 7777 pre-amp (with 23db on VHF and 26db on UHF) is a good solution.

With Satellite TV, you shouldn't need to do anything unless the cables are extremely long. In which case, a satellite inline amplifier should be used.

If you need help or have questions, I recommend asking on

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