HomeTheater 101: Cables

Posted in FAQs & Guides,Home Theater by Michael Pica on the May 17th, 2007

In part one I discussed the Display; how to pick a technology based on your room situation, how to choose a size and resolutions, and different things to look and look out for. In part two I discussed Surround Sound; why you should avoid home theater in a box systems and how to shop and choose the best system for you. That and some media is pretty much all there is to building a home theater right? WRONG. What was originally going to be my final chapter on the subject I decided to dedicate entirely to cables, there is just too much to cover it’s deserving of it’s own article. So: Do you know what ELSE goes into building an awesome home theater experience?

The value of a cable
When I talk to people about cables for their home theater there seems to be two schools of thought. One will just go out of their way to buy the cheapest cables possible figuring that wire is wire is wire so: why waste money? The other is the complete opposite, figuring that they should spare no expense when it comes to cables and end up paying $150 for a 3ft HDMI cable. Both schools are right and both schools are wrong at the same time.

For the most part wire is really just wire, while their might be some disparity in the quality when comparing the really low end stuff to anything of reasonable quality there really isn’t all that much difference across the board. Really when you pay for cables you’re paying for overall build quality and packaging. There are however a few things to look for when buying cables and wires.

Connecting the dots, understanding what makes a good cable.
The diameter of a wire is measured in “gauges” the smaller the gauge the larger the wire is. a 20 gauge wire is significantly smaller then a 16 gauge wire. In general larger gauges (those with a smaller number) are better. Larger wire is capable of holding a stronger signal, which is important when dealing with long distances, like extremely long cables running to a projector, or higher power situations, like speaker wire. since gauge is such an important factor, if the cable doesn’t tell you the gauge wire it uses don’t buy it, it’s that simple. It’s always a good rule to not buy things unless you know exactly what it is you’re getting.

In addition to paying attention to diameter another important factor is shielding. Shielding is a mesh of grounding wire that surrounds the signal wires. This is important because it helps to reduce noise and interference in the data caused by other wires and other devices. Some cables made for high noise environments might be shielded as many as four times. Shielding is most important for cables with low level signals such as pre-amp and video cables as well as cables traveling long distances. It’s rarely used on speaker wire because that signal is amplified and rarely effected by outside interference.

Another important factor when dealing with cables is impedance; this is essentially a value that measures how much of a signal’s strength will be diminished by the wire itself. All wire has some amount of impedance and less is not always better. Basically there are standards for how much impedance should be present in a particular cable, essentially the electronics at both ends of the cable are designed to work with a certain amount of impedance in the cable. I wont get into the technical details; though, if you’re interested Blue Jeans Cable has a good wright up on the subject. Most applications call for 75ohms but some applications are designed for other levels, do your research before you buy.

Speaker wire is a little different as you typically cut the length yourself and it’s impedance can vary by length. For speakers it’s a good idea to use the same brand model and size for all your speakers and the same length of wire from your receiver to each speaker. if you want to save a bit of wire or wire clutter you can get away with at least using one length for all the front speakers and another length for all of the rear speakers. Aside from keeping speaker wire the same length you generally want to keep all your wires and cables as short as possible. Shorter wires translate to stronger signals, less interference, and of course less wire clutter.

Material is the last important factor though this one is pretty easy. you’ll see “oxygen free” advertised a bit, this basically means that the wire used is free from defects to help ensure a clean signal. Copper and copper alloys are usually considered the best for transmitting the actual data and should be used in the wire itself. For connectors Gold plating is a good idea (it’s usually plated over nickel or some nickel alloy). The reason for that is Gold is very resilient to oxidation and other surface conditions that would disrupt the signal at the point of connection. Also being one of the most malleable materials it tends to make a much more solid connection as it can deform slightly under the pressure of the connection. This malleability is also the reason you should look for gold plated connectors and not solid gold or gold alloy connectors, particularly where some connectors like HDMI or DVI use lots of very small pins the connector would be much more susceptible to damage.

Fiber optic cables like toslink connectors play by completely different rules than the cables above. They use plastic strands to transmit light. This means that they don’t require any shielding, the major factor in dealing with fiber optics is the build quality of the connector as a poor quality connector can make for a weak signal by not directing the light directly into or out of the cable. When running or handling fiber optic cables tight bends or kinks should be avoided at all costs, the more dramatic a bend the weaker the signal will get and if it gets too low your sound will cut out completely.

Choices and Formats
In many situations you’ll be faced with a few choices with the type of cable you can use. Lets say your DVD player gives you the option of Component video or HDMI which one should you go with? Some times this decision will be easy, other times it can be more difficult and require you to experiment, and sometimes you wont even have a choice.
Video cables essentially have a pecking order of quality, but beyond that we can categorize cables into even more generic categories: those that support high definition, and those that do not. Composite (single prong yellow RCA connector) and S-Video (circular 4 prong connector) are always only standard definition. Despite the common misconception that S-Video can support EDTV or HDTV signals it cannot. S-Video does offer a higher quality connection then composite but it doesn’t in any way shape or from transmit anything at a higher resolution.

High definition cables usually come in the form of component video (not to be confused with composite, check the last for letters) or HDMI, both of which are capable of SDTV (480i), EDTV (480p), and HDTV (720p,1080i/p) resolutions. VGA and DVI are interesting beasts for most purposes VGA is similar to component video but different enough that it’s really it’s own format and DVI is essentially a VGA cable wrapped up with an HDMI cable, both are designed for computer use but will be found in home theater equipment on occasion. VGA and DVI, since they’re designed for computer use, also have the luxury of carrying non-standard resolutions.

In general the video cable pecking order is as follows:
Composite < S-Video <<< Component < VGA < HDMI

This isn't always a hard fast rule though. In certain situations the better choice can depend on how your display interprets the signal from certain formats, so while theoretically s-video is better then composite, I've seen displays where composite looked better simply because the display didn't interpret the s-video signal well. This also happens quite frequently when going between component and VGA, often using a component cable will look better on a display that doesn't handle a VGA signal well. The difference across the top end is marginal at best, most people I've tested can't tell the difference between video over component or HDMI, hardcore detail oriented people could probably notice the minor differences under scrutiny but it's nothing so major as to go out of your way and spend hundreds more for an HDMI connection. Component is more then capable for a vast majority of high definition scenarios.

HDMI does have other benefits and given the choice with all other factors relatively equal I'd highly recommend going with HDMI. First lets mention digital rights management (DRM). Most HDMI (and some DVI) connectors support what's called HDCP. Since these connectors are digital they're able to encrypt the data going over the cable. While I personally despise this idea it doesn't change the fact that both Blu-Ray and HD-DVD will eventually start using this encryption. That means if you're not using both a cable and display that support HDCP you will not be able to view your movies in HD. Since Component and VGA are analog it's impossible for them to support HDCP. This isn't the case at present but it's something to keep in mind when attempting to future-proof your home theater.

Another benefit to HDMI is it's audio capabilities. HDMI contains not only a video stream but also an audio stream. The real benefit to using HDMI is the single cable solution. Think of just one AV cable from each device running into your receiver, then a single cable from the receiver out to your display, it's a really simplified setup and good for avoiding the typical "rats nest" scenario behind your equipment. The key is a receiver that supports HDMI, as that will be the device that buses the connection to all of your devices and without HDMI support in that device there's no real benefit in cable reduction. While a lot of today's devices don't support HDMI having a receiver that does will prepare you for when that day does come, and most of your other equipment supports it.

Even better then just supporting audio, is that HDMI supports new digital audio formats that other audio connectors do not. This makes it not only the most versatile video connector but the most versatile audio connector as well. It still loses out to a quality set of discrete analog audio connectors though.

Besides analog interconnects and HDMI most of the time you'll find yourself with the option of digital toslink (optical) or digital coax connectors. The idea behind optical connectors is that when dealing with light it's impossible for the cable to pick up interference and thus you'll have a cleaner signal. While that's true I'd recommend coax connectors for your digital audio if you have the option. Using a quality coax connection with proper impedance is a much more controlled environment and in my experience can offer, if not a higher quality signal, at very least more consistent performance. Over short distances with a properly shielded cable interference isn't that much of a problem anyway. Either way both of those connection types are far and wide superior to non-discrete analog connection (your red and white stereo RCA connectors) when dealing with surround sound.

In general the pecking order is as follows:
analog (non-discrete) <<< digital (toslink) < digital (coax) < digital (HDMI) << analog (discrete)

A Not on Adapters and Converters
A lot of people seem to think that if one type of  cable is better then the other that they should buy an adapter for that better quality cable. Let me be perfectly clear on this point. You should never use adapters or converts unless there is no other way to connect your two devices. The best connections are the ones with the least amount of modifications. If your display accepts HDMI and Component and your device only outputs component, then use component. There is nothing gained by converting the signal, it can only go downhill from the source and converting when you don’t have to only wastes money and has the potential for lower quality results.

These things should only be used if you have no other way to hook up one device to the next, and even then you should choose an adapter over a converter. An adapter will simply modify the shape of a connector to fit the device, it doesn’t do anything to the signal, a converter has circuitry that actually modifies the data to put it into a different format. Even if you don’t know how it works, anything that requires power or is contained in a box is definitely a converter; adapters are typically small lengths of wire or look like two connectors with nothing between them.

Buying the right cable at the right price.
So now that you know what to look for in a cable you might be worrying that I’ll suggest you go out and buy some ridiculously overpriced exaggerated strand of metal. Nope. Unlike speakers and displays there really isn’t much room for personal opinions and preferences when it comes to cables. A cables job is to transmit data from one place to another perfectly with nothing added or missing. How well a cable performs these tasks is actually pretty easy to do. Beyond that you’re looking at build quality to make sure the things don’t fall apart on you. Looks shouldn’t really matter as cables should be hidden out of site, if you’re buying based on looks you’re buying for all the wrong reasons.

Typically I try to stay unbias when dealing with brands and such but this is one instance where I’m going to just put my personal preferences out there in the open. Don’t buy Monster cables, and don’t buy cables priced as high as Monster cables. They’re a plain old rip-off, I don’t care what the sales-jerk at your local big box tells you, they’re not even that great of quality (go look up some test results online, if you can actually find any you’d be surprised). They’re priced 10 to 15 times higher then they should be and their build quality and customer service is down right horrid.

There are a number of other bands I would recommend over them but I’m partial to Monoprice. They’re cables are typically superior in every way to what you get with Monster or a similar brand, and they’re priced cheaper then cables only half their quality. The only catch is that you can only order them online through their website. There are better cables out there but typically only once you start getting into the ridiculous price ranges. There are other good choices in cables too: Blue Jeans Cable which I mentioned before makes good quality cable as well as others. I’m partial to Monoprice, and thats what I use for all of my cables and I’ve never been anything but completely satisfied with my purchases from them.

Final thoughts
Cables are one of those important factors that ether gets overlooked completely or lots of money gets put in all the wrong places. Selecting the wrong cable might not ruin your experience but selecting the right one can make it that much better and can make a reasonable difference when running long distances or working in areas with a lot of outside interference. Good cables will also last you years and years and you don’t need to break the bank to get good quality cables either. It’s one of the few areas where a little background knowledge can go a long way towards both improving your experience and saving you money.

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