Inexpensive Home Theater: Technology Primer

March 23rd, 2007

Potential home theater owners are quickly bombarded with a new set of terminology, an array of acronyms, and specifications and technological details that can be confusing and difficult to keep straight. As I mentioned in my Introduction article, learning home theater technologies can be a great boon to home theater owners.

This article provides a primer on the technologies involved in building your own inexpensive home theater.

LCD vs. DLP
The video source of choice for most home theaters is a projector. A projector is mounted behind a wall or on the ceiling and projects the image onto a screen or flat surface. Projectors use one of two main technologies, LCD and DLP. Again I won’t go too deep into arguing which is better, but be aware of the different technologies and the strengths and weaknesses of both. Projection systems in home theaters are becoming much more popular because of the recent price decreases in HD-ready projectors.

Aspect Ratio
The shape of the screen is often referred to as the aspect ratio. Old school TVs were in a 4:3 aspect ratio. Widescreen TVs are usually defined as 16:9 ratio. HDTV comes in a 16:9 ratio. When you buy a DVD they usually come in either full-screen (4:3) or widescreen (16:9) aspect ratios. If you’re putting in a home theater, you want to put in a screen in the 16:9 (widescreen) aspect ratio. Full screen is dead; widescreen is definitely the way to go.

Resolution and Progressive vs Interlaced
You will see 480p, 720p, 1080i, and 1080p when looking video specs. These curious numbers refer to the resolution of the image. These numbers are a type of shorthand measuring the number of vertical lines displayed in that image. The bigger the number, the more vertical lines displayed in the image, or to say in another way, the higher the resolution of the image.

The suffix of p or i represents progressive or interlaced. Without getting too technical, progressive means the lines are each drawn sequentially, but interlaced is the old-school way of transmitting video. Interlaced draws every other line of each frame, rotating odd and even lines. Even though it has been around for a while, it does have its place — even the video geeks can’t firmly decide which is better. But, I have my upscaling DVD player set at 720p and I like it.

Cable Types
Video signals are carried to the video source through cables. There are many different type of cables to carry the video signal including HDMI, component video, RCA, DVI, and S-video. Home theater owners should mainly be concerned with HDMI and component video, since these two provide the highest quality and can carry an HD signal.

Audio cables are also very important. In addition to the regular copper speaker wire, you will need S/PDIF cables to carry the digital audio signals between your AV receiver and components that provide your surround sound. Usually these come in optical (TOSLINK) or coax varieties, either of which is suitable to carry the signal required for surround sound.

Networking and power cables will also be crucial in many home theater setups. Knowing a little about Cat 5 and coax cables will go a long way in deciphering functionality and troubleshooting if things go wrong.

HDTV
A home theater using standard definition TV is a horrible waste. Watching HDTV on a home theater is a wonderful experience — the picture is sharp and clear, and the sound is coming through in 5.1 surround. With standard definition the picture looks extremely fuzzy since the larger sized screen magnifies the imperfections that are usually overlooked on a regular-sized TV. The sound from standard definition TV signal only uses the left and right channels. Once you get HD in a home theater and switch to the same TV program in standard definition, you’ll notice the huge difference in quality and be aware of the huge gap between HD and standard definition.

Surround Sound
Surround sound is pretty easy to figure out. There is usually a number associated with surround sound 5.1 being the most common, but you’ll also see 2.1, 2.0, 5.0, 6.0, 6.1, 7.0, and 7.1. The .1 or .0 denotes with our without a subwoofer, respectively. The whole number represents the number of speakers and the general speaker placement. 5.1 includes a front-center channel, a right front and a right left channel, a surround left and surround right channel, and a subwoofer. The sixth channel adds a center rear channel, while the 7 speaker configuration uses two rear speakers instead of just a rear center, one on the right and one on the left.

Again, this was meant to be a simple primer to get you started on your home theater knowledge, you’ll find you have to know more as you go further, but it should be a solid foundation for you to build on. Even a basic understanding these concepts will help you make better decisions as you plan your ultimate inexpensive home theater system.

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