Working of Home Theater

How Home Theater Works

Until recently, the best way to watch a movie was to go to a movie theater. The introduction of VCRs made it easy to rent or buy movies and watch them at home, but TVs just didn't compare to movie theaters' huge screens and surround-sound systems. Not only did TVs have comparatively tiny screens and lower quality speakers, formatting a movie to fit the screen got rid of a substantial part of the picture.

Now, more and more people are turning their ordinary TV rooms into home theaters. This used to involve a projector and a screen, and it was too expensive for most people to afford. But advances in technology have given people more choices for home theater setups, and some people find that a home theater is quieter and more convenient than a movie theater -- and the picture and sound are great.

If you're looking for a home theater system, you have a lot of decisions ahead of you. In this article, we'll go over all the components that make up a home theater system. You'll learn what each component does and what to keep in mind when you make your selection. If you're thinking of turning your den into a fully functioning home theater, this article will help you get started.

What Is Home Theater?

Home theater is difficult to define -- it's really just a vague term for a particular approach to home entertainment. Generally speaking, a home theater system is a combination of electronic components designed to recreate the experience of watching a movie in a theater. When you watch a movie on a home theater system, you are more immersed in the experience than when you watch one on an ordinary television.

To see how home theaters do this, let's take a look at the original model -- the movie theater. When it comes to picture and sound, the theater can offer an amazing experience we just don't get at home. That's usually why people will pay to go to the movies, even though renting a movie is cheaper. There are a few main components that make watching TV and going to the movies very different.

• One of the biggest differences is the sound experience. When you go to see a movie in a quality movie theater, you'll hear the music, sound effects and dialogue not just from the screen, but all around you. If you've read How Movie Sound Works, you know that a standard movie theater has three speakers behind the screen -- one to the right, one to the left and one in the center -- and several other speakers spread out in the rest of the theater.

  In this surrounding sound system, you hear different parts of the soundtrack coming from different places. When somebody on the left side of the screen says something, you hear it more from the left speaker. And in a movie like "Star Wars" you hear a rumbling swoosh travel from the front of the theater to the rear as a spaceship flies toward the camera and off the screen. You are more involved in the experience of watching a film because the world of the movie is all around you.

• The second chief component of the theater experience is the large size of the movie screen. In a theater, the screen takes up most of your field of view, which makes it very easy to lose yourself in the movie. After all, you're sitting in the dark with only one thing to look at, and everything you're looking at seems much bigger than life.

• We also enjoy going to the movies because we can see everything so well. Film projectors present very large, clear pictures. The detail is much sharper than what we see on an ordinary 19-inch television, and the movement is much more fluid. We may not consciously recognize this, but it does make a significant difference in how we enjoy a movie. When we can see more detail, we are more engrossed in the world of the movie.

The basic idea of a home theater is to recreate these elements with home equipment. In the next section, we'll look at an overview of what you need to get started.

What Do You Need?

In the last section, we saw that the major components of a movie-theater experience are a large, clear picture and a surround-sound system. To build a home theater, then, you need to recreate these elements. At the bare minimum, you need:

• A large-screen telivision (at least 27 inches across, measured diagonally) with a clear picture
• At least four speakers
• Equipment for splitting up the surrounding-sound signal and sending it to the speakers
• Something that plays or broadcasts movies in surround sound, preferably with a clear picture

And, of course, you'll need a room where you can arrange all this stuff.

There are any number of ways you can meet these criteria. In the end, your home theater system depends on how much money you're willing to spend and how important certain areas of performance are to you.

One home theater option is a "home theater in a box" system. This one from Sony consists of a DVD player with built-in surround-sound receiver and a collection of speakers.

If you're not looking to spend much money and already have a good-sized television and a stereo system, you can upgrade your entertainment system into a fairly crude home theater with a couple of extra speakers and a few other inexpensive components (see Accessing the Surrounding Channel to find out how). If you invest in a basic surround-sound system and a new DVD player, you might spend $500. For a more advanced system, with a larger television and an advanced sound system, you might spend about $8,000. For $30,000, you could set up a real theater, with a projection television, built-in speakers and bolted theater seats (and maybe a concession stand).

In the following sections, we'll look at the different options for televisions, surround-sound receivers, speakers and video sources. We'll find out the advantages and disadvantages of different types of equipment, as well as the price range and long-term benefits. We'll also look at some of the extra components you can add to put the finishing touches on your home theater system.

Surround Sound Basics

The main thing that sets a home theater apart from an ordinary television setup is the surround sound. For a proper surround-sound system, you need two to three speakers in front of you and two to three speakers to your sides or behind you. The audio signal is split into multiple channels so that different sound information comes out of the various speakers.

The most prominent sounds come out of the front speakers. When someone or something is making noise on the left side of the screen, you hear it more from a speaker to the left of the screen. When something is happening on the right, you hear it more from a speaker to the right of the screen.

The third speaker sits in the center, just under or above the screen. This center speaker is very important because it anchors the sound coming from the left and right speakers -- it plays all the dialogue and front sound effects so that they seem to be coming from the center of your television screen, rather than from the sides.

The speakers behind you fill in various sorts of background noise in the movie -- dogs barking, rushing water, the sound of a plane overhead. They also work with the speakers in front of you to give the sensation of movement -- a sound starts from the front and then moves behind you.

But how do all these sounds get split up? This is the job of the audio/video receiver, which is the real heart of a home theater. In the next section, we'll see what this component does.

The Receiver

The audio/video (a/v) receiver and amplifier assembly in a home theater does the same job as the receiver and amplifier assembly in any stereo system: It receives signals from various input devices, like a VCR, DVD player or satellite dish. It interprets and amplifies those signals and then sends them to output devices -- your television and sound system.

A surround-sound stereo receiver from Sony

A home theater a/v receiver and amplifier assembly actually combines several different components. Some even have a DVD or other media player built in. You can generally assemble a superior home theater system by buying the components separately, but most people buy one unit that does all these jobs because it is more cost effective.

The receiver's components are:

• Audio/video inputs for video sources (DVD player, DVR)
• Preamplifier
• Surround-sound decoder (aka signal processor)
• Power amplifiers for each sound channel
• Outputs for speakers and television

The path of the audio and video is pretty straightforward. The source component (DVD player, DVR, etc.) feeds a signal to the receiver unit. You choose which input component you want to feed to your output unit, and the preamplifier selects this signal and amplifies its line level a little bit.

The receiver is at the heart of a typical home theater system.

The receiver sends the video on to your television and sends the audio to the decoder. The decoder sorts out the different sound channels from the video signal, and then sends the information to amplifiers for each sound-channel output. These amplifiers are connected to the appropriate speaker or speakers.

Digital decoders and analog decoders handle the job differently. Digital surround sound is quite simple: When a company is producing a Dolby Digital^® program, for example, they encode six separate audio channels, specifically balanced for a Dolby Digital speaker setup. A Dolby Digital surround-sound decoder recognizes these different channels and sends them to the appropriate speakers.

Analog surround sound is something else altogether. The different analog surround-sound channels are actually extracted from the two standard audio channels that make up any ordinary stereo signal. This is commonly called 4-2-4 processing because the encoder essentially takes the rear and front channels and works them into the ordinary stereo channels, and a surround-sound decoder separates the four channels out again. See How Surrounding Sound Works for more information.

There are a wide range of audio/video receivers available. These receivers are often sold with all the speakers you need, as a complete home theater system. These systems run as low as $250 and as high as $2,500.

One of the most important differences between audio/video receiver models is what surround-sound formats they support. In the next section, we'll find out what the different formats are and see what they offer.

Which Surround-sound Format?

In the last section, we saw that audio/video receivers decode the surround sound information encoded in video signals and drive the appropriate speakers. Different audio/video receivers are equipped to decode different formats. Today, there are two main sources for home theater surround-sound formats -- Dolby Laboratories and Digital Theater Systems. Dolby Laboratories formats include various versions of Dolby Digital^® and Dolby Pro Logic^®. Digital Theater Systems has created a range of DTS Digital Theater Sound formats.

D-I-Y Surround Sound If you're really on a budget, you can rig your own surround-sound setup with four speakers and a regular stereo signal. See Accessing the surround Channel for more information.

Between the two companies, there is a dizzying array of sound options. So here's what you need to know:

• DTS encoding uses less compression than Dolby encoding. This means that DTS sound is clearer and sharper.
• However, DTS encoding is also less commonly used on DVDs and television broadcasts.
• Most DVDs have some Dolby sound options, and some also offer choices for DTS sound.

Fortunately, a lot of a/v receivers support a wide range of Dolby and DTS options. When you're choosing a receiver, you should decide two things: whether you want DTS support and how many speakers you want to use for your surround-sound setup. The most common options are 5.1, 6.1 and 7.1 surround, named for the number of channels. The ".1" indicates a channel for a subwoofer. The subwoofer channel carries low-frequency sound to give a bass boost and create a rumbling effect for certain special effects sounds, such as explosions and trains. These are the typical speaker setups and formats that will support them:

• 5.1 (5 speakers + subwoofer)
  A 5.1 surround-sound setup includes left, center and right front speakers. It also has left and right surround speakers. Dolby Digital, Dolby Pro Logic II and DTS 5.1 will all support this format. DTS 96/24 uses a 5.1 channel format to play audio at the same sampling rate at which it was recorded.

• 6.1 (6-7 speakers + subwoofer)
  A 6.1 setup takes all the speakers from 5.1 and adds a rear channel. Dolby Digital EX uses this format, splitting the one additional channel into left and right rear speakers. DTS-ES, on the other hand, uses a rear center speaker. DTS Neo:6 can also support a 6-channel format.

• 7.1 (7 speakers + subwoofer)
  Dolby Pro Logic IIx has separate channels for the left and right rear speakers, rather than splitting one channel and directing it to two speakers.

The sound system is what really makes a home theater experience complete, but the first thing you'll probably notice when you sit down in front of a theater setup is the television. In the next few sections, we'll see how televisions fit into the home theater.

Standard Direct-view Television

The biggest variable in home theater systems is the television. You can go with a large-screen, direct-view television and spend as little as $300, or you can spring for a front- or rear-projection television, which could cost several thousand dollars. The main factors that determine television price are size and picture resolution.

Direct-view televisions are the sets that most of us are familiar with. They have a cathode ray tube (CRT) and a scanning electron gun that paints the picture on a phosphor-coated screen. Good direct-view televisions deliver an excellent picture, but because of the tube technology, they are limited in size. The biggest direct-view television screen you can get these days measures 40 inches diagonally.

A 32-inch direct-view television from Sony: A direct-view television is certainly adequate for a simpler home theater system.

This is a pretty big picture, of course, and will work well in a basic home theater setup. You might even be content with a 27-inch model. The general rule for television size is that you want a screen that measures about one-third your distance from the screen (if you sit 9 feet from the screen, a 36-inch television screen would be perfect). These are the guidelines for standard televisions, because if your screen is bigger, or you sit closer, the scan lines that make up the picture will seem fairly large, which translates to a lower resolution. This is inherent in the standard television signal -- it has a set number of vertical lines of resolution -- the number of horizontal lines in one screen -- no matter how big your screen is. High-definition television (HDTV) has more vertical lines of resolution, so you'll be able to sit closer and still see a clear picture when watching HDTV-formatted video.

With a 40-inch screen, the Sony Wega is at the upper limit of direct-view televisions.

When you're shopping for direct-view televisions, pay attention to image contrast. A television with a darker screen will give you a better picture because there will be a stronger contrast between light and dark -- black will actually appear black, rather than gray. You should also look for a television with a flatter screen. If the tube is more curved, the picture will be more distorted and you'll see more glare from other light sources. A perfectly flat screen will usually give you the best picture.

If you need a very large television, you'll probably need a projecion television. In the next couple of sections, we'll see what the standard projection technologies have to offer.

Rear-projection Television

If a very large screen size is important to you, look into rear-projection televisions. These sets don't have the same size constraints as direct-view televisions because they don't use the cathode ray tube for the display. Instead, they use a projection screen. There are lots of different types of rear-projection televisions. They include:

• Cathode ray tube (CRT),which uses three CRTs, one each for red, green and blue. These can produce a great picture with good contrast but can also be heavy and bulky.
• Digital Light Processing(DLP),which uses one or three digital micromirror devices (DMDs) to create all of the pixels that make up the image. DLP sets also create a good picture, but gaps between the micromirrors can produce a screen door effect. Some users also notice a rainbow effect when moving their focus from one part of the screen to another in sets that use only one DMD.
• Liquid Crystal Display(LCD),which directs light through liquid crystals and magnifies it for projection. An LCD TV can be lightweight and slim, but it doesn't have a good black level -- the ability to produce a true black, which is important for good detail and contrast.
• Liquid Crystal on Silicon(LCoS) which is like a cross between DLP and LCD. LCoS doesn't have the screen door or rainbow effects that DLP can produce. It isn't as common as other display types, and some sets don't have a very good black level.

A 53-inch widescreen rear-projection television from Sony

Some rear-projection sets may have a smaller viewing angle than direct view sets. No matter where you sit in front of a direct-view television, the screen maintains the same picture quality. If you look at a rear-projection screen from an extreme angle, the picture may be much darker and you won't be able to see what's happening on the screen. Newer projection sets use high-quality screens that work well from most angles, but older sets may have a fairly narrow viewing area.

If you're looking to buy a rear-projection television, the main things to compare are size, resolution and screen quality. Even a top-notch picture can look muddy on a bad projection screen, so be sure to pay attention to screen material. Darker screens are better because they present an image with better light-and-dark contrast. You should also look for a screen made of glare-resistant material.

Front-projection Television

Standard front-projection televisions work in pretty much the same way as rear-projection televisions, but the system is not contained in a television case. They are set up more like a film projector -- the projector is a separate unit, and you center the television image on a separate fabric screen.

A high-end digital front projector from Sharp

The main advantage of a front-projection television is very large screen size. Since the components don't have to be packaged together, screen size is limited mainly by the room space -- what size screen you can fit in the theater, and how much distance you can put between the projector and the screen. Screens as wide as 200 inches are not uncommon. Projectors do vary in capacity -- make sure the projector is powerful enough to project a bright image across the room.

Most projectors work properly only in a darkened room. Consequently, they are really only suitable for a separate home theater space, rather than a family room or ordinary den. Since they are designed for watching movies, front projectors don't usually have a built-in television tuner: They don't receive television signals themselves, so they must be hooked up to a separate tuner (such as the tuner in a DVD player).

Front-projection systems use the same types of technology as rear-projection TVs -- CRT, DLP, LCD and LCoS . CRT systems can require professional installation, wiring and calibration. Other projector types can be easier to install, but they can also carry a pretty hefty price tag.

Flat-panel Screens

Flat-panel televisions don't have projectors or a scanning electron gun, so they're very thin and lightweight. If you plan to set up a home theater in a smaller room, this is a definite plus -- you don't have to worry about hauling a giant direct-view or rear-projection model in, and you don't need to figure out where to position a projector.

A flat-panel plasma television from Sony

The two primary types of flat-panel televisions are plasma and LCD. Plasma televisions create pictures with an array of cells that are a lot like flourescent lamps. Flat-panel LCDs are similar to the screen of a laptop.

Plasma and LCD displays have great picture quality, but neither has a very good black level. They're cool and convenient, but they can also be expensive. LCDs are limited in size -- you can get much larger plasma displays or projection TVs. While plasma displays can be huge, they are susceptible to burn-in -- an image left on the screen for a long period can cause permanent damage. Recently, consumers have reported burn-in due to the logos some TV stations place in the corner of the screen.

The real benefit of a flat plasma screen is its compact size, and if you have a small theater space, this may be reason enough to shell out the extra money.

DTV vs. HDTV

In addition to the television technology options, you also have to consider signal format when building your home theater.

For most of the history of television, there was only one kind of video signal -- analog. If you've read How Analog-Digital Recording Works, then you know that analog signals travel as a constant stream of information. In the case of video, the analog signal contains a stream of information telling a CRT television's electron gun how to paint lines on the phosphor screen. The problem with this sort of signal is that it degrades easily -- when you transmit video, you lose some of the picture quality of the original.

Over the past 10 years, digital television has taken its place alongside analog television. Digital video signals consist of bits of data, that is, sets of 1s and 0s. The advantage of sending information this way is that it can't degrade -- each bit has a set "either-or" value, so the signal will be exactly the same after transmission. Because they translate visual information so exactly, digital signals can carry much more detail than analog signals.

Widescreen Formats HDTV sets and some SDTV models have an impressive widescreen display. Traditional television has an aspect ratio of 4:3. This simply means that if the screen is four units wide, it's three units high. HDTV screens have a 16:9, or 1.78:1, aspect ratio -- the screen is 1.78 times as wide as it is high, more like a movie screen. For more information about the advantages of a wider screen, check out How Video Formatting Works.

The United States is changing its broadcasting from analog to digital television (DTV). Here's why:

• Because the signal can't degrade, digital televisions have superior picture quality.

• Digital signals are progressively scanned. If you've read How Television Works, then you know that a traditional television's electron gun paints only half of the picture lines in every pass. Digital video formats that feature progressive scanning paint the entire frame with one pass, which improves the fluidity of movement in a picture.

• Digital signals can provide much higher resolution than analog signals. Analog television supports standard-definition television (SDTV) resolution, which uses 480 horizontal scan lines of picture information. Digital broadcasts can handle this easily, and they can also allow higher resolutions, including high-defination telivision (HDTV), which boasts many more scan lines of picture information.

There's one important thing to remember here. General U.S. broadcasting is in the middle of a transition to DTV, not to HDTV. HDTV is the highest quality of DTV. During and after the transition to DTV, broadcasters will transmit signals in SDTV, HDTV and resolutions in between. Any new television set you buy will be able to read a DTV signal, but unless it's an HDTV set receiving an HDTV signal, you won't be getting all that extra resolution.

HDTV has a lot of advantages, but compatible sets also have a higher price tag. Right now, you can expect to pay $1,200 to $4,000 for an HDTV direct-view or rear-projection set, and $10,000 to $20,000 for an HDTV front-projection set.

82" rear-projection LCoS HDTV

If you'd like to have HDTV capability someday but you don't want to spend that kind of money now, you can get an HDTV-ready television. These sets have the necessary resolution capabilities to display an HDTV picture but don't have the necessary decoder to interpret the HDTV signal. Out of the box, they function just like traditional televisions, but you can buy a separate HDTV decoder that upgrades the set to display HDTV broadcasts. Some cable providers sell set-top boxes that will decode their HDTV signal. If your HDTV-ready television has a 4:3 aspect ratio, the picture will be cropped or letterboxed to fit the narrow screen size. For more information about HDTV and digital television, check out How HDTV Works.

There's one other important thing to keep in mind -- since the United States is in the middle of this transition, not all stations are broadcasting digitally. Some stations still broadcast analog signals, and these just don't look good on large-screen digital televisions.

To put a home theater system to work, you obviously need some way to watch movies or TV shows. To get the most out of your giant television and sophisticated sound equipment, you need a high-quality signal. In the next section, we'll look at the various video-source options.

Television Reception

Just because it's called a "home theater" doesn't mean it's for watching movies only. You'll definitely want to watch television in your home theater, too. These days, you have a number of options to choose from.

In the United States, the most popular options are broadcast television (the signals you can pick up with a rabbit-ear antenna) and cable television. Analog broadcast and standard cable signals both transmit video with 330 lines of horizontal resolution. This is better than VHS video, but not as good as DVD or digital television. Analog cable and broadcast TV also feature programming with Dolby Pro Logic surround sound, but they cannot carry Dolby Digital. Another option is digital cable, which generally has a better picture than traditional cable.

The main advantage of both broadcast and cable is price -- broadcast is free, and cable is generally less expensive than satellite programming. Additionally, cable and broadcast television always carry local stations, while satellite service may not.

If you want to get the maximum use out of your home entertainment system while you're watching television, you should consider getting a direct satellite system, such as DIRECTV,DISH Network. To get satellite programming, you need to buy and install a satellite dish, hook the receiver up to your entertainment system, and then pay the monthly fees, just as with ordinary cable.

The main advantages of a satellite system are that you can get lots of channels, and in September 2007 DIRECTV will offer more than 100 HD channels. Some satellite programming still uses Dolby Pro Logic surround sound, but other providers support Dolby Digital surround sound on select channels. Some providers have separate packages for people who want HDTV. When shopping for a satellite system, be sure you get one that can do everything you want, and ask whether HDTV broadcasting will require a different or more expensive satellite dish. Also, be aware that the weather can affect a satellite TV signal. Depending on your provider, you may also be unable to watch different stations on different televisions at the same time.

Another option is fiber optic service television, or FiOS, offered by Verizon. If you're lucky enough to live in an area that offers it, FiOS has several advantages. The cost of installing fiber optic cables is inexpensive and saves both you and your provider money, and the images are HD quality and suffer less from signal degradation (which means less pixilation or frozen images).

DVD Players, DVRs and Other Digital Playback

Most DVDs are formatted for one or more surround-sound formats and allow the picture to be presented in its original aspect ratio. For example, many DVDs present movies in widescreen format to match the way the movie looked in the theater, but they use a full-screen presentation for TV shows that originally aired that way. See How Video Formatting Works for more details.

A high-end DVD player from Arcam

VCRs It's no secret that a VCR can't give you the quality that a DVD player can. But there are still good reasons to own a VCR. For example, you might still need a VCR to watch all the movies you bought before distribution went digital, or to view that second season of Twin Peaks that's not available on DVD. If you're planning a home theater, consider upgrading to a hi-fi stereo VCR for better playback.

Older DVD players have high-quality playback, but they can't record things you watch the way VCRs can. However, several DVD recorders are currently on the market. Of course, a DVD recorder is a little more expensive than a standard DVD player. But if you want to record a lot of shows, a DVD recorder might be worth the price.

Another recording and playback option is a digital video recorder (DVR). Unlike VCRs, DVRs store video in digital form, on a hard drive. Actually, when you hook up a digital video recorder -- such as a TiVo unit -- all programming is recorded on a hard drive, and then sent onto your television set a few seconds later. This means that you can pause a broadcast TV show, then resume watching it where you left off.

These units don't provide the programming -- you have to connect another video source, like a cable outlet or satellite dish. You also have to connect the unit to a phone line -- it makes a daily call to update its programming information. (An exception to this is fiber optic service, which receives information directly through the video connection.) DVRs are a great option for people who want to record and watch a lot of shows. But the space on the hard drive isn't infinite -- on some models, you have to delete shows you have watched to make room for others you want to record.

The ReplayTV 4000 DVR from SONIC blue

In addition, several new digital video recording and playback technologies are emerging on the market. The two most prominent formats are Blu-ray and HD-DVD. Both use a blue-violet laser, as opposed to the red laser DVD players use. Blu-ray holds more data but is more expensive than HD-DVD. The jury's still out on which format will end up being the leader in the marketplace.

For more information on DVD players and DVD technology, check out our comprehensive article How DVDs and DVD Players Work. And, for more information on digital video recorders, check out How DVDRs Work.

One of the most important components in a home theater system is the speakers. Even with a top-of-the-line DVD player and audio/video receiver, the sound quality will be terrible if you don't have good speakers. In the next section, we'll find out about these essential components.

Speakers

Speakers vary a great deal in performance, as well as price. The main rule in shopping for speakers, whether for a home theater or your stereo system, is to try the speakers out in the store and decide what sounds good to you.

For your home theater system, you will need several identical, standard speakers -- the exact number depends on how many channels you want for your surround-sound setup. You'll also need an optional subwoofer speaker for bass sounds. Ideally, you'll want to get at least five identical speakers to ensure rich sound from all sides, but this might not be feasible, depending on your theater space and budget. If you're looking to save money, you could even use your television's built-in speaker as the central front unit, but it won't give you the best results. Different speaker models handle sound differently, creating an unbalanced surround effect. To get theater-quality effects, you should get three identical, full-size front speakers.

Sony digital subwoofer

Sony micro speaker Sony in-wall speakers

The main full-size speaker options are floor-standing units, bookshelf units and in-wall units. Floor standing units are the largest, and they generally have the highest performance levels, as well as the highest price tags. Bookshelf units and in-wall units are more compact, which is great if space is limited, and they perform very well. They may lack some bass range, but a good subwoofer should adequately compensate for this.

Connection Upgrades When you're shopping for components, people may suggest that you upgrade the connectors that go between parts of your system. Shoddy wiring can certainly hinder a system's performance, but exercise caution if someone advises you to swap out all of the manufacturer's cables with high-end replacements. The difference you experience might not be worth the money.

Many home theater systems use more compact, generally less-expensive speakers for the two rear surround channels. This will usually give you fine results, and is often the best solution if you don't have space for full-size speakers in your theater room. Some people even prefer these smaller bipole and dipole speakers because they generate sound in multiple directions, giving a more diffused sound.

Another thing to think about is the speaker technology. You may want to consider electrostatic speakers or planar magnetic speakers instead of the conventional dynamic driver design. See How Speakers Work to learn more about these different technologies.

To make it easier to assemble a home theater system, many manufacturers have put together home theater speaker packages, putting front and rear speakers together in a set. These packages vary in price and quality, so you should give them a "test drive" before you buy, just as you would with individual speakers.

If price is no object when you're putting together a home theater system, you might want to consider THX certification. In the next section, we'll find out what the THX system is all about.

Home THX

If you want a top-notch home theater, look into a THX^®-certified system. If you've read How THX Works, then you know that THX is Lucasfilm's set of standards for movie-theater equipment and arrangement. Lucasfilm has also come up with certification standards for home theater setup, and if you want the best of the best, this is the way to go. The chief aim of Home THX standards is to ensure the highest-quality re-creation of actual theater sound.

THX Ultra2 speaker system

There are currently two THX standards: THX Select, created with a 2,000-cubic-foot (57-cubic-meter) room in mind, and THX Ultra, for spaces with over 3,000 cubic feet (85 cubic meters). TXH Select2 and THX Ultra2 relate to receivers and amplifiers for the same two room sizes. THX has worked with electronics manufacturers to create equipment that lives up to the THX standards. THX has certified:

• Audio/video receivers
• DVD players
• Video screens - rated by their effect on acoustics
• Speakers
• Cables

A THX-certified home theater will cost you a good bit more than an ordinary home theater, because THX-certified components are mainly top-of-the-line equipment. If you just want a superior entertainment system in your home, you don't need to worry about THX systems. This sort of system is a luxury purchase, for connoisseurs driven to get the best possible sound out of their systems, or for folks with money to burn.

To find out more about THX home theater standards, check out the THX Web site.

Putting it All Together

Once you have all the components, it's time to set up the theater space. There are several factors to keep in mind when choosing and arranging the home theater room.

First of all, consider the architecture of the room. A home theater should be something like a movie theater -- you want an enclosed, rectangular room, with a good amount of space and not too much outside light. You need an enclosed space to get the best sound quality -- open rooms don't have ideal acoustics. If you are building a top-of-the-line theater, you may want curtained walls. This soft surface cuts down on disruptive echoes. For the same reason, it is generally better to have a carpeted floor than a wood or linoleum floor.

A custom-installed home theater system

Once you've decided what room to use, you need to figure out where to put everything. To find the best position for the television, just use common sense. It should be easily visible -- you don't want to crane your neck -- and it shouldn't be in a place that gets a lot of glare from outside. Put the television wherever it seems most logical, and build your system around that.

Getting the sound system in place is a bit more complicated. You should set the three front speakers up so that they are spaced evenly, all at about the same height. Also, make sure they are near the level of the television screen so that the sound seems to be coming from the action and actors you're watching on the TV. The idea is that you shouldn't be made aware of the speakers when you watch a movie -- your attention should be on the movie.

You have a couple of different options for arranging the rear speakers. Dolby Digital is designed for speakers positioned to either side of the listener, while Dolby Pro Logic systems should have the rear speakers behind the listener. In any case, the rear speakers should be mounted at the same height, spaced an equal distance from the listener. Of course, chances are you'll have more than one listener, so the spacing won't be equal for everybody. You can find the central listening position -- such as the middle of the couch -- and space everything according to that point, while still paying attention to other seats in the room.

It doesn't matter so much where you put your subwoofer. The low frequencies aren't directional like the higher frequencies emitted by the main speakers, so it can really go anywhere in the room. For the best rumbling effect, however, you should put the subwoofer on the floor or against a wall -- this will help the low frequencies carry through the room.

Once your television and speakers are in place, you'll need to calibrate them. Your television set may have a specific setup process for adjusting the color and brightness. Otherwise, you can use the THX optimizer found on many DVDs to perform your calibrations. You can also calibrate each speaker using a sound-pressure level meter. This will make sure that your speakers produce identical levels of volume.

Another thing to consider in your home theater is lighting. It's important that you don't have a lot of bright ambient light in the room, because this may cause glare on the screen or distract from the movie. But you also don't want a completely dark room, because the high contrast of the light from the screen may strain your eyes.

Ideally, a home theater should have soft ambient lighting connected to a dimmer. For the full theater experience, you can get an automatic dimmer and hook it up to the audio/video receiver. When you start up the movie, the lights will go down to a preset level on their own. Or you can control the lights with a remote control. Home theater systems can also be configured with curtains or cabinet doors operated by remote control.

As we've seen, the best home theater setup completely depends on your budget and your needs. If you just want a better entertainment system in the family room, a basic "home-theater-in-a-box" set, a DVD player and a good-sized television will be more than satisfactory. But if you want your own movie theater, with a huge screen and fantastic acoustics, you'll probably need to bring in a home theater expert and a contractor. The most important thing is to try everything out ahead of time to make sure your movies will look and sound great.