HOME UP to Home Theater


What is home theater?

While there may be as many answers to this question as there are salespeople wanting your money, my answer is rather simple. At it's most basic, a home theater is any system of electronics that allows you to play a movie, of your own choosing, pausing or rewinding at will, in your home. Thus we have two or three 'must have' items, those being a display unit (TeleVision or projector or monitor), speakers (may be built into display unit), and a source (Video Cassette Player/Recorder, LaserDisc, or DVD player). From this basic start, you can add any number of components to bring you closer and closer to a true theater experience.

Why would I want a home theater?

Consider that the price of attending a single movie at most theaters after 6:00PM is now around $8, and add on at least another $4 for popcorn, per person, and a night out at the movies gets rather pricey. Add in gas to get to the theater, and the total cost can easily be equal to or higher than the price of buying the movie on VHS or DVD, and four or five times greater than renting the same movie a few months later. Playing the movie in your home not only saves you money, however. You can pause the movie to grab a snack or use 'the facilities', rewind if there's something you just have to see/hear again, or watch the whole thing over and over as many times as you want! And don't forget that your snack selection is not only vastly cheaper than the theater's, but only limited by your imagination and culinary expertise.

What are the components of a standard home theater setup?

These days, most folks 'in the know' will agree upon several needed components for a good home theater system. In no particular order, they are:

Why do I need so many speakers?

Modern movies are typically recorded in at least four channels, and many are recorded with six. The four channel format includes a front left, front center, front right, and rear channel. In home theater, this would be called Dolby Pro Logic (DPL) surround. It's present on nearly every video tape, and even the lowliest receiver claiming to decode/process surround sound is capable of giving your this four channel format. The four channel format is not a discrete format, however. The center and rear channel are mixed into the front left and right channels, which allows all channels to be passed through any standard stereo connection, be it the output from your CD player, your VCR, or even your DVD player. The receiver/preamplifier extracts the center and rear channels from the other two. It should also be noted that in Dolby Pro Logic, both the center and rear channel have limited frequency response of approximately 100Hz - 7kHz.

In the six channel formats, all six channels are discrete, meaning at no point is any channel mixed with any other channel. The six channels are front left, front center, front right, rear left, rear right, and subwoofer (also called Low Frequency Effects, or LFE). All the channels except the LFE channel are full range, 20Hz - 20kHz. There are two competing formats using six channel sound in your home, Dolby Digital (DD) and Digital Theater Systems (DTS). You'll need either a laserdisc player (which is going the way of the record) or DVD player to obtain either DD or DTS. Both systems use advanced psychoacoustic modeling to generete compression algorithms which dramatically reduce the amount of data space needed to record five channels of full range audio, plus one subwoofer channel, onto a CD sized disc which also contains up to four hours of video!

The center channel is the most important speaker. It keeps on screen actors and sounds anchored to your video display, and produces the majority of sound you hear. While it is possible to use the front left and right speakers to trick your mind into thinking that the sound is coming from the screen, this effect typically only works well if you are sitting right in the middle of the two speakers, and we all know you can't put everyone in your room in the center of the couch!

The front left and right speakers let you enjoy the stereo soundtrack of a movie, as well as any sound effects placed there by the sound editors. It's important that all three front speakers be as closely matched as possible (ideally, they would be identical). This is to ensure that any sound which moves from one side of the room to the other is reproduced consistently, rather than changing as it pans from one speaker to another.

Having two rear speakers is really the only way to go, even if you only have the four speaker setup of Dolby Pro Logic. As the rear channel is used primarily for background effects (crickets chirping, wind blowing, rain), it's important that the sound field be diffuse and not easily localizable, just as it is in real life. With DD or DTS, this can be done at the studio, as the rear channels, just like the front left and right, are stereo. With DPL, while there are two rear speaker outputs, the signal they receive is identical. For this reason, if you are only using DPL, you should aim your rear speakers _away_ from your main sitting position to help diffuse the sound. Aiming the speakers at the ceiling or the rear wall is a good way to achieve this. If you are using DD or DTS, you can aim your rear speakers just as your front left and right, at your main listening position. Though many experts recommend the use of specialized rear speakers in either the bipolar or dipolar configuration, in my experience with DD and DTS, these are not necessary to produce the desired spectacur results. Just as with the front three, it's important that your rear speakers be as closely matched to the front as possible. Though some (such as the aforementioned experts) may argue, it's my contention that having all speakers identical is the way to go. This ensures that no matter which speaker is reproducing the voice of your favorite actor or blasting out those impressive action movie effects, the sound quality will not change if the sound moves from one speaker to another.

The LFE channel is used to reproduce very low frequency effects. While it is possible to route this low frequency information to other speakers in your system (for instance, the front left and right), this somewhat defeats the purpose. The intent of having a discrete channel for the LFE is to ensure that low frequency information goes to a speaker properly designed to reproduce the high volumes necessary, with low distortion. Keeping these frequencies out of the other five channels also helps to reduce distortion in their output, making for cleaner sound, particularly in the crucial midrange frequencies containing the human voice. Further, it's been determined that the ideal place for a LFE speaker is almost always in the corner of a room, while the ideal location for the remaining speakers is a few feet away from the side and rear walls, if possible.

All these speakers can assure that a movie played back on your system will sound exactly as the producer/director intended, and indeed extremely close to what you would experience in a professional theater. In fact, it can be argued that a home theater, if designed properly, can sound even better than your local theater! An additional bonus is that YOU control the volume, not the projectionist!

Can I use my current TV for a home theater?

That depends. If you only intend to play video tapes, the answer would always be yes. All TVs have an antenna input. This is the cylindrical threaded terminal on the back of the set which you screw/push your cable or antenna onto. Alternatively, this terminal could be connected to the output from your VCR. However, if you want to make use of the improvements that DVD has to offer, you will need a TV that has audio video inputs. Most of the televisions sold today offer these, but beware, some low end inexpensive models still may not! Audio video inputs are the same kind of jack you will find on the back of your receiver, or your CD player, or in fact just about any component in a stereo system. Red represents the right audio channel, white the left channel, while yellow represents the video signal. Better TVs also include an S-video connection, which is a four pin connection which looks somewhat similar to a PS/2 standard keyboard/mouse input on your computer. But wait, there's more! Many new TVs also include what is called a component video input. This splits the video signal up even farther, giving the ultimate in picture quality. A component input takes the form of three jacks (same size and shape as the other audio/video inputs) colored red, green, and blue.

If your TV has the yellow jack input, or the S-video jack input, you can use a DVD player. If you need to purchase a new set, I would recommend not even considering one without S-video. The difference in picture quality between the standard video input (also known as composite video) and S-video can be quite significant, depending on the quality of your TV. The difference between S-video and component video is said to be much less significant, and further, most receivers cannot switch a component video signal. At this point I would say that a component video input is not a must have item on a TV. This will change as the High Definition TV format grows in acceptance and comes down in price, but that is a very slow process, and I still would not recommend the purchase of a HDTV set.

How big should my TV or Projection Screen be?

Here's another tricky question that has several right answers. The generally accepeted minimum size is a screen with a diagonal measurement of 27". With the low cost of TVs now, there really is no reason to buy one smaller than 27" for your home theater. The upper limit of screen size is limited only by your budget. You can rather easily spend $50,000 on a top-notch front projector and 100" screen combination! There are a few things to keep in mind, however.

Once you get over 27" with a standard TV, you're going to more than likely need two people to move the set around. Single CRT sets come in sizes up to 36" diagonal, and the top Sony models in that size weigh around 250 pounds! You will find that rear projection, or what most people think of as 'big screen televisions', start at about 40" diagonal. You'll find that most of the 40"-45" rear projection sets weigh considerably LESS than a 36" standard TV. Certainly, the bigger your screen is, the closer you will come to having a real theater in your home. Most projection sets have some compromises compared to a standard TV. The screen is not nearly as bright, the contrast can be considerably lower, and the acceptable viewing angle may also be much smaller. With a front or rear projection setup, it's important to control the amount of ambient light in your room. With proper light control, there's no denying that a rear projection TV can provide a more satisfying and involving movie than your 27" set, for more people. For the ultimate in home theater nirvana, you'll want a separate projector and screen. This requires even more strict light control, as most separate projectors have the lowest light output of any display type. However, they have the potential to give you a home theater experience unrivaled by anything except your local cinema. Some may argue that a properly set up front projection system is better!

More to come in December!