by Maurice Lewis
Amplifier
An amplifier takes an audio signal and heightens it to a level so that your speakers can hear it.
Aspect Ratio
You're going to hear a lot about this term if you ever do any research or reading on video components. In simplest terms, the aspect ratio is the ratio of the width of a video picture to the height. The standard in most NTSC television screens is an aspect ratio of 4:3, while the HDTV adheres mostly to a 16:9 standard. Movies in general tend to be 1.85:1 or 2.35:1. See more info on Aspect Ratios in the video section.
Center Channel Speaker
The center channel speaker, often placed on top of your television set, handles most of the dialogue and action sounds in a traditional surround sound format.
DVD (Digital Video Disc/Digital Versatile Disc)
The DVD is a CD-sized, 100% digital disc which uses MPEG compression. The end result is an extremely sharp picture, CD-quality sounds, and the ability to include additional information besides the film on the disc.
DTS (Digital Theater Systems)
Movie theaters use this sound format, which employs 8-channels to surround sound effect, and the sound is played on CDs.
Dolby Digital
Commonly referred to now as Dolby AC-3, this sound format is the 5.1 channel home theater surround-sound system. The channels utilize 5 speakers, two front, two rear, and one center speaker, plus a subwoofer.
Dolby Pro-Logic
A 4 channel home theater surround-sound system which is prevalent in about all stereo receivers available today.
Dolby Surround
A 3 channel home theater surround-sound system.
Front Projector
Projection screen units come in either front or rear projection units. Separate front projection units, commonly found on airplanes, project the viewing image onto a screen.
HDTV
You've all heard of this unit, and are probably wondering how it's eventual use will impact your current television unit. Well, we've been waiting for HDTV for a long time, and, as always, they are still being called the future. HDTV employs a widescreen aspect ratio of 16:9 (as opposed to the 4:3 ratio used in standard NTSC televisions today). HDTV should have at least 1000 lines of resolution and will supposedly be based on a digital broadcasting format in the United States (projected date of full implementation, 2006, so don't go throwing out your existing television quite yet).
Letterboxed-Films
Since films now use a wider aspect ratio than televisions, black bands are placed on the top and bottom of the screen, to allow for the original aspect ratio to be viewed. Otherwise, a great deal of the action would be missed.
Main Speakers
The two front left/right speakers in a home theater system. These speakers should be able to handle a full range of sound.
NTSC
Currently, television in the United States, and some other countries as well, is broadcasted in the NTSC standard, which has a 4:3 aspect ratio and no more than 525 lines of resolution.
PAL
In Europe, the Middle East, and many other areas, the PAL standard is employed to broadcast television. While the aspect ratio, for the most part, is the same as the 4:3 found in NTSC broadcast, the resolution can go higher, up to 625 lines.
Pan and Scan
When a film with a widescreen aspect ratio is being viewed on a NTSC screen with a smaller aspect ratio of 4:3, and letterboxing is not employed, much of the picture is missed. As a result, someone somewhere must decide which is the most important part of each scene, and that is the only part that is viewed in the "Pan and Scan" technique (called this because if another part of the scene is to be viewed, the picture "pans" over to that part of the scene).
Rear Projector
Another means of projecting an image onto a home-theater screen besides the typical front-projection system. Exactly as the name implies, there is a screen and the image is projected from a unit placed behind it. Must be perfectly calibrated to work properly.
Receiver
The receiver is what I like to refer to as the "brain" of a home theater system. It is the audio unit which decodes sound formats, switches between different sound inputs (VCR, DVD, CD systems, radio), and amplifies the sound while sending it out to the speakers. A receiver combines a processor, an amplifier, an A/V switch, and usually an AM/FM tuner.
Resolution
Every television picture is actually a series of lines, known as the lines of resolution. The more lines of resolution, the sharper the picture. Therefore if someone is referring to a sharp or weak resolution, they are actually referring to a high or low number of lines on the television set.
S-Video
A video connection most recommended for connecting DVD players to televisions in which the brightness and color are separated when transmitted from the player to the television, often resulting in a purer overall signal, at least to purists.
Subwoofer
The subwoofer, my personal favorite speaker, handles the bass of movies and music. Traditional speakers have a limited frequency range, and therefore miss out on parts of movie soundtracks or music that have bass in lower frequency. The subwoofer is there to pick up on what the normal speakers miss. It really gives that kick, that oomph to a home theater system. If you do not have a subwoofer, you are quite simply missing out on sound that exists that you cannot hear.
Surround Sound
In basic terms, surround sound is the concept of sound "surrounding" the audience, usually when speakers are placed both in front and behind them. The effect, however, is minimal unless properly decoded by a receiver to take advantage of the speakers' placement.
Surround Speaker
Surround Speakers are often referred to by rear speakers, terms which really anger true home theater enthusiasts (not me, I tend not to get into a tizzy over these things). These speakers are used to create background and dispersed sound, but rarely any major action or dialogue sound.
THX
The ultimate, and most expensive, in home theater entertainment. A technique used to develop sounds for films, THX has become a standard by which films, videos, and home theaters are created. The technique was developed by George Lucas, whose first student and full-feature film you will recall was named "THX-1138." Again, it is not a surround sound format, but a standard by which home theaters and videos are measured to ensure the proper transfer of the film sound to the home.
Widescreen Film
A film whose aspect ratio is wider than the traditional 4:3 ratio found in standard NTSC television sets. Since the aspect ratios are wider than that found in the set, the film must adapt. Most popular among film enthusiasts is "letterboxing" which allows the whole film to be seen in its original ratio. Most hated among film enthusiasts is the "pan and scan" techniques or the less frequently employed "anamorphic squeezing" technique. This latter technique is exactly what it sounds like, the squeezing of a widescreen film onto the screen, so characters and visuals can become distorted and skinny. |
