What are the Basic Home Theater Components?
The very basic elements necessary to create a home
theater are a large screen television, a movie playing device, speakers, and
a surround sound capable controller or audio receiver. Understanding each
component's role is helpful when making choices on which ones to buy.
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Televisions
- CRT-
The original TV was a box that used a tube (CR
T)
to display an image broadcast from a television station. Most sets used at
home resemble this. Most of us have a TV with a screen that measures from
20-inches to 32-inches. As the screen got larger the box got heavier and
deeper. This means that a CRT TV with a 36-inch screen would have a depth
of about 26 inches and weigh about 200 pounds. Most of these are analog
but some are DTV capable. They, for the most part, have traditional 4:3
images. Some models offer 16:9 with 30-inch or 34-inch screens. CRT screen
sizes are limited because the size and weight of the set becomes
prohibitive as screens extend toward 40-inches.
- LCD
consists of a layer of a liquid crystal solution that is sandwiched
between two plates of polarized glass. When combined with a color filter,
a Thin Film Transistor (TFT) and a backlight, it creates a super-thin
television with an amazing picture. Extremely thin and lightweight, LCD
offers small screens at 17-inches or less that are extremely affordable.
In addition to notebook computers, you'll find LCD screens in portable DVD
players, pocket TVs, pocket PDA organizers, and handheld GPS direction
units. LCD Flat-panel TVs go up to about 30-inches. At below 17 inches in
size, these flat-panels are extremely affordable but, at over 18 inches,
their prices increase dramatically. A 30-inch LCD screen may run about the
same price as a typical 42-inch plasma screen. The LCD, however, is
extremely reliable for long life and image constancy, especial
ly
when used with rapid video images and video games. Plasma offers superior
contrast and color saturation but has a lower track record on longevity.
- Plasma
technology is a gas-like substance that, when squished between
two panels of glass and excited by electricity, creates a crystal-clear
picture. Originally developed in 1964, the technology involves charging
gas particles in a multiplayer chamber. It is the highest priced screen.
At about 4 inches thick, it is also the thinnest screen. Plasma offers
very large screen sizes. It offers bright, vivid color performance at
screen sizes from about 37-inches to over 70-inches. Of the flat-panel
screens, Plasma delivers the best contrast along with the purest black
colorations.
- Rear
Projection TV - The most common and affordabl
e
large screen TV system, Rear Projection integrates two or more small
internal television devices in a cabinet, magnifies the images and
reflects it with a mirror onto a translucent screen. This technology
enabled televisions with screen sizes up to 70 inches that were less than
25 inches deep. The drawback was that the resulting image was a magnified
reflection and suffered a loss of sharpness and brightness. Nonetheless,
the large size screen, the more compact size (compared to CRT), and the
affordability continue to attract many buyers and fans. There are
essentially two types of rear projection TVs:
- CRT Rear
Projection - Instead of having a single CRT pointed right at
you, three CRT tubes - a red, a green and a blue - are aimed together at
a focusing lens which bounces the picture off of a mirror and onto a
translucent, plastic screen, which presents the image that you'll look
at. Though these sets weigh a lot, they allow a larger screen in a box
that's more compact. What's more, the three tubes sometimes need
periodic alignment, or the red, green and blue will end up off kilter.
Color and contrast is very good but brightness is lost. You need to view
this TV in a dimly lit room. In addition, because you're looking at a
reflection the angle of view is somewhat restricted. This means that if
you look at the image directly from the front, picture quality will be
good. If you move up, down, left, or right, you may lose view of some or
the entire image. These sets, though they may have widescreen viewing,
are usually not considered for HDTV use and are the only rear-projection
TVs that use a tube-based system.
- LCD Rear
Projection - TV combines rear-projection with LCD technology.
This eliminates the need for convergence and special settings that CRT
displays require. The result is a high-resolution picture with less risk
of "burn-in" and greater versatility, like the ability to double as a
computer monitor. This TV shines a light through three LCD panels,
taking their red, green and blue moving images and reflecting them in a
similar fashion. The key difference is that LCD panels are thinner and
lighter than CRTs so the box is considerably lighter and thinner (16 to
20 inches deep). Rear-projection LCDs are known for high resolution and
brightness, which means that they can meet the demands of HDTV. The
brighter images allow more comfortable viewing in illuminated rooms and
LCD reflections offer a wider angle of viewing than CRT rear projection.
A downside of the bright image, however, is that 'black' colors and
shades are less dark and tend to appear as very dark grays. Many hardly
notice this.
- LCOS Rear
Projection - LCOS is 'Liquid Crystal on Silicon' and is a
more advanced type of LCD screen technology. LCOS offers a very bright,
sharp picture with virtually no degradation in contrast. Like LCD, LCOS
allows a slimmer and lighter box.
- DLP Rear
Projection - DLP (Digital Light Processing) is supported by a
single micro-display panel no larger than a postage stamp. Within this
tiny bit of technology, more than 1 million mirrors allow pixels to
refresh thousands of times per second. A color wheel then filters the
light into more than 16 million possible colors and delivers digital
images in astonishing clarity. A fully digital process, its advocates
tout it as perfectly suited for the increased performance of DTV and, of
course, HDTV. By minimizing the gaps between pixels in a projected
image, DLP projection systems create a seamless digital picture that's
sharp at any size-without the pixellation or "screen door" effect
apparent in other technologies".
- Front
Projection TV - Front projection projects the TV image onto a
screen. They are most commonly used with computers for presentations to
large groups of people. Most of these have inputs that permit connection
of DVD, VCR, and TV tuners so you can adapt them easily for home
entertainment. Image performance can be very good and you can use very
large screen sizes. Like a projected movie, however, you must view images
in rooms that are dark for best performance. Like rear projection models,
there are CRT-based, LCD, and DLP projectors available. Because of size
and weight, CRT front projectors have become least popular. Most models
are LCD and DLP, which are portable and lend themselves well to DTV and
HDTV applications.
Receiver or Controller
In most home theater systems, the receiver is the
brain of the system. It is where all the audio comes together and then. Most
home theater receivers have inputs and outputs, a built in tuner, surround
sound capabilities, built in amplifiers, and some even have a built in
equalizer. High-end systems will most likely have a controller instead of a
receiver. In this case, the controller is the most important piece in the
system. It processes the audio tracks coming from the source, divides it
into the various channels, and sends them to the separate amplifiers. The
controller also handles both audio and video signals and acts as a switching
device between the different sources.
- Amplifier-
Amplifiers are the power behind the system. Amps should be able to handle
the huge range of frequencies found in movie soundtracks and they should
be able to do it without distortion or clipping.
- Tuner-
A home theater system utilizing a controller instead of a receiver will
need a separate tuner for radio stations. Most tuners today are digital
with multiple preset buttons and scanning features.
- Equalizer
- Once a room's acoustics have been physically optimized as
much as possible, the addition of an equalizer will fine tune the room's
acoustics and balance the frequencies.
CD Player
Home CD players today come in three basic varieties:
single play, changers or "mega" changers. The most popular players are the 5
or 6 disc changers but as disc collections have grown, mega changers with
100-300 disc storage and play capabilities have also become more popular.
DVD Player
Stands for Digital Video Disc or Digital Versatile
Disc, depending on who you ask. DVDs look just like CDs, but contain high
quality video and multi-channel audio. Some home theater systems come with
DVD players and some don't, but using digital sources like DVD are the only
way to take advantage of digital surround sound modes like Dolby® Digital
and DTS.
VCR
Still a common playback source is the VCR. Its
biggest advantage is recordability. Disadvantages of the VCR include tape
wear and damage, non-instant access, and on a large-screen TV, the
resolution just doesn't compare with the resolution achieved with DVD
players.
Digital Video Recorder
A digital video recorder (DVR) is like a VCR on
steroids, allowing you to record as many as 140 hours of programming onto a
built-in hard drive, eliminating the need for tapes. Digital video recorders
let you record shows, pause live TV and fast forward to the best parts,
without needing tapes or discs. Watch the shows you want, when you want.
DSS Reciever
A satellite dish (about the size of a large pizza)
receives a signal and connects to a Digital Satellite Systems (DSS)
receiver. They receive digital satellite signals that carry superior image
capabilities similar to a DVD with CD quality sound. They're easy to setup
and tune in and will be able to accept future television standards like high
definition television and six-channel surround sound. Monthly service plans
cost about the same as standard cable service.
HDTV Receivers
Not all HDTVs come with built-in high definition
receivers. These are HDTV monitors. While they’re capable of displaying
high-resolution 720p (720 lines of information in progressive scan format)
and 1080i (1080 lines of information in interlace format) pictures, these
TVs can’t do the job alone. Rather, HDTV monitors must be connected to a
separate HDTV receiver. It’s this receiver that gathers and translates
digital information into a form understood by the HDTV monitor so it can
then display the picture.
Line Doubler
The quality of a projected video image on a large
screen can be improved in quality by using a line doubler. A video image is
made up of approximately 500 horizontal scan lines, but because of the way
it scans, only half the lines are shown at one time. A line doubler presents
all the scan lines at the same time, thereby increasing its sharpness. At
the same time it cleans up imperfections in the video signal. A line
quadrupler does the same and adds information between the scan lines for
even higher resolution.
Interpolator
An alternative to a line doubler or quadrupler is an
interpolator. It also increases the quality of a projected video image on a
large screen but in a different way. An interpolator determines the optimal
scan rate for the monitor used. It then creates and fills in the picture
information to precisely fit that monitor for the best quality image. An
interpolator also changes aspect ratios on the monitor to match the format
of the source signal. An example would be a letterbox image can be made to
fill a screen eliminating the top and bottom banding. An interpolator mixes
video and computer images which electronically are very different, and until
now could not be mixed. This capability may become more essential in the
future as video and computer applications converge.
Speakers
Since sound attributes to half of the home theater
experience, it's a good idea to get the best speakers you can afford. Like
amplifiers, speakers should be able to reproduce a large frequency range
clearly without distortion. No two speakers sound alike so selecting them is
often a matter of personal listening preference. Any speaker placed within
2' of the television needs to be magnetically shielded to avoid signal
breakups and picture distortion. Most speakers marketed toward home theater
are shielded, but it is an important item to verify.
A home theater needs at least six speakers: left
front, r
ight
front, center front, two surrounds, and a subwoofer or bass module. For a
DTS or Dolby Digital system, all six of these speakers should be capable of
a full range of sound and be fairly equal in quality. For anything up to and
including Pro Logic technology, there is some differentiation.
- The left front and right front speakers
carry the bulk of the music and sound effects in a home theater. These
speakers should be high quality and able to handle a wide range of sounds.
- The center speaker is the primary carrier
of dialogue and should therefore be the same quality as the left and right
front speakers. Ideally, it should be the exact same speaker, or at least
matched in quality and power.
- For most home theater systems, the surround spe
akers
can be smaller in size because they do not need to carry the booming bass.
They should put out at least half the power and match the front speakers
as close as possible in sound quality and balance for an even sound.
- Subwoofers reproduce the low bass sounds
that make movie effects like explosions, sonic booms, crashes, and
dinosaur footsteps seem realistic. These are the sounds that really pull
you into the experience and a good subwoofer or bass module is needed for
a full effect.
Rack System
You can see by the list of equipment that a home
theater system can take up a lot of room. A rack system organizes the
components and helps to keep pieces orderly and neat looking. Some rack
systems come with rollers which slide completely out of the cabinetry making
it easier to get at the cables on the back to make changes. Modular rack
systems also make it easy to add components in the future.
Cables & Interconnects
They may seem relatively unimportant compared to the
rest of the equipment, but cables and interconnects can make a difference
between a good sounding system and a great sounding system. This is true on
any size system from the low end to the highest quality. The signals between
components and speakers need to flow unrestricted or the output will suffer.
Cables should be a heavy gauge and the connectors
should be gold plated. Some experts even say to allow as much as 10% of your
home theater budget for cable.
Remote Control
Most electronic equipment has a remote control.
Imagine a whole rack full of components each with individual remotes -- you
know that the coffee table probably won't be big enough to handle them all!
But you still need to be able to control all those devices. If you happen to
purchase all your equipment from the same manufacturer, you might be able to
control everything from the receiver remote. But most people don't buy
everything from one manufacturer and that's where a universal remote comes
in.
There are a number of sophisticated systems out there
that will not only do the job but make things a little simpler. A high-end
touchpad system we installed includes a tabletop device with a large screen
programmed to control each component. There's a screen for each component
with icons that represent different functions. Simply press the symbol on
the screen and it performs that function.
The remote transmits information by radio waves
rather than the traditional infrared waves so you can keep the components
behind closed doors and still be able to operate them. Inside the rack is
the remote receiver that takes the information from the radio waves,
processes it and sends a command via infrared through wires to the
component.
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the television at nearly equal heights to each other.