TV and Projection Systems

Sound without the picture in your Home Theater is just as bad as a picture without the obviously, you need a TV or Projection system as a critical part of any Home Theater system!

Understanding the choices and the various technologies is an important prerequisite to choosing a TV set, and this process has become a lot more complicated than it used be.

Not only because our North American TV broadcast system, now 50 years old, is moving from analog to digital, but because the new digital technology also includes a high-definition TV (HDTV) standard with a different screen shape.

And if that isn't enough, the actual TV display technology is rapidly changing and evolving. Nevertheless, for most of us, the tried-and-true cathode-ray tube (CRT) direct-view TV set remains the most familiar, and on average it's still the least expensive.

What type of set you choose, be it rear-projection, direct-view CRT, flat-panel, LCD, plasma, DLP, or front-projection, will be influenced by how much you are willing to spend initially and whether or not you want a TV that is HDTV-capable and ready to display the stunningly crisp pictures that digital HDTV can provide.

And of course, the screen or image size and shape also directly influences the cost of the set. Analog CRT direct-view sets use a picture tube coated with color phosphors that illuminate when struck by an electron beam from the back of the picture tube. CRT sets mostly use a 4:3 aspect ratio (four units of width to three of height), the almost-square format we've grown up with. Part of the new HDTV standard is a 16:9 widescreen aspect ratio, much closer to what we see in movie theaters and the most common format for movies on DVD.

Widescreen 16:9 sets are more expensive but they will deliver sharper images from a DVD or off-air widescreen programming. If you use a 4:3 set to view 16:9 movies on DVD or TV shows shot in widescreen format, some of the TV set's clarity or "resolution" is wasted on the black bars at the top and bottom of the screen. If you stay with an analog set, check the type of "comb filter" the set uses, because it has a direct effect on picture clarity.

In ascending order of quality, comb filters are: two-line comb (fairly good); three-line comb (much better); 3-D digital comb (the very best).

Analog direct-view 4:3 CRT sets are practical up to 36-inch screen sizes; in a 16:9 HDTV widescreen version (typically 34-inch and 38-inch diagonal), the picture tubes are costly, and so are the sets.

Consequently, lots of new 16:9 HDTV-capable sets use rear-projection (RPTV). These have three 7-inch or 9-inch CRT tubes inside (one for each primary color) producing an image that is magnified and projected with a mirror onto a large translucent screen at the front of the set. Periodically, you have to "converge" or align the three color images because the alignment drifts over time, producing color fringes around the edges of objects and a fuzzy picture.

So look for RPTV sets that have "auto-convergence" circuits that will automatically realign the color tubes or at least display a pattern over the full screen that will let you manually do convergence using the remote control.

Rear-projection sets, both widescreen and 4:3 models, typically begin with 43-inch screens and go up to 65 inches diagonal. These sets have improved tremendously in recent years and most are bright enough to view in a room with only slightly dimmed room lighting.

You may also opt for an HDTV-capable 4:3 rear-projection set if you want; it will display conventional TV images full-screen and HDTV or DVD 16:9 images "letterboxed" with black bars at top and bottom and some sacrifice in resolution. No matter which type (HDTV 16:9 or analog 4:3) of RPTV you select, look for a bright even image both directly in front of and at angles to the screen. Sets vary considerably--some will "hot-spot," with the screen center brighter than the edges, and others will noticeably darken at angles away from the center. Be sure you sit down or crouch to look at RPTV sets, because the images are always dimmer viewed from a standing position.

Stores should elevate the sets (many do not) so your eyes are even with the center of the screen, or there should be a couch or chair from which to view the sets.

If you stay with an analog set, you can expect to use it for five years or more because the transition to digital TV broadcasts and HDTV is moving very slowly.

But if you want the sharpest possible DVD pictures, as well as the ability to watch digital HDTV programming now and in the future, you should consider a widescreen HDTV-capable digital set. You'll likely keep the set for 10 years or more, and it will deliver sharper DVD images as well as improved conventional TV pictures from cable or satellite.

All the HDTV-capable sets have component-video inputs for maximum picture clarity from DVD, as well as the ability to display several of the various HDTV formats, which include 480p, 720p, and 1080i. Two of these (480p and 720p) use progressive scan, which eliminates the visible scanning lines of conventional interlaced TV pictures to deliver a smoother, more film-like image.

At the moment, there isn't a huge amount of HDTV programming out there, but it is increasing, and some cable-and satellite-TV systems are regularly running HBO movies, a few TV shows, and special programs in HDTV.

If your bank account is unusually healthy, you can seriously consider some of the latest high-tech TV displays. The plasma flat panel, only a few inches thick, can yield stunning images, although blacks have a tendency to be a bit grayish and screen size is mostly limited to 40 or 50 inches. Be prepared for sticker shock because prices start at about $7,000 (three years ago, plasma sets were $20,000 or more)!

One of the most exciting new TV display technologies uses digital light processing (DLP), based on a Texas Instruments Digital Micromirror Device (also called a DLP chip). It contains microscopic reflective mirrors that are switched on and off thousands of times per second, digitally controlled by the video signal. These produce a brighter, sharper, and smoother image than LCD front or rear projectors, and tend to be more expensive, but prices are dropping.

Several new front DLP projectors are smaller than a slide projector and can produce near-HDTV sharpness. But keep in mind that any front-projection TV image looks its best in a completely darkened room, so plan accordingly.

Front projectors are best suited to a dedicated home theater, not casual viewing in a bright family room. Prices begin at around $3,000 to $5,000.

DLP technology is also used in rear-projection sets, which are capable of very bright, sharp images in non-darkened rooms. The big advantage of LCD projectors, both front and rear, is that they require no convergence adjustment.

Years ago, LCD projectors had rather coarse pixel displays so the TV image had a kind of screen-door fuzziness. But now they have improved to a level where new ones are capable of HDTV sharpness.

One last little audiolofft secret: just because a TV uses digital circuitry doesn't necessarily mean that it will display true HDTV clarity. There are three divisions of quality within the digital TV standard: Standard Definition, Enhanced Definition, and High Definition. So inquire what the set is capable of in its maximum resolution mode.

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