High-definition television: Why bother? Surely HDTV is a plaything for the rich and self-indulgent, some cryptic form of digital television designed for Freemasons, just one more ridiculously overhyped and overpriced technology aimed at parting care-worn folk from their hard-earned cash. Right?
Wrong. The analog television standard we’ve been using since just after World War II is ludicrously obsolete. It was designed for round-cornered five-inch pictures that were mere portholes compared to the big screens that today’s home theater buffs demand. Trying to build a home theater system around 1948-vintage technology is like riding a horse in the slow lane.
Analog TV is dying. Get over it.
Now that HDTV has been around for a few years it is possible to buy a set with full high-definition capability at a surprisingly reasonable price—less than $1000 for a direct-view set, and a little more than $1000 for a rear-projection TV—though of course the fashionable flat-panel displays cost more. You can get HDTV signals via antenna, cable, or satellite.
But what kind of HDTV is right for you? Wander into a chain store and you’ll see TV sets grouped into a handful of categories. They include direct-view analog TV, rear projection, front projection, and the oh-so-desirable flat panels. Let’s look into each one and see how it relates to the HDTV standard.
For Starters
For that purpose we’ll need to briefly define HDTV. It embraces two formats: one with 1080 by 1920 pixels, and one with 720 by 1280 pixels. Any kind of digital TV can convert signals to its own native resolution—but to see true HDTV you must feed a HD signal into a HD-capable display.
How big of a HDTV do you need? As a very loose rule of thumb, minimum viewing distance should be three times the height of a widescreen set (HDTV is a widescreen medium) or roughly 1.5 times the diagonal measurements that manufacturers and retailers use. To put that another way, the screen diagonal should be at least two-thirds of the viewing distance.
If you don’t intend to change the viewing distance in your room, screen size is the variable you need to look at. Whatever you buy should look right at your preferred distance. The screen should be large enough to dominate your field of vision and immerse you in a story or event—but not large enough for pixels or scan lines to be visible.
Direct-View HDTVs
The smallest and least expensive TVs are called direct view. In other words, they have a single picture tube. Direct-view HDTVs range in size from 27 to 36 inches. Since tube TVs define the low end of the market, many of those you’ll see on display are analog—you can’t assume that every TV on the shelves is a HDTV.
Direct-view HDTVs may be either widescreen or non-widescreen. Widescreen sets have an aspect ratio (screen proportions) of 16:9, or 1.78:1, the same as widescreen DVD, and similar to what you’d see in a movie theater. Other sets have the more traditional 4:3, or 1.33:1.
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Widescreen sets are better for viewing contemporary movies and the increasing number of widescreen sports telecasts. Nonwidescreen sets excel at older movies and sports on analog TV channels. Either kind can display both wide and non-wide programming with the addition of blank horizontal or vertical bars.
A more severe limitation of the direct-view TV, HD-wise, is that the shadow mask at the front of the tube doesn’t have enough perforations to display any HDTV format at its full resolution. If the holes are made smaller and more numerous, brightness declines, and most people prefer a bright picture over a bland one.
Rear- and Front-Projection HDTVs
You’ll get a bigger picture from a rear-projection HDTV. Screen sizes range from 40 to 70 inches and occasionally as much as 82. Better yet, the lowest-priced type of RPTV actually generates the best picture!
We’re talking about sets that use a trio of cathode ray tubes and optics to produce a picture.
DLP sets now come in 1080 by 1920 pixel resolution as new TI chips are finding their way into production products. Only the biggest sets with nine-inch tubes can display 1080 scan lines at full resolution. Most RPTVs have only seven-inch tubes. But even that limitation is a hidden strength: those seven-inch tubes slur the scan lines together to produce an almost perfectly seamless picture.
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Tube-based RPTVs do have a downside. The tubes have to be aligned by a technician to achieve perfect performance, they’re subject to burn-in from videogame use, and they’re bulky, so CRT-RPTVs jut out from the wall.
All these disadvantages vanish when you move up in price to RPTVs with microdisplay (meaning chip-based) light engines. DLP sets use micro-mirror chips; LCD sets use liquid crystal panels. Throw away those fat tubes and the set’s depth dimension shrinks nicely.
However, although they cost more, microdisplay RPTVs have a few weaknesses. One is resolution: they support HDTV’s 720 by 1280 line format (about 900,000 pixels total) but not the 1080 by 1920 format (about 2,000,000 pixels). They also can’t reproduce true black—it tends to come out charcoal grey.
Front-projection HDTVs produce the largest pictures. They work the same way as rear-projectors, except that the screen is separate, and they work best in a darkened room. You’ll have the same choice between tube- and microdisplay-based devices.
Watch the resolution specs. Not all front-projectors are HD-capable. Also, as more pro-level manufacturers enter the front-projection consumer market, be sure that you buy a model designed for home theater, with the ability to adjust screen shape, as opposed to something optimized for boardroom presentations.
Flat-Panel HDTVs
The sexiest bodies on the home theater beach are flat-panel TVs. They cost more than any other kind, but for many, the form factor is worth the extra cost. Who can resist a TV you can hang on the wall?
Notice we didn’t say HDTV. Some flat panels are high-definition-capable and others are not. You’ll have to read the specs to be certain. Resolution must be at least 720 by 1280.
Those with lower resolution are not high-definition but standard-definition, to use the industry euphemism. You can feed a HDTV signal into an SDTV display but you won’t see it at maximum sharpness.
The smallest flat-panel sets (and most expensive per square inch) are LCD TVs. LCD flat-panel TVs now come in sizes up to at least 42 inches and a 65-inch Sharp is hitting shelves just about now. Check the refresh rate—liquid crystals don’t move as fast as they should and LCD TVs often show motion artifacts.
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Plasmas have hit 70 inches and will probably hit 80 soon. They’re sometimes called gas plasma because each pixel is a tube of neon gas stimulated by current. The pixels have visible spaces between them, creating a kind of screen-door effect, so viewing distance may have to be greater. Beware of models with shiny screen surfaces that reflect room light.
Side Dishes
A high-definition display will look its best only when fed a high-definition signal source. There are three ways to get HD signals into your system: via broadcast, satellite, or cable.
To grab HDTV from the airwaves you’ll need both an antenna—which might be indoor or outdoor, depending on reception conditions in your area—plus a broadcast tuner. Your HDTV may have a built-in tuner. In sets of a certain size, the FCC even requires it. However, if your set is just HD-ready, a set-top box will do the trick.
Both DirecTV and EchoStar support a limited number of HDTV channels. You will, however, need an HD-capable satellite receiver to access them. Some satellite dishes come with built-in broadcast antennas so you can double-dip.
Your local cable company should be able to provide an HD-capable cable box. A limited but increasing number of digital cable ready HDTVs can operate without the box. They come with a CableCARD slot that can accept a decryption card from the cable company. Slip the card into the set and goodbye cable box.
You might be wondering whether your HDTV can display high-def signals from DVD. The answer is no simply because high-def DVD exists only as a pricey product offered in Japan. It will come to the United States eventually but yet another ridiculous format war—between the Blu-Ray and HD DVD formats—is likely to slow high-def DVD’s penetration.
However, even the existing standard-definition DVD can look pretty good on a digital display. DVD players with progressive scanning reduce distracting motion artifacts.
A good high-def display minimizes motion artifacts without any assistance. When you’re eyeballing sets at the store, to assess the quality of their video processing circuits, just look for rapidly moving diagonal lines. If diagonal lines appear jagged, the set’s video processing is doing a poor job. An American flag fluttering in the wind is perfect demo material. Even a facial closeup can be revealing: Do the pores and lines on a speaking face remain mostly in focus?
Finally, the HDTV broadcast format does support 5.1-channel Dolby Digital surround sound, and that’s the other half of the home theater equation. If you’re adding a high-definition display to your system, you owe it to yourself to go all the way with surround sound that engulfs the senses, and that means going beyond the set’s built-in speakers to an external surround system with good-sounding speakers. True, laying speaker cable to the back of the room is a pain, but once you’re seen and heard home theater the way it ought to be, you’ll never want to go back.
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Mark Fleischmann is the author of Practical Home Theater (www.quietriverpress.com).
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