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Author: Dougaha Three stars, 500 posts Feste Award Nominee! Old School Fool Add to my Favorite Fools Ignore this person (you won't see their posts anymore) Number: of 10536  
Subject: FAQ - Buying a TV - Attempt #1C Date: 1/4/2006 2:31 AM
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High Definition TV is digital, but not all digital is HDTV.

Not every channel will be HDTV.

Your TV will still work after the digital “switch”, but with some limitations.


Alright, ladies and gentlemen, here is attempt #1(c) at writing the official FAQ for "Help With This Home Theater". I am writing this from the perspective of someone who's in the business. (I sell electronics for a living in a major retail environment in the Midwest).

Let me begin by saying that this stuff can get very, very complicated. My goal is to try and simplify all the technology stuff without completely dumbing it down. I'll be honest; buying a TV can be a harrowing experience these days.


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First, let's define some terms so we can be clear later on in the FAQ:

NTSC: National Television Standards Committee; This is the current standard analog signal for cable television. Some people jokingly referred to it as “Never the Same Color”

Digital Broadcasting: Using 1's and 0's instead of an analog radio wave to send a signal to your home. TWO IMPORTANT THINGS TO KNOW, AND I CAN'T EMPHASIZE THIS ENOUGH: HIGH DEFINITION IS A DIGITAL BROADCAST, BUT NOT ALL DIGITAL BROADCASTING IS HIGH DEFINITION.
- Digital TV basics: http://www.pbs.org/opb/crashcourse/
- HDTV and Digital TV: http://hometheater.about.com/cs/beforeyoubuy/a/aahdtvfaqs2a.htm

ATSC: Advanced Television Standards Committee, this is the term for an over the air (OTA) digital television signal

QAM: Quadrature Amplitude Modulation. Pronounced kwom, this is the term for an unscrambled digital cable signal. This is how your TV in the future will receive a cable signal if it doesn't use a cable box. Premium channels like HBO, Showtime, ESPN, etc etc will typically not pass through a QAM signal because the cable company has to make their money somehow.

High Definition: The best kind of digital broadcasting, this signal offers a resolution of either:
- 1280 x 720 pixels, progressive scan (720p)
- 1920 x 1080 pixels, interlaced scan (1080i)
- 1920 x 1080 pixels, progressive scan (1080p) This is an up and coming technology, not really available yet, but many TV's are being produced with this capability in order to handle the new Blu-Ray and HD-DVD players coming out soon. See the following: http://reviews.cnet.com/4520-6449_7-6361600-1.html?tag=more


Enhanced Definition: A step down in resolution from high definition, this signal offers the following:
- 852 x 480 pixels, progressive scan (480p) (slightly better than DVD quality)

Standard Definition: The most basic digital broadcasting standard, this signal offers the following:
- 704 x 480 pixels, progressive scan (480p)
- 640 x 480 pixels, interlaced scan (480i)

Progressive scan – “painting” a picture on a television using double the normal frame rate and double the number of lines compared to a standard analog signal. (Normal is scanning every other line, 30 times / second, progressive scan is every line of the picture scanned 60 times / second);
- More info here: http://hometheater.about.com/od/beforeyoubuy/a/progressivescan.htm
- And here: http://boards.fool.com/Message.asp?mid=23493808


Interlaced Scan – painting a picture on a television using every other line at 30 times / second.
- See also: http://hometheater.about.com/od/beforeyoubuy/a/progressivescan.htm

DVI – Digital Visual Interface, this is a connector on the back of TV's used to plug in HDTV set top boxes and certain DVD players. Carries digital video only, no sound.

HDMI – High Definition Multimedia Interface, this is essentially an updated version of DVI, but it's a smaller connector and also carries the digital audio signal with it. Looks like a USB connector and is often confused for USB, but they are different.


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Antenna Issues

What is the deal with antenna broadcasting? Why is this even an issue?
- Well, a lot of people still receive their TV signal from an antenna.
- Some people have satellite TV and get their local stations from an antenna

What kind of antenna do I need to buy for digital TV? Some special digital antenna?
- The short answer is no. The same antenna that picks up your current TV signal will also pick up a digital signal in the future.
- The longer answer is that it depends on where you live. Because a digital signal is created with 1's and 0's, there is only on or off, good or bad signal, there's no in between. So if you live in an area where you get a weak signal, you might need a better or larger antenna. See the following: http://www.antennaweb.org


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Next, let's talk about TV technologies: There are currently somewhere around eight (8) different display technologies for a consumer to pick from, and here they are:

- Projection: CRT, LCD, DLP, LCoS (the last 3 are called micro displays)
- Tube TV
- Flat panel: Plasma & LCD flat panel
- Front projection (e.g., with screen on wall)

Now, let's go into some detail about the different options…

CRT (Cathode Ray Tube): This is a regular old tube television. A lot of people still feel these TV's have a superior picture quality relative to any other TV on the market. They work by scanning a picture using an electron gun onto a glass screen. The downside is that they're typically so heavy and so deep that they're a big turnoff for many people.

CRT (Cathode Ray Tube) projection: This is large version of a tube TV. Three CRT projection lenses create a picture separately and then the 3 images are “converged” onto a mirror on the back of the TV and then the mirror reflects and projects the image onto a screen on the front of the TV. This TV offers the largest screen size for the least amount of money. This is quickly becoming an obsolete format but there are still some pretty good deals to be had.

DLP (Digital Light Processing) projection: Instead of using a three CRT projection system, the image is created with a halogen light bulb and a computer microchip with mirrors on it. The light bulb shines through a spinning color wheel and a couple of focusing lenses and then the light reflects off of a microchip with an array of very small mirrors on it.

The advantage of this over a CRT projection is that it's much thinner and lighter, and has better viewing angles off to the side. The light bulb needs to be replaced every couple of years. (3-6 years, depending on usage). Reflecting light off the chip gives you a superior black level and contrast over an LCD rear projection.

Here's how they work:

- http://www.dlptvreview.com/dlptv-howworks.html


LCD (Liquid Crystal Display) projection: slightly different from a DLP projection, these also use a halogen lamp but what's different from a DLP is that an LCD will not reflect light, but rather transmit light through an LCD panel. There are three separate LCD panels (RGB primary colors), which typically leads to superior color accuracy (or grayscale) compared to a DLP. However, since the light is being transmitted through an LCD panel, the black is not a true black because the light is always on.

LCoS (Liquid Crystal on Silicon) projection: This TV operates by reflecting light off of three separate LCD-type panels. It's being positioned in the market as a “best of both worlds” solution, taking the better aspects of both LCD and DLP technology. It's supposed to have the superior black level and contrast of a DLP (because it's reflecting light), and the superior color accuracy of an LCD (because of the 3 silicon chips).

Plasma TV: We almost need a separate section just for plasma TV. They work on the same principle as a neon light: there is a sealed container with gas in it and an electrical signal runs through it to excite the gas and change it into a different color. These TVs have a very bright picture with good viewing angles and very rich colors. However, they are, like LCD and DLP televisions, a “fixed pixel display”. This means that no matter what the incoming signal is (DVD, television, HDTV, VCR) they always display the same amount of pixels, or dots, on the screen. What this translates to is that whatever your incoming signal is, the television will either add or subtract information (color, detail, shading, etc etc) to make the image display on the TV.

Two myths about plasma that we need to address right away:

1. They will last longer than 3-5 years
2. The risk of an image burning in is vastly overstated.

Current research says to expect about 60,000 hours out of a plasma television before it reaches half of its original brightness. This equates to about 8 hours / day for 20 years. You will probably buy a new TV before a plasma wears out.

Yes Virginia, there is a burn in on plasma TV, but no, the way you and I and most people watch TV, it's not likely to happen. Here's why: “Burn in” is the result of having one image stay on the plasma screen for quite a long time. (Usually 6 or 8 or 10 hours, depending on the brand). Most people do not watch the same thing on the screen for more than 6 minutes, let alone 6 hours. Think about it, when you watch TV, do you change channels occasionally, or do you literally leave it on the same channel for 10 hours straight? I don't.

Here's how they work:

- http://www.displayhaven.com/plasma.php


LCD (Liquid Crystal Display): Another type of flat panel TV. This TV differs from a plasma TV in that the image, instead of being created by a gas changing color due to electricity being applied to it, is created by running an electrical charge through a layer of crystals that respond and change their orientation and thus their opaqueness to either transmit or block light. In most cases, there is anywhere from one to several rows of light bulbs (anywhere from 8 to 24 bulbs, depending on the size) that create the light behind the TV.

An LCD, as compared to a plasma flat panel, will generally be more expensive, but will use less power and run cooler. It will also have more detail on the picture due to its higher pixel count on the screen. (Generally either 1366 x 768 or 1920 x 1080 for the larger panels). However, the picture will sometimes appear “flatter” and have somewhat of a haze over it, especially as you stand off to the side of it.

Here's how it works:

- http://electronics.howstuffworks.com/lcd.htm/printable
- http://www.viewsonic.com/products/lcd101_howlcdswork.htm


Front Projection: This is the type that will project a very large image onto a wall, typically using a screen in order to increase the perceived brightness and clarity of the picture. These are not televisions; they are only display devices, or “monitors” for other components. They are typically combined together as part of a complete surround sound installation. A lot of planning is required when installing a projector system, with wiring being the most complicated part of it. Another important point is that you need a pretty dark room, otherwise the image will tend to get washed out.

There are many types of projectors, with LCD, DLP, and CRT being the majority of these. (See previous explanations for technical info). With front projectors, DLP's tend to be the brightest and handle ambient room light the best, while LCD projectors generally have a higher resolution (display more detail) and are a little bit more color accurate (skin tones, fine details, etc, etc.)

Here is a general overview of many projection TV technologies:

- http://electronics.howstuffworks.com/projection-tv.htm/printable
- http://www.projectorpeople.com/tutorials/display-def.asp
- http://www.projectorcentral.com


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Now, what TV should I buy and why?

Well, here's where it gets tricky. You're getting into the realm of opinion here. The first thing you need to know about buying a TV now is that there's no right answer to “what's the best TV?” It really depends on what you're looking for.

The first question I normally ask my customers is “What screen size are you looking for?” (Anything bigger than 36” rules out a tube TV)

Next: Do you want to hang it on a wall?
- Yes: either plasma or LCD flat panel
- No: I would probably recommend a CRT rear projection for price point or a microdisplay for picture performance, future compatibility, and future technology (i.e., non-obsolete, whatever that means nowadays)

On the wall: plasma is cheaper, with a brighter picture than LCD, but will tend to use more power and run a little bit hotter. Turning down the contrast setting in the menu will tend to reduce power consumption. LCD will have more detail, handle ambient room light better (i.e., less glare) but tend to have a lag on the picture if it's sports or something else fast moving. One is not better than the other, it's really just personal preference.

Projection TV: Go with a CRT projection if you want the biggest screen for the money. These are quickly becoming obsolete (not to use, but to manufacture, due to declining profitability). The differences between LCD, DLP, and LCoS (or SxRD) rear projection are debatable; again you're getting into the realm of opinion here.

Here are some great websites to explain the differences:
- Choosing a TV (video) http://home.about.com/z/cg/vp.htm?ch=gadgets&l=gadgets/v/10&ap=1
- Myths: http://tv.about.com/od/cableandsatellitetv/a/digitalmyths.htm
- Factors to consider when buying: http://hometheater.about.com/od/televisionbasics/a/buyingatv.htm


BUYING ONLINE

Wow, we could spend days and pages on this one. Buying a TV online basically comes down to this: Do you want the lowest price or do you want the best service?

Unfortunately, in many cases, that's what it comes down to. Why is this, you ask? Well, it's easy to put together a website and advertise a TV at a low price. It's not easy to build a store, build a warehouse, carry the right mix of inventory, develop relationships and networks of vendors, other suppliers, repair shops, and hire and train knowledgeable salespeople. So please understand that there may be vast differences in prices between what you search for on the internet and what you may find in your local store. A good retailer will earn their money, so please pay them whatever they're worth.

Now, having said that, you do have your retailers who are incompetent, abusive, and have no business being in business. Please feel free to eat their lunch in negotiations. I know I do. If you're technically competent enough do figure out all the technologies and hookups, by all means consider buying online. Just be aware that some websites are not authorized dealers for certain brands.


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*** This is the end of the television section. I will now accept critiques from y'all. ***

Dougaha
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