The Miller Channel

By Kevin Miller

Once upon a time in America there was only one type of TV one could buy. It was the old tried and true direct-view tube, a CRT (Cathode Ray Tube) based display device. Thanks to what some are calling the "Digital Revolution" there are now several new promising display technologies vying for your hard earned dough. LCD (Liquid Crystal Display) has been around now for about a decade. Relative new comers to the display game include: DLP (Digital Light Processing) based on Texas Instruments DMD (Digital Micro Mirror Device) and new innovations on LCD technology namely: LCOS (Liquid Crystal on Silicon) and DILA (Digital Image Light Amplifier). Finally, the long awaited and very hot category of Plasma TV is finally starting to come into its own in terms of improved picture quality, and a wider variety of screen sizes to choose from.

The categories I will be looking at are 40 inches or less, which generally speaking are all direct-view tube type TVs with the exception of a couple of odd Plasma and rear-projection models, and greater than 40 inches, which encompasses all rear-projection sets, Plasma TVs and two-piece front projection systems in all display types. I'll be touching on certain features and connectivity options that you should be looking for with the different display types.

27 to 40-inch Displays

Generally speaking 27 to 40-inch diagonal screen sizes will be direct-view displays with the exception of one 40-inch rear-projector. 27-inch direct-views are still predominantly the older analog type, and are still available from virtually all the major TV manufacturers. Samsung is the only company I know of that will be introducing an HDTV-ready 4:3 aspect ratio 27-inch model as of the fourth quarter of 2001.

If you want to get a semblance of the home theater experience a 27-inch screen size is the smallest you should consider. If you are going to use it with DVD you may want to look for a model with component video inputs so you can take advantage of DVD's component video capabilities, which include slightly better resolution and much more saturated and rich color. As a minimum you should look for a model with at least one S-Video input and preferably two or more. For better picture quality from composite and S-Video sources like VHS, Laser disc, cable TV and DBS (Direct Broadcast Satellite) pay attention to the comb filter in the set. Steer away from sets that have Notch filters as they truncate the already limited horizontal resolution of small direct-view tubes in order to reduce NTSC artifacts like dot crawl and chrominance to luminance delay. The four best types of comb filters to look for in ascending order are 2-line digital, 2-line adaptive, 3-line digital and the king of the category, 3D-YC comb filters. A good comb filter will help reduce the above-mentioned NTSC artifacts, and give you a sharper better picture on all your NTSC sources.

Another desirable feature to look for is independent video input memories so you can change the various picture parameter levels for different sources, thereby enabling you to optimize all your video sources. This is still a rare feature in small direct-view sets, but one worth looking for if you can find it.

In the 32 to 40-inch category of direct-views there is a great deal to choose from depending on what you are looking for. Inexpensive analog only 32-inch direct-views start at around $500, and there are now 32 and 36-inch 4:3 HDTV-ready sets hitting the market that will enable you to watch HDTV broadcasts, although not at their full resolution. 4:3 HDTV-ready 32 and 36-inch sets start at about $1299 and go all the way up to $2500. Widescreen digital HDTV capable direct-views are available in 30 and 34-inch screen sizes with the 34-inch category offering the most choices. Prices range from $1899 to $7500.

If your opting for an analog set check the horizontal resolution spec, and make sure that it is at least 480 lines. This way you'll know it can fully resolve DVDs, which will be the highest resolution source you'll be able to feed into it. Direct-view sets rarely exceed 480 lines of horizontal resolution, although some widescreen models do. If you are buying a widescreen HDTV-capable model you'll want to pay attention to this spec as well. Generally speaking the higher the number the better, but be careful not to sacrifice other important features for a set with only slightly higher resolution.

With HDTV-ready sets the video processing (line doubling etc.) becomes an important part of the purchase decision. Let's face it as much as we all want HDTV it isn't happening at breakneck speed, and we'll be watching NTSC sources like DBS and DVD for a long time to come. Some of these big screen direct-views (most of the widescreen models) offer broadband component video inputs that will allow you to put a higher quality outboard video processor on it to improve NTSC video performance. Look for models with two broadband component video inputs so that you won't need a component video switcher to accommodate both the line doubler or a progressive-scan DVD player and an HDTV set-top box.

Currently the only 40-inch direct-view available is the Sony KV-40XBR700, which is an HDTV-ready set, and now incorporates the all important 3:2 pull-down circuitry in the set's DRC (Digital Reality Creation) video processing. It offers a very cool feature with a Multi-Image Driver, which allows you to watch an NTSC and HDTV broadcast simultaneously side by side. The 40XBR700 will carry a list price of $3499 down from its original projected price of $3999.

The only 40-inch rear-projector currently available is the Toshiba 40H80 a 16:9 aspect ratio set with 7-inch CRTs that carries a list price of $2999. It has a claimed horizontal resolution of 1280 lines, two broadband component video inputs, relatively good line doubling circuitry, and an excellent color decoder. The set also offers independent input memories and a universal remote control.

 

Greater than 40-inches: rear-projection, Plasma and two-piece front projection systems

Rear-projection:

Currently screen sizes for RPTVs range from 40 to 80-inches. While CRT based RPTVs still predominate, new solid- state technologies are beginning to make inroads into the category. LCD, LCOS, DLP and DILA based RPTVs are all beginning to hit the market. Currently none of them can compete with the CRT based sets in terms of picture quality, and all of these new fangled sets are still very pricey.

One of the biggest differences between rear-projection displays and direct-view, particularly CRT based RPTVs, is that they are not capable of being nearly as bright. Therefore, some attention needs to be paid to light control in the room if you want an RPTV to look its best. As with any display device setting the contrast and brightness properly is essential to achieving a good picture. You can do this yourself relatively easily by using the test patterns on either the AVIA or Video Essentials DVD.

Another factor to bear in mind with CRT based RPTVs is convergence. On a CRT based RPTV there are Red, Green, and Blue CRTs (Cathode Ray Tubes) that converge together to make the picture. The tubes need to be aligned properly to obtain the sharpest picture possible. Unfortunately shipping often throws this critical parameter off significantly. The good news is most new generation HDTV-ready RPTVs have multiple point convergence in the user menu so you can tweak it yourself. Convergence also drifts over time, and therefore needs to be adjusted periodically.

Analog CRT based RPTVs can be had for a song these days as most manufacturers are beginning to wean them out of their lines in favor of digital HDTV-capable sets. HDTV-ready sets range in price from as low as $2000 for Panasonic's new 47-inch model to nearly $10,000 for some of the rare sets employing 9-inch CRTs. CRT based RPTVs employ either 7-inch or 9-inch CRTs. The 7-inch CRT is the most common, but 9-inch CRTs are capable of displaying much more resolution from HDTV sources.

All the major TV set makers are getting into solid-state fixed pixel RPTV production. Some are opting for LCD or LCOS based technology, several are going with DLP based rear screen models, and JVC has opted for DILA, a form of LCOS based on their relatively new front projection systems. One of the main advantages of fixed pixel RPTVs is that convergence is fixed from the factory and will never drift like a CRT based unit. The other big advantage of fixed pixel displays over CRT is that they are capable of producing much brighter pictures. Most of these sets can be viewed with some ambient light in the room without looking washed out as a CRT would. Finally, instead of costly tube replacement on a CRT, a fixed pixel RPTV whether LCD, DLP or DILA needs only a light bulb replacement, which in most cases can be done by the end user. Cost on replacement bulbs range on RPTVs from about $300 to $600 depending upon the manufacturer.


There are a couple of distinct disadvantages in solid-state RPTV display technologies that you should consider before making your purchase decision. Perhaps the biggest disadvantage of all fixed pixel displays is black level performance, or the ability to discern detail in dimly lit scenes, which is not nearly as good as with CRT based RPTVs. Color accuracy is also not as good.

Finally, these types of displays are currently much more expensive than similarly sized CRT based sets. They range in price from $7995 for RCA's new LC50000 LCOS based 50-inch RPTV to $14,995 for Mitsubishi's 65-inch 1-chip DLP based RPTV. All these sets have state-of-the-art 3D-YC comb filters, all the connectivity options you could possibly require, and a host of convenience features like 2-tuner PIP and the like. The DLP and LCOS based displays all have native fixed resolutions of 1280 x 720, and the JVC D'alia sports a slightly higher native resolution of 1280 x 1024.

Plasma Displays

Plasma is a relative new comer in the display arena. They are also a fixed pixel design, and offer many of the same advantages and disadvantages as fixed pixel front and rear-projection sets. That is they are capable of producing very bright pictures, and consequently are good for use in high ambient light conditions. In this regard they are very similar to direct-view TVs. They are also extremely thin and wall mountable giving them great flexibility for integration into a multitude of different rooms/viewing environments.

Most of them also suffer from poor black levels, and poor color fidelity. There is another problem specific to Plasma called "false contouring", which manifests itself in low light scenes as moving patches of artifacts. With most panels the weakest link is the built-in video scaler, which must convert all signals to the panel's native resolution. For this reason I recommend you mate a plasma with a good outboard video processor or scalar that offers a scan rate compatible with the panel.

Plasmas originally came out in a 42-inch diagonal screen size, but now screen sizes range from 42 to 61-inches. Generally speaking the 42-inch panels have a native resolution of 852 x 480, which is ideal for 480p sources. There are a couple of 42-inch models out there with 1024 x 1024 resolution, but don't be fooled by the numbers as some of the lower res panels actually produce better pictures. 42-inch panels range in price from about $7995 to $12,000.

The 50-inch size category is where true HDTV capability starts with plasma technology. Virtually all the 50-inch panels, and most of the 60 and 61-inch models have native resolutions of 1365 x 768, which is more than enough to fully resolve a 720p HDTV source. Prices range for 50 to 61-inch plasma panels from about $15,000 to $32,000 for the bigger screen sizes.

Connectivity on these is usually fairly comprehensive. RGBHV connections using BNC connectors is very common. Some panels even use a BNC connector for the composite and the component inputs, which means you'll need RCA to BNC adaptors to hookup most HDTV set-top boxes and DVD players. Plasma panels for the most part are monitors without internal amplifiers and built-in speakers, and as such they lack many of the consumer features typically found on rear-projectors and direct-view sets.

Two-piece Front Projection Systems

For a truly big screen home theater experience two-piece front projection systems are the way to go. The same display technologies in rear-projection are available in two-piece front projection systems. Generally speaking the same advantages and disadvantages apply to front projectors.

CRT based front projectors come in three flavors: 7-inch CRTs (the most common and the most affordable), 8-inch CRTs and 9-inch CRTs. The larger the CRT the more resolution they are capable of displaying. Some manufacturers now package their CRT projectors with a video processor or scaler, but for the most part you'll need to choose a good processor to mate with a front projection system to optimize your NTSC video sources.

If you want the best possible picture quality CRT is still the reigning champion in that regard, but it does come at a price. Some of the disadvantages include: the necessity for complete light control due to low light output, and hiring a qualified installer for the installation, initial set-up, and ongoing maintenance of the picture (another cost consideration). They are also relatively expensive when compared to fixed pixel projectors. 7-inch CRT machines now range in price from about $8000 to $18,000, 8-inchers from about $14,000 to $32,000, and the big gun 9-inchers from $35,000 to $60,000. Sony is the only mass-market video company that offers such beasts. Lesser-known companies that have been specializing in this rarified product category include: Runco International, Vidikron, Seleco and DWIN.

Solid-state front projection systems now offer a wide variety to choose from, where not long ago the LCD projector was the only choice. They are in general much less expensive, very easy to set-up and maintain, and less prone to breakdown. However, all these positives also come at a price: picture quality is not nearly as good as with CRT based units. As mentioned earlier in the RPTV section the fixed pixel displays have black level and color fidelity problems. The DLP technology so far looks the most promising to me in the front projection arena.

Consumer level 1-chip DLP projectors come in three different resolutions: 800 x 600, 1024 x 768, and 1280 x 720. Sharp's XVZ9000 is currently the only high-resolution 1280 x 720 1-chip DLP projector, but you can bet all the other DLP projector manufacturers will soon have similar models. In my opinion DLP projectors produce superior pictures over LCD based units for several reasons. Firstly, what we call the "Fill Factor" or the space between the tiny micro mirrors in a DLP chip is much smaller than it is between the pixels of an LCD panel. This is one reason why even a lower resolution 1-chip DLP projector can look better than a much higher resolution 3-panel LCD unit. DLP also has slightly better black level performance over traditional transmissive LCD, and finally the color fidelity is better.

DILA technology an innovation on LCOS (Liquid Crystal on Silicon) is also promising from a picture quality standpoint. JVC has developed this technology, and at least one company has done some impressive modifications to the chassis that enhance its performance for home theater use. The Madrigal MDP-1 has made strides in improving the gray scale performance of the DILA, but the internal scaling is poor, which makes it absolutely necessary to add an outboard video processor or scaler for the best results. Relative to 1-chip DLP and LCD projectors it is expensive though, carrying a list price of $26,000. HDTV-ready LCD projectors start at about $8000 and go up to around $20,000. The 1-chip DLP projectors that are HDTV-ready start at about $10,000 and go up to about $17,000. 

The video processor or scaler is an extremely important factor in obtaining the best picture quality of any front projector with NTSC video sources. Most of the internal scalers in fixed pixel devices are quite poor. Of course, in the case of a CRT based unit HDTV sources do not get processed, but rather are sent directly to the projector for display on the screen. With fixed pixel projectors all signals are scaled either up or down to exactly match the panel's or chip's native resolution. The screen you choose is also an important factor in the overall video performance of any type of projector.

Front projectors, much like plasma panels are monitors, and therefore have virtually no consumer features. They do offer the most movie theater-like experience, though. For the best experience with a front projection system, no matter what type of projector you opt for, be sure to do your home work on the screen material best suited for the display technology, and the optimum screen size for the device and the size room your planning on putting the system in.

In fact, no matter what category of TV you're looking for to improve your home theater experience you should carefully consider what you want to achieve, the room you are going to put it in, and the features that you want from it before making the plunge.

Regularly posted columns and articles related to video and/or home theater. These will not only be product related, but also tutorial in nature, intended to offer advice or guidelines for home theater setup. In some cases The Miller Channel will discuss video and/or display related technologies if something new and noteworthy comes to light.
Display Types and Technologies
10/11/01

(from Home Theater Buyer's Guide Fall 2001)

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