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First of all, don’t assume you need a huge video screen in your media room. If your screen is too large, visual fatigue will detract from your theater experience. A good, but general rule for screen size is to select a screen width that is half to one third the distance from the screen to the primary viewing location. You should keep the viewing cone, formed by a line going from your eyes to each side of the screen, to about thirty degrees.

You can use any display device and there advantages and disadvantages to each type. DLP units tend to have better black levels than LCD units. LCOS units and variations have the tightest pixel structure.

Front Projection:

Advantages

A front projection set will produce the largest, most dynamic image. With a good projector and screen combination the image will be quite stunning, especially when watching native HDTV content. If you have never seen the picture produced by a good, front projection set up, you really should see one before you make any decisions.

Disadvantages:

Needs ambient light control. You need to control ambient light to get a really good picture because a front projection system cannot produce black. It must rely on the absence of light being reflected from the screen to show black or dark colors.

You have to have a physical projector mounted somewhere. This problem has improved tremendously in the last few years as CRT projectors have basically gone away and digital projectors have improved and shrunk to miniscule proportions.

Video projectors are noisy. They require cooling fans and these are loud. Some recent units however, are much quieter.

The larger picture and better detail reproduction will allow you to really see problems so you need to have quality video sources or the picture will suffer.

Many of the projectors on the market are either business presentation units or adapted from them. Business presentation projectors have much different requirements than home theater projectors. The most important requirement for business units is brightness. They sacrifice other performance parameters to achieve this. Home theater projectors need extremely accurate color rendition, accurate grey scale tracking, deep blacks, and freedom from motion artifacts.

Plasma:

Advantages

They’re thin! Only 3 to 4 inches thick.

They look great when displaying HDTV. (most of them)

Disadvantages

They can suffer image burn-in when displaying static images. Many retailers and manufactures downplay the dangers, but the phenomenon occurs with many different units. Do not leave the cable or DSS menu screen up for an hour or two. Be careful when displaying HTPC or computer game video with static images.

Many of them look really bad when displaying non HD TV. This problem has lessened with improved internal video processing and scaling technology. Some plasmas actually look pretty good with a better quality DVD feed.

Many plasmas suffer from rather severe image artifacts although this is also improving greatly due to the better internal processing.

Some plasma displays have high power consumption. (Can be three times that of a standard tube TV)

LCD flat panel:

Advantages

They’re thin! Some are only three inches thick.

They have no image burn problems like plasmas do.

Good picture on most newer sets.

Long life (50,000 - 60,000 hours)

You can get a true, 1080P native resolution display.

Disadvantages

Sizes over 30 inches are priced above equivalent sized plasma displays.

The older units don’t have picture quality as good as plasma displays.

Black and dark reproduction is not as good as plasma yet.

Rear Projection TV can be either digital or CRT based. The CRT units are going away fast as consumers move to thinner, lighter digital rear projection TVs. At this point, the better CRT rear projection sets offer fantastic performance for the money. You can get a 50+” HDTV ready CRT set from good companies such as Panasonic and Sony for under $1,500. These bargains will be gone soon as production of CRT rear projection sets stops. Panasonic has indicated the 2005 model year will be their last for CRT RPTVs.

The disadvantage to CRT rear projection TVs is size and weight. They too will suffer image burn problems if left with a static image for too long. They require accurate convergence to look their best. Most newer units offer multi-point convergence adjustments to facilitate this.

There are some new types of flat panel displays that will be released for consumer use soon including Organic Light Emitting Diode (OLED) and SED. These promise even better image quality than either LCD or plasma when fully developed, in addition to lower cost, thinner profiles and much lower power consumption.

In a nutshell:

Front Projection - Large image, can have spectacular picture quality even on a huge screen - More difficult to set up, need to place the projector in the center of the room somewhere, noisy(some), must use better quality sources to get the most benefit.

Plasma - cool factor, thin, look good for HDTV - Image burn problems, can sometimes have a mediocre picture for all but HDTV sources

LCD - cool factor, thin, look good for HDTV, no Image burn problems, - Expensive for larger sizes, can sometimes have a mediocre picture for all but HDTV sources.

There are many display technologies available today. No one display is best for all situations. Select the one that best fits your select your specific requirements.

Steve Faber has almost 15 years in the custom installation industry. He is a CEDIA certified designer and Installer 2 with certifications from both the ISF and THX. His experience spans many facets of the industry, from the trenches as an installer and control systems programmer, and system designer, to a business unit director for a specialty importer of high end audio video equipment, a sales rep for a large, regional consumer electronics distributor, and principal of a $1.5M+ custom installation firm. Steve is currently is senior sales engineer for Digital Cinema Design, a CEDIA member firm in Redmond, WA. See more great information about choosing the video display for your home theater and more at: Home Theater Video

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So, you’ve been bitten by the home theater bug, eh? You want to design your own home theater but are unsure about how to do it? Here are some quick tips on how to design you very own home theater. First, there are some basic questions you must answer.

1)How much space are you working with, or, alternatively, if you are building a room from scratch, how many people would you like to seat in your home theater? If using an existing room, what shape is it. Is it a closed room or is it open to the rest of the home? Where is the door in relation to the rest of the room? Would you like true theater type seating or will you be using sofas and love seats?

2)Will it be a multi-use room or a dedicated theater? If you are using the room for multiple purposes, you will need to be more careful about hiding components to integrate the theater with the rest of the room. Layout will become extremely important so you can maximize the use of the available space.

3)What is your home theater budget?- If you are fairly new to the game, you may not have a good idea about a realistic budget, so do some research on material and equipment costs.

4)What kind of d

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You’ve all heard it, that dreaded 60Hz hum through the speakers of a home theater or house audio system. Hopefully you heard it at a friend’s house and not your own. It can drive you completely nuts. You may have even tried, unsuccessfully, to fix the little noise problem. That can make you even more crazy. What causes that horrendous noise through your speakers?

More often than not humming through your speakers is caused by a grounding problem. There are three main ground problems that cause problems in an audio / video system. These are ground loops, improper grounding and lack of a ground altogether. The other possible culprits that can cause noise are bad cables, a faulty piece of equipment or electrical noise from a lighting dimmer or electric motor. There are steps you can take to troubleshoot the noise and eliminate it from you theater.

The first step is find out where it is coming from. Disconnect your source and display equipment from your receiver or surround sound processor. If the noise stops, connect them back to the receiver or processor on at a time until the noise returns. When the hum comes back, you found where the noise is entering your system. Note that if you are connecting remote equipment, such as running the signal from your theater room DVD player to the TV in the bedroom, your chances to pick up noise increase dramatically. With such long runs, noise can be induced into the long cable runs from adjacent electrical wiring. It is also easy to create a ground loop, because the equipment is plugged into two different, widely separated outlets, on different electrical circuits.

If the noise is caused by a cable box, the noise is likely caused by the cable TV ground. To test this theory, disconnect the incoming cable TV feed to the rear of the cable box or TV while they are still connected to the rest of the system. If the noise is eliminated by disconnecting the TV cable, the problem is the cable TV ground. You can electrically decouple the cable TV feed from your system with a ground breaking transformer. These are available from many sources. Be advised that many newer, digital cable TV systems require any device in the signal chain to pass a full 1,000 Mhz. Some of the older ground break transformers will not do this. Be sure to check the specifications of whatever device you are purchasing to verify it will pass the digital cable TV signal.

If the noise is from your projector, TV, or monitor, it is most likely caused because the video display device is plugged into a different outlet than the other a/v equipment. It could be on a different circuit as well. These circuits may have two different ground potentials. That is, the resistance to ground is different on each circuit. A difference in resistance to ground from one ground point to another can cause the dreaded ground loop. If you get a ground loop, current flows between the two components. If the current flows through the components internal audio signal ground, you will get a hum.

You can use an isolation transformer, similar to the type used for cable TV ground problems, to eliminate the electrical connection from one component to the other. These transformers are inserted in line with the audio signal connection between the two components. If there is no audio connection between the components, the problem may be current flowing through the video portion. In this case, a video isolation transformer should be used to eliminate the ground loop.

Sometimes power conditioners will stop noise problems by placing equipment on different, electrically isolated outlets. This is done using isolation transformers. Sometimes this is ineffective however, due to the differences in internal construction of different power conditioning equipment. Some safety regulations, such as UL 1950, specify that an isolation transformer is only allowed to isolate the hot and neutral wires; the grounding wire must be passed straight through. If this is the case, the ground loop problem may still exist because many communication circuits are connected to the grounding conductor and not the neutral. In this case, the isolation transformer, or any power conditioner or UPS with an isolation transformer will have absolutely no affect on the grounding problem.

The noise may be generated externally, from a dimmer or refrigerator compressor for example, and coming in through the main power input on the audio video equipment. In this case, a high quality power conditioner may be effective in reducing or eliminating the noise problem. You may also find that one of the signal interconnecting cables in your system is faulty. This can also cause noise problems. Check for this by swapping the cables with one that you know to be good.

You can solve most noise problems in your home theater or multi room audio/video system by taking the systematic, step-by-step approach. Work your way up the signal chain, eliminating each piece of equipment as you go. If you have nothing connected to your speakers except the speaker wiring, and they still hum, the problem is noise induced into the speaker wiring from adjacent power cables. Other than that case, most problems are caused by ground problems, which you can find, and solve, if you take it one step at a time.

Steve has 15 yrs in the consumer electronics industry. He is a CEDIA certified designer with ISF and THX certificates. His experience includes: installer and programmer; system designer; business unit director for an a/v importer; sales rep for a CE distributor; and principal of a $1.5M+ CEDIA firm. He’s now senior sales engineer for Digital Cinema Design in Redmond, WA. For more information on how to make your home theater better, and what’s on the horizon, including CEDIA and CES show reports, see The Home Theater and Automation Guide

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