CREATING EXCITEMENT
Aug 1, 1998 12:00 PM, Bob Heil
Little can compare to the feeling and excitement generated by attending a live event-albeit a music concert, boxing match or baseball game. The experience is sensational. When discussing a home theatre system, it is agreed that a similar feeling (or part of that live experience) can be recaptured by projecting the video image onto a large screen and reproducing the audio through a multi-channel Dolby sound system. By assembling the right equipment and installing it in the correct space, one can have an impressive home theatre system, even at a reasonable price. Many consumers have been misled by dealers whose motto seems to be, "the more you spend, the better it looks or sounds." How terribly wrong. Ego has done a lot to ruin many potentially wonderful media rooms. And so we have to trundle through the pile of rumors, rubbish and myths to create an affordable home theatre system.
The first step is to choose the best space. Room dimensions are crucial for good sound reproduction. It is always better to have a rectangular room with an approximate height, width and length ratio of 1.0 to 1.6 to 2.5. Because most homes have an 8 foot (2.4 m) ceiling, an appropriate media room would be 13 feet (4 m) wide by 20 feet (6.1 m) long, and if this is new construction, the walls should not be parallel. They should be slanted by several degrees to help reduce the standing waves.
Sound does not simply emit from the front wall to the back wall and stop. It reflects 90degrees off the back wall and hits the floor, ceiling and side walls simultaneously, thereby creating all kinds of reflective sound patterns. Because sound travels at 1,120 feet (341 m) per second, this can certainly create some pretty mean phase cancellation, all of which results in slight echoes and hollow-sounding audio. The solution is simple. Kick the top of the wall in about three or four inches (76 or 102 mm). Curve the ceiling a bit. Ever notice a high-dollar recording studio? None of the walls are ever parallel. They were not built like that for purely modern visual appeal; they are designed deliberately to help reduce the standing waves, and it is so simple to do. A good interior designer can take that and get really creative with matching swirls and curves in the carpets, furniture and wall coverings.
A quick point about wall coverings. The best wall coverings for a great sounding media room come from covering the virgin wall board with cotton, which, in turn, is then covered with satin or similar material. This practice creates a great look and virtually eliminates reflective sound patterns, all for very little money.
Front or rear projection Upon defining the space, the major equipment decision will be the type and size of the video image. The easiest (and usually least expensive) will be a rear-projection television. There seems to be a glut on the market today of the 40 to 60 inch (1,016 mm to 1,524 mm) varieties with several late comers out to 70 and 80 inches (1,778 mm to 2,032 mm). The caveat here, however, is that many of these do not exhibit the most pristine video images. As I said earlier, bigger and more expensive does not always equate to the best. There are some exquisite rear project TV items lately, but you are going to have to hunt for the specialty custom and industrial dealers that carry the likes of Hitachi's new SBX and such reference monitors as the Pioneer ELITE. These are excellent rear-projection display devices, and they would serve as an adequate centerpiece around which to design and build your room.
The alternative is a front-projection unit. In the past decades, the three-gun analog projectors from Ampro, Runco, Zenith and Sony were quite well accepted; however there have been a number of terrific breakthroughs coming from Sharp, Ampro and others giving us LCD (liquid crystal display) projectors that are more than capable of filling the role. They are lighter, need little service (no lens convergence) and are relatively inexpensive (starting below $3,000). All can rise to the task of producing beautiful video images on screen sizes up to 15 feet (4.6 m).
An interesting approach to the design of the room is to place the projector behind the screen. The throw distance of usually about 12 feet (3.7 m) is still needed, but using a special membrane-type screen that can be projected through (instead of a front projection screen upon which images are projected) can allow the projector to be moved out of sight. A great example of this is shown in the August 1997 issue of S&VC on page 16. Mounting a projector behind the screen can give the designer tremendous latitude, help cut down on ambient light refractions and provide a stunning, bright image on the screen with all focus on the picture and not the projector blaring its beam of light across the room.
Keep in mind that any of the front projection systems are not usable in high ambient light, so if you have lots of windows in the media room, some method of motorized drapes or blinds will be needed to darken the room if used during the daylight hours. If this will be a multi-purpose room rather than a dedicated media or home theatre room, it would be advisable to look in to the 50 or 60 inch (1,270 mm or 1,524 mm) Elite rear project television monitor or similar product instead of a projector and screen.
Loudspeaker placement In this case, we actually are dealing with firm science. No questions about that, but so many of the systems seen today just seem to forget that, Worse, many even attempt to defy it, and, of course, it shows in the poor quality of many home-theatre systems, regardless of their expense. Loudspeaker placement is crucial to the faithful reproduction of the dialog sound, the music and the special effects. Even the sharpest video image will not alleviate poorly planned loudspeaker placement, especially if the audience is incapable of understanding the dialogue.
Front left and right speakers should be placed at ear level when seated. No higher. Anything less than six feet (1.8 m) between these two will not give a wide enough front spread while 10 (3 m) feet or greater loses the whole front image. It has been proven that in the home systems with a 15 foot (4.6 m) wide by 20 foot (6.1m) long room, eight to 10 feet (2.4 m to 3 m) is a perfect spread from the fronts with the center channel being in the center either above or below the screen.
With either front or rear projection, it is best to dedicate one wall for the screen and front line of loudspeakers. There are two schools of thoughts about this wall. Some like to have just the screen and loudspeakers with no distraction from anything else while others like to see the equipment racks on either side of the screen.
Moreover, the ideal subwoofer setup is to use two of them-one under the left and one under the right front loudspeakers. The subwoofer must be self powered with a parametric crossover so you can change the parameters for each room in which it operates. The frequency, the roll-off and the level is a must for proper subwoofers. The big caveat with all subs is that if it does not have a built-in power amp (or dedicated amp just for that sub) walk away from it. Your client should have no place for toys in his new home theatre.
If only we could devote this entire month's issue to this subject of surround loudspeakers and their proper placement, but even then, we would probably still have things to learn. First off, surrounds do just that. They are intended to surround their audience with ambience. Normally, this is evident through such effects as crickets wind blowing, but it they are intended only for effects. You will never (well maybe for a simple effect in somebody's movie script) hear a leading role's voice speaking through one of these loudspeakers. You will not hear a flute in the right, guitar in the left front, dialog in the center and piano in the rear. An important note, so read closely. Ray Dolby's wonderful Pro Logic technology is not the same as old QUAD system. It is truly a surround effect channel, and it is because of this that we must pay close attention to their placement. Science dictates procedure here.
The ideal is to use Tom Holman's idea of dipole speakers so that we actually receive surround information from the reflections off the screen and rear wall. NEVER anything coming into the room directly from the surround loudspeakers. The best in-wall or simple on-the-wall (picture hung type boxes) placement involves placing them on the side walls two to three feet (610 mm to 914 mm) behind the listeners ears and no more. This creates a wonderful sound field with the front line of loudspeakers and enhances any four-channel Pro Logic system. As you can see, all this enhancement requires is just simple and correct loudspeaker placement.
One last item about surrounds. It has always been an industry perception that because Mr. Dolby only gives us 100 Hz to 7,000 Hz in these effect rear channels, there is no low-end response. Well, if you really want to enhance any home-theatre system, place a dedicated powered subwoofer behind the intended audience and connect it to these rear surround loudspeakers. You will be amazed at the results. There is plenty of low-end response back there, enough that at the small expense ($450 to $600) for some wonderful powered subs makes it a must to spec for your room.
Equipment location Last, but certainly the most important, is the equipment itself. The ideal thing to do is mount the equipment into a 19 inch (483 mm) rack and shelf assembly. The entire unit can be placed right in the wall or in a properly sized "hole" of your custom entertainment center,. It is the 70-year-old technology of the telephone industry that allows us to wire, test and align all of the gear and then simply slide it into place without having to get out the dental mirror and lose your religion trying to get behind the equipment to plug something in. Ultimately, the location is your call, and it should be based upon your client's individual tastes and preferences. If he likes to see the flashing LEDs, place the equipment at either side of the screen. Placing the equipment behind the intended seating area will mean that you should install some infrared repeaters so that the user can point the remote at the screen and then send that signal to the equipment behind him.
Connect and enjoy Of course, once all of the hammers are at rest, the paint and glue is dry we only have to connect the wire, which, presumably, was run to the correct locations during construction. After that, it is up to your client to savor the results of your labor. One small note about that wire. Another of the industry rumors is the bigger the better. Time and time again, study after study has been performed, and a Julian Hirsch review of 1994 said it best, "the effect of the huge wires is normally only a minute change in frequency response." This is hardly a matter to be concerned about unless you or your client happen to be the type of person who agonizes about how many angels can dance on the head of a pin. After several thousand audio systems designed and installed, I am still using 16 gauge, not the small stuff but the large lamp cord for runs under 50 feet (15.2 m) and in most of the media rooms, 50 foot cable runs are seldom, if ever, reached.
Intelligent planning and equipment placement, not expensive electronic devices, are critical to the creation of a high-quality media room. Even the most expensive loudspeakers and display devices will perform far short of expectation if their installation is not given due consideration. Follow these simple procedures, and you will go a long way towards satisfying your client, especially if you produce a good home theatre room while also lowering his expenses.
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