Tips From THX: Getting the Most Out of Your Home Theater

tips from thx

THX was founded to make sure that commercial cinemas perform up to certain standards. Since then, the company has expanded that mandate to include home theaters and individual AV products as well. To that end, I asked CTO Scott Francis to outline some basic tips from THX to optimize the location and setup of the display, speakers, and seating in order to get the most out of the entire system, whether it’s just you, your immediate family, or a big party watching movies, TV shows, or sports.

He started with a caveat: “In general, the best setup is the one you enjoy the most and that provides the most enjoyable experience for you and your guests. Don’t be afraid to change something to suit your tastes or ensure your guests can see, hear, and have a good time just because you already have something dialed in to be technically ‘correct.'”

What’s the best location for the display?

“Ideally, you should have a straight-on, nearly level view to the center of the screen from your main viewing position. Ten to 30 degrees off axis horizontally or vertically isn’t a big deal quality-wise, and with modern displays, the viewing angle is much wider to accommodate a party. The room often dictates what is possible here, and you may need to work with seating in terms of arrangement and furniture choices to avoid neck strain or otherwise holding uncomfortable positions for too long.

“This is often a problem with mounting the displays over a fireplace. The display ends up too high for many couches and causes you to look up. However, if you typically watch in a reclined position, this arrangement can be quite comfortable. It may also offer a second row of viewing from stools around a bar or table behind the main viewing position, which is common in many family room/kitchen layouts.

“If you are using a projector instead of a flat-panel display, the viewing angle may more constrained. Find a location that you can see without straining your neck.”

What’s the best location for the speakers?

“Once you’ve anchored the room with the display, speaker placement should be roughly symmetrical around that focal point. Most rooms are not completely symmetrical—they might have only three walls, offset center lines, steps, or other architectural items. A little of this isn’t a big deal, but if you can’t locate the front left, center, and right speakers in a plane at right angles to your sight line with equal distances to the left and right speakers, you may have some odd imaging. It’s worth adjusting the display location in consideration of this if possible.

“The center speaker should be very close to the display—in general, immediately above or below the screen, although behind the screen is an option with projector setups that include an acoustically transparent screen. This may be less of an issue for sports viewing, but for theatrical content, most dialog comes from this location, so keeping the center speaker close to the display will provide a more immersive experience.

“The front left and right speakers should be equidistant from the center as well as from the main viewing position. A bit of offset, say 10-20%, can be compensated for by adjusting the channel delay and gain in the AV receiver, but too much will disrupt the imaging, and you end up hearing the speakers instead of the content. For sports, I find a pretty wide stage and widely separated speakers to be fun. However, more than 30 degrees off axis from the main viewing position can be distracting for theatrical content.

“I’ve seen many people mount their front left and right speakers immediately adjacent to the display. I don’t care for that setup myself. I feel it clamps down the soundstage. For most content, stretching that stage beyond the space of the screen is more pleasing.

“However, if you also use the room for 2-channel listening, separating the front left and right speakers a bit less can be desirable. In particular, if the front left and right speakers are within 15 degrees of the centerline of your seating position, direct sound will dominate. As the angle increases, reflections and indirect sound increase to the point at which you will experience increased levels of crosstalk.

“Surround and height speakers should be mounted symmetrically around the listening position and, most importantly, so you can hear them! I often see people just stick them anywhere or with downfiring ceiling mounts. Consider smaller surrounds that you can mount closer to ear level with a straight path to the listening position. Symmetry in terms of path lengths is probably the most important consideration here.

“In a 5.1 system, you want the surrounds to be somewhat behind the listening position; otherwise, the soundstage can collapse. On the other hand, if they are too far back, the immersive surround effect can be lost. Experiment with positioning in terms of what is possible in your room to decide what shows off your favorite content the best.

“For sports, I like the effect of having the front and rears almost as corners of a box with the viewer in the middle of the back half of the box. To my ears, that provides a very stadium-like feel.

“Subwoofers are easy to position roughly and difficult to position perfectly. You’ve probably heard that bass is omnidirectional and hence placement doesn’t matter. That’s true to a certain extent, but placing the sub off center or in unusual positions can sometimes cause odd delay effects at some viewing positions. Using two subs can clean that up to a large degree, as can experimentation in placement. Finally, delay settings can also help some issues. Given the room’s acoustics, placement closer or farther from a wall or corner can have a great impact. Experiment with placement and content.”

[Editor’s note: According to the THX website, “If you have four subs, place one in the middle of each wall. If you have two, put them in the middle of opposing walls. If you have one, place it in the middle of the front wall.”]

What’s the best location for the seating with respect to the screen and speakers?

“Where you can see and hear clearly! Consider any reflective and absorptive surfaces in room and the acoustic path between the speakers and your ears. Is there a hard wall behind you? Perhaps a painting or tapestry will help tame the reflections from that wall. There should be clean sightlines from your viewing positions to the display and to all speakers.

“Next, consider the ‘throughlines’ from the speakers through your head. What’s on the other side of your head? Is it a wall? Is that wall covered with reflective or absorptive material? What is the angle of reflection? Can the sound bounce in a funny way and create muddiness or boomy room modes? An adjustment in angle, mount, or position might help, as can wall treatments.”

What are the best display settings for watching in lots of ambient light—say, during a sports-watching party?

“Most modern flat-panel displays are plenty bright enough for nearly any indoor condition. However, consider bright windows and doors. It can be very difficult to compensate for a shaft of light directly on the display, so try to avoid that particular situation.

“White points for sports are generally at a higher color temperature with more aggressive gamma curves than theatrical content. A color temperature between 5000 and 6500 degrees Kelvin is probably right for basketball, which is an indoor sport, and that closely matches the illuminant on the court. I wouldn’t recommend going much above 6800°, which will probably look too cool.

“For a party, you’ll probably have lights on in the room, so consider the total brightness as well. It may be worth sacrificing some black level for this—which means increasing the brightness control above its optimum setting—something you normally wouldn’t do for theatrical content.”

What are the best display settings for watching fast action like sports?

“Your display likely has a ‘sports’ preset, and I would use that as a starting point in terms of which settings are best for fast-action sports. These settings are very model-dependent. For example, edge enhancement works well on some units, while on others, it can take a couple frames to ‘settle.’ This may be acceptable for theatrical content, but it’s maddening for sports.

“Many displays can oversample and create ‘tween’ frames using motion prediction; this process is often called frame interpolation. If your display cleanly creates these tween frames, it can create a look that is a bit less ‘crystalline’ and harsh. However, the effect can be very ‘soap opera-ey.’ Some displays will also apply an artificial phosphor-decay envelope to their tween frames to simulate the effect of phosphor decay in CRT and plasma displays, which can be very pleasing.”

What are the best sound settings for watching sports?

“Crank it up! If you’ve followed the setup guidelines discussed here, the broadcast feed should serve you quite well. Most AVRs and preamp-processors offer various effects modes such as ‘stadium’ that generally aren’t necessary for a well set-up system, but if you’ve created an improvised party room, they might just provide some benefit.

“Basketball, in particular, is rich with sharp, percussive highs set wide in space. Some people find all those shoe and ball squeaks to be too much. For them, a slight treble rolloff can smooth out the experience.”

Do you have any other tips pertaining to watching sports versus movies or TV?

“Chips and crunchy items should only be eaten during timeouts; for that reason, we serve tequila-lime grilled shrimp at my house. Don’t throw anything at the screen when the officiating doesn’t go your way, and generally have a good time!”