HT Boot Camp: The Agony and the Ecstasy Page 3

Also, since the distance from the listening position to the center speaker will be different than the distance from the listening position to the left and right speakers, adjust for this with your surround controller, if possible. Most modern controllers allow you to adjust the distance to each speaker in the Loudspeaker Setup menu. Don't guess at the distance to each speaker; use a tape measure. If you have no choice but to put the front speakers far above ear level, aim them down as much as possible. If your speakers are asymmetrical (i.e., tweeter on top and woofer below), try turning them upside down. The dispersion pattern from asymmetrical speakers is also asymmetrical, so turning them upside down when they're mounted up high may aim the sweet spot toward the listening position. If the sound improves, great; there's no rule that says the tweeter must be on top. You may need to spin the manufacturer's badge around if you want it to read correctly, though. It's important to note that this won't work with vertically symmetrical speakers (i.e., tweeter in the middle with a woofer or midrange above and below), which have a symmetrical dispersion pattern that is the same whichever end is up, although it's much more narrow vertically than horizontally (this applies to all THX Ultra front speakers). For this reason, don't turn them on their sides. Do, however, aim symmetrical speakers at the listening position as much as possible.

Subwoofers in bookcases can be quite problematic. The biggest problems are the inability to adjust placement once installed and the annoyance of rattling objects. If at all possible, experiment with subwoofer placement before building the cabinet. Find the place along the wall where the subwoofer sounds best for the listening position, then put the subwoofer in the cabinet as close to that place as possible. If you must enclose your subwoofer in a cabinet, do your best to "float" it and minimize transfer of vibrations to the rest of the cabinet. Knickknacks buzzing, drawers chattering, and shelves clattering are immensely distracting. I recommend letting the subwoofer rest on the floor and building an escutcheon around it to make it look like it's in the cabinet, even though it really isn't. If this isn't feasible, cut a hole in the bottom shelf so the subwoofer can slip through and rest on the floor. Depending on the design of the subwoofer, a small stand may be required to lift it back up to the height of the shelf. The point is to avoid having the subwoofer touch the cabinet itself. If the subwoofer must rest on the shelf, vibration-dampening pads may help. Also, be sure to use subwoofers that only fire in a single direction and point that end of the subwoofer into the room. If your subwoofer has drive units on multiple sides, a port that's not on the same side as the drive unit, or a passive radiator that's not on the same side as the drive unit, it shouldn't be mounted in a cabinet. If it's amplified, be careful to ensure proper airflow for cooling.

So how do you determine optimum placement for a freestanding subwoofer? Unfortunately, there's no simple answer. I recommend starting with the subwoofer in one of the front corners of the room. In this location, the maximum amount of bass is produced, but it may not be especially even at the listening position. Carefully adjust the level of the subwoofer relative to the main speakers, from the perspective of the listening position, before proceeding. Even a small change in subwoofer level can create a large change in the perceived balance and quality of the sound. If, after adjusting the level, the sound is boomy at the listening position, try moving the subwoofer out of the corner. Adjust the level again and check for changes at the listening position. If good results aren't forthcoming, turn the tables on your subwoofer and place it in the listening position. That's right, give your subwoofer the best seat in the house! As it plays, walk around the perimeter of your room and listen for the spot with the smoothest bass response. I recommend choosing a location in front or to the side of the listening position. When you find a good-sounding location, move your subwoofer there. Be certain to carefully adjust the subwoofer level from the listening position once again. Keep experimenting, if necessary. If your system has multiple subwoofers, start with both of the woofers close together, but use this same procedure. If you can't find a satisfactory single location, then try moving the subs to separate locations.

Speaker placement is a complex mix of physics, acoustics, interior design, and common sense. Taking the time to think through the possibilities before installing your system is well worth the effort. I've given you suggestions here, but the complexities of the real world dictate that experimentation is necessary. Once you've decided where the most logical starting point is, try various placements and listen, listen, listen. I refer to this process as "dancing with your loudspeakers." Move your speakers, sit down in the main listening seat, and listen to familiar material for a minute or two. Try a new speaker location, sit down, and listen to the same material again. Lather, rinse, and repeat until you're satisfied that you've found the best-sounding location. In the final analysis, your enjoyment, both sonically and aesthetically, is all that counts.

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