3D Connexion IL120s specifications Specifications, Equalization

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E Q U I P M E N T R E P O R T

SUBWOOFER

Infinity Systems Interlude IL120s

As everyone—at least, every- one who reads this magazine—knows, the sound of a subwoofer in a room depends not only on the subwoofer itself, but also on the room and the placement of the sub- woofer in the room. You can have a sub- woofer that’s a sterling performer when measured anechoically, but that perfor- mance may not be realized in a given home- theater setting. While some of us are in the fortunate position of being able to build a dedicated home-theater room of ideal pro- portions, most of us are stuck with the rooms we’ve got, which leaves subwoofer position as a variable to be optimized.

There are formulas and computer pro- grams that will suggest subwoofer position- ing, but, in my opinion, these are not as use-

ful as they seem. The ones I’m familiar with all use a mathematical model that assumes a shoebox-shaped room with no openings in the walls, and walls of infinite rigidity. Real rooms may be L-shaped and have doors, archways, closets, skylights, and cathedral ceilings—variables that can’t be plugged into the formulas. Real walls typi- cally have rigidity that is considerably less than infinite, which can affect the useful- ness of the result in ways that are often unpredictable.

One bit of advice that’s hard to argue with is that the subwoofer should be moved around until you find the position that pro- duces the best bass—i.e., the greatest exten- sion, the most output, the flattest frequency response, and the smoothest integration

Robert Deutsch

with the main speakers. Fair enough, but even if you ignore the possibility that you’ll have to make tradeoffs among the different criteria of subwoofer performance (for instance, the position that gives you the high- est output might not produce the smoothest integration), this approach assumes that you have considerable flexibility in subwoofer positioning. Again, the reality may be quite different. The position that’s ideal for the sub- woofer may be exactly where you have the equipment rack, with no other convenient place in the room to put the equipment. Or the subwoofer might sound best when placed in a position that will almost guaran- tee that people will trip over it or its cables.

Equalization

SPECIFICATIONS

Interlude IL120s ported active subwoofer	Weight: 45 lbs.
Driver: one 12" C.M.M.D. cone	Price: $899; Bass Optimization Test &
Frequency response: 28–150Hz, ±3dB	Measurement Kit, $59.95
Amplifier output: 500W (20–150Hz,
<0.1% THD)	Manufacturer
Crossover frequencies: 50–150Hz,	Infinity Systems
24dB/octave, continuously variable	250 Crossways Park Drive
Controls: subwoofer level, phase (0°/180°),	Woodbury, NY 11797
crossover frequency, R.A.B.O.S. (see text)	tel. (800) 553-3332
Finishes: cherry, natural maple, onyx-onigre	fax (516) 682-3524
Dimensions: 171⁄2" ⋅ 171⁄4" ⋅ 193⁄4"	www.infinitysystems.com
(H⋅W⋅D)

One approach to improving in-room sub- woofer performance is equalization: atten- uating the peaks and boosting the valleys, a process intended to produce an overall more linear frequency response. Unfortu- nately, there are several pitfalls to using conventional equalization in this fashion.

First, boosting a frequency that corre- sponds to a dip in the frequency response is not advisable. A dip usually indicates acoustic cancellation, and boosting the level at this frequency is like feeding power into an acoustic black hole. You’ll end up pushing the subwoofer to high output lev- els, with little to show for it, except possibly driving the woofer into audible distortion.

Attenuating a peak might be effective,

74Stereophile Guide to Home Theater • November 2001