A home theater system has between 5.1 and 7.1 channels. The point one, of course, is always the subwoofer. Would you be surprised to learn that buying one is not always the right decision? Certainly that advice would fly in the face of conventional home theater wisdom. One of the cool things about upgrading from the old stereo pair to surround is the reinforcement of bass frequencies that a good sub brings. In addition to underscoring dramatic moments in action movies, it also fills out the bottom string of a bass guitar and gives drumkits a solid presence that’s difficult and expensive (though not impossible) to achieve with just two speakers. As a bonus, routing bass to the sub allows the use of smaller satellite speakers in all the other channels, so a well-thought-out surround system may actually intrude less into an attractive room than a bulky, old-fashioned pair of full-range speakers. So why on earth would I advise you not to buy a subwoofer? One scenario is that your bleeding-edge home theater system has enough juice to run five to seven terrifyingly full-range speakers. You’ve got the muscle amp(s), the dedicated power line, and the sheer will to bass power. You are, in short, a special breed, and this column really is not about you. With all respect. As for the rest of you, if you’ve already bought a bad subwoofer, you knew from the start where I’ve been heading. I just don’t want you to waste your money on a one-note fart box that even a non-audiophile would find embarrassingly deficient: “Honey, would you turn it down? The children are frightened. Fluffy’s ears are bleeding. I want a divorce.” Save it, instead, for what you really want—a good subwoofer, one that’ll work well in your room, whether it’s a multi-purpose livingroom or dedicated home theater.
When Good People Buy Bad Subs Why do people buy bad subwoofers? Once it was because good ones cost too much. It seemed a bad sub was better than none. But nowadays, a really good subwoofer won’t empty your checking account. Outlaw Audio sells its LFM-2 for just $299. The same price will buy you the STF-1 from HSU Research. (In addition to marketing his own products, Dr. Hsu is a design consultant to Outlaw.) If people buy bad subs to save money, they’re not doing it because good ones are unaffordable. They’re simply not well informed. Another reason to buy a bad sub is that it comes with good speakers. Speaker packages are both a boon and a bane to the home theater buff. Not every good set of satellites comes with an equally worthy sub. If you can’t buy one without the other, better look elsewhere. Find a package of sats that come with a good sub—or find a manufacturer who will let you buy each speaker singly or in pairs, with the sub as a separate purchase. Then you can mate your speaker picks with the cool sub from HSU or Outlaw (or Velodyne or Pinnacle or…). Perhaps the most disappointing sub is one with multiple personality disorder. In a room of ideal proportions, it can propagate bass like a master. But put it in a room of the wrong proportions and acoustic conditions turn it into a devil, generating standing waves between parallel walls, and turning the room into a giant bass resonator that exaggerates one incredibly obnoxious frequency. Is your room a cubbyhole of acoustic contagion? This handy standing wave calculator may help you find out. As a general rule, the worst rooms are cubes, or have two or more matching dimensions, or have a dimension that’s a multiple of other dimensions. A bad room can turn a good sub, even a great sub, into a bad one. In that situation there are two solutions. One is to call in an acoustics expert—who might be a custom installer—and have him fix the room with wall treatments and bass traps. This can be expensive, though an inspired and knowledgable DIY type might make progress this way. For the non-tinkerer, an easier solution is room correction via equalization, using a glorified tone control to notch out the offending bass peak. Pioneer and others build room EQ circuits, and auto-setup features to get them running, into surround receivers. In surround preamp-processors, TacT is the go-to company for those with high standards (and budgets). The bad news about room correction is that it may do more harm than good when also applied above bass frequencies—as room-correcting receivers typically do. The good news is that for bass-related problems, it works extremely well. Even better news is that room EQ is built directly into subwoofers by Infinity, Mordaunt-Short, Revel, and Sunfire. That allows you to treat your room’s bass problems and leave the rest alone. Some subs have trim controls that adjust only fixed frequencies. They are less precise than user-set variable EQ, but might do the trick in some situations. A smart sub costs more but it’s worth it. One of the more affordable specimens is Infinity’s SW-12 ($899). Controls on the sub adjust the frequency, volume, and width of the notch. For best results get an optional kit that comes with a test-tone CD and a meter optimized for measuring bass. Measuring is crucial—rooms differ, and you need to quantify the problem before implementing the solution. I’ve reviewed Infinity’s equalized subs a couple of times and they always make my room sound better. Yes, sometimes even a critic has standing-wave problems in his own listening room. Problems, Solutions Let’s move forward to problems and solutions. Problem: You’ve got a good sat/sub set with a bad sub. Solution: Admit your error and buy a better sub for $299 and up.
Problem: You’ve got a good sub and a bad room. Solution: Get an equalized sub for $899 and up.
Problem: You’ve got your eye on a sat/sub set but, having been a smart cookie and done some listening, you find the sub is not up to snuff. Solution: Don’t buy that package. Or take advantage of the money-back guarantee while there’s still time. Finally, an especially knotty problem: You’ve fallen in love with a good set of speakers, but it’s pricey, and you’re tempted to compromise on the sub. Solution: Don’t buy that sub! Every dollar you waste on the wrong sub is a dollar you could have put toward the purchase of the one you’d really cherish. If you spend a couple of hundred bucks on a piece of junk, you’re a couple of hundred bucks further away from your goal. How postponing the sub purchase will affect the rest of your system depends on how much bass response your other speakers have. The key thing here is the crossover between satellites and subwoofer. If your new speakers require a crossover of 100 Hertz or more—something you may be able to find in an online instruction manual before you buy—they won’t even reproduce the lower part of a male voice without a sub. Here are a few scenarios for coping: (1) If at least two of your new speakers are full-range, with considerable low-bass response, you can set the front left and right channels as “large” in the receiver’s setup menu, and the center and surrounds as “small.” The system will route bass frequencies to the two “large” speakers. This won’t be as effective as having a good subwoofer, but it will tide you over till you can buy the right sub. (2) Remember those old full-range speakers I ridiculed in the second paragraph? They may still have some uses after all. Use them as the front left and right speakers, as above, along with your new center and rear-surrounds. This is not a good longterm solution because your old speakers probably won’t match the center and surrounds, especially in the tweeters, leading to an uneven soundfield. But it might be better to live with an uneven soundfield temporarily than to live with the wrong subwoofer forever. (3) If you’re looking at bookshelf or monitor-size speakers, with good bass response down to at least 80Hz, and a gradual gentle roll-off below that point, they may have just enough mid and upper bass response to satisfy you—for a little while. Designate them all as “large” in the receiver’s setup menu. Your system would underplay the open bottom string of a bass guitar, at 42Hz, but at least voices would sound normal. Examples that I’ve reviewed over the years include the Era Design 4, Paradigm Titan, and PSB Alpha B. To find out about bass response, read test reports in Home Theater, UltimateAV, Stereophile, and other publications. (4) If your new system uses small satellites with a 100+ Hertz crossover, and you have no full-range speakers to fall back on, don’t pull the trigger till you’ve got enough to buy the whole speaker system, whether it’s a single package or a combo you’ve pieced together yourself. Whatever you do, don’t spend your money on a subwoofer unless it’s the one you really need and deserve. Mark Fleischmann is the author of Practical Home Theater, audio editor of Home Theater Magazine, and tastemaster of happypig100.com.
The views expressed here are solely those of the author and do not reflect the beliefs of Digital Trends.