Bass in Your Space: Woofin’ on Subwoofers

Too much of a good thing can spoil or at least dampen the pleasure derived from just about any experience. Like the way a tony restaurant’s cloyingly ultrasweet desserts can make your teeth ache. Or the way buying the fifth remastering of Kind of Blue in a decade makes you wonder if technology isn’t becoming more important than the music. Or the way too much bass from a subwoofer can spoil one’s enjoyment of the home theater adventure.

No doubt about it. A subwoofer can indeed be a good thing, but improperly matched or incorrectly dialed-in with your main speakers, or located in the wrong place, the thing can throb and boom to a most unpleasant and most unnatural degree. The result can be distracting, unmusical and can mar the overall sound of an otherwise great system.

Subs are possibly the least understood component of a home-theater setup and can certainly be the easiest link in the chain to set up poorly because it takes a great bit of trial-and-error adjusting to get the thing right, and most folks are not willing to take the time and effort it takes to go through all the steps as they should. In addition, there are a lot of mediocre subs being marketed today, many of which cannot even get close to the low frequencies a legitimate subwoofer can reach, or are so wrought with distortion that the quality of the bass that is present only serves to degrade the resulting overall sound.

The role of a good sub is to handle all the true low-bass material of music and movies from 100Hz or so down to 35Hz or even lower-they must be capable of moving large amounts of air with a minimum of distortion. To ensure adequate juice to the woofer, most subs today are powered subs, meaning they have their own self-contained amplifier used exclusively for this specialized speaker’s handling of low frequency material. Your main system’s performance benefits from adding a sub since, in addition to adding extra bottom to the sound, your primary amplifier and speakers will no longer be called upon to produce anything under that approximate 100Hz cutoff point. Since this is the most difficult range of the audio spectrum to reproduce, your main system will not have to labor as hard-in a sense allowing it more muscle for reproducing the mid-bass, midrange and highs. With the powered sub doing all the hard work, the rest of the system usually sounds smoother and more musical.

There are two kinds of extremely stressful bass information which subs are often called on to reproduce in addition to the normal tones of a walking acoustic bass: sharp, sudden bursts of energy like an orchestral bass drum or a car crash, or prolonged bass energy such as long-held pipe-organ tones or those suspense-building low rumbles often found on movie soundtracks that can go on for a minute or two as the plot thickens, like just before the Terminator begins a particularly hairy battle scene. Both of these can create a severe strain on any sub, and some designs have special circuits in their amplifiers to help prevent the sub from simply cutting off during these periods of stress, as many inferior subs do. This is something to listen for in auditioning any model-can the unit perform without cutting out during particularly demanding passages? PSB tests its new designs by ratcheting the sub up to its max and letting it coast for 15 hours. If it is still functioning, the design goes into production.

So what does it take to set up a subwoofer properly? Again, lots of trial and error.

Of primary importance is the placement of the box itself. Because of the nature of sound waves, the intersection of the wall with the floor is one place that reinforces those low waves and the place where two walls intersect with the floor-aka the corner of the room-will offer the maximum in wave reinforcement, meaning that if you put the sub in the corner, you’re likely to get the most bass. But that is not necessarily the best place in your room to achieve the best sound; when the bass is reinforced too much it can be muddy and boomy. One way to find out what works best is to simply move the box from location to location-even a few inches can make a difference-and see what sounds best while playing a disc featuring some heavy bass material. But that box can be heavy. Some recommend the following technique, which sounds utterly weird, but makes perfect sense. Begin by placing the sub in the listening position, i.e., the chair or sofa where you’ll sit when bathing in your home theater, and try to get the sub high enough in that spot that it is more or less positioned where your ears will be. Then, and I am not making this up, crawl around on the floor-with your ears roughly at the height of the actual speaker port on the box-until you hear the best, cleanest bass response. That place is where you want to locate your sub. Once you locate the “sweet spot” for the box, you can proceed to fine tune the various settings until you achieve the optimum setup.

First adjust the crossover point with the control on the back of the sub. The crossover point is the location on the frequency spectrum where the sub picks up and the main amp and speakers leave off-what you are doing with this setting is establishing the upper limit of the sub’s frequency range. A good starting point is around 80Hz, depending on how large your main speakers are. Secondly is the phase control, which helps prevent the upper frequencies of the sub from canceling out the lower frequencies of the main speakers and must be adjusted by listening. Tweak this until you get the smoothest sounding result.

Then there is the volume level of the sub. Don’t crank this up as much as you think you need it. Be judicious or you’ll get to that “too much of a good thing” setting. Again, it can be done, albeit only approximately, by ear. But the pros do it with an inexpensive sound pressure level (SPL) meter from Radio Shack or other electronic supply store. With such a device you can calibrate your speakers-front, center channel, surrounds and sub-to the correct levels so that your system is truly in balance. This is done by using the test tones of your A/V receiver (or by playing a special calibration disc) and using the SPL meter to calibrate each speaker one-by-one to the same volume level. It sounds complicated but it isn’t, and it’s the only way to guarantee proper balancing of six different speakers.

After following these guidelines and the more specific instructions included with your sub (and those of your A/V receiver), the aural envelope created by your system should carry you to far off places, planting you right in the middle of all the action portrayed on your video screen. Home theater can be nothing short of breathtaking when all the parts are working as they should, in large part due to the foundation provided by a good, well-adjusted sub that unveils the magic of those low frequency special effects and the deepest depths of a double bass.

Here are a few subwoofers worth investigating:

In the world of high-quality loudspeakers, PSB possibly leads the pack in terms of value; its products consistently offer performance beyond their modest pricing, so we’ll look at a handful of subs from PSB’s lineup. For small rooms and apartments you may not need anything beyond the PSB Alpha SubZero i ($329). It features an 8-inch woofer and a 100-watt amplifier capable of delivering 260 watts of dynamic peak power and offers usable bass down to 32Hz. Its modest 9x13x14-inch cabinet makes it perfect for any environment where space is an issue, and though not earth-shaking its bass is quite respectable for such a small enclosure. For larger rooms and more ambitious systems, investigate the PSB Image SubSonic 6i ($699). This baby features bass extending down to 26Hz from a 12-inch woofer and a 225-watt amplifier capable of 600-watt peaks. If you want to go a step further up the ladder, consider the PSB Stratus SubSonic 7 ($949), which is capable of moving tons of air via its 15-inch woofer driven by a 330-watt amplifier. Bass extends down to 20 Hz, which is deep enough for just about any musical instrument-or any helicopter crash-you can throw at it.

Paradigm is another Canadian loudspeaker company that, like PSB, packs more bang for the buck than most manufacturers, and this is no less true for their subwoofer offerings. The Paradigm PDR-10 ($349) is a good place to start and can make windows rattle, belying its relatively small size. It features a 10-inch woofer and a 100-watt amp capable of 300-watt peaks. At the top of the Paradigm line is the Reference Series, and within that lofty grouping lies the Servo-15 sub ($1,500), which features a 15-inch woofer and a muscular 400-watt amp capable of 1200-watt peaks. This thing weighs in at 90 pounds and plumbs down to an amazingly low 14Hz, so make sure you are on good terms with your neighbors before cranking this one up too high!

Dynaudio, the Danish company long known for the high quality drivers it supplies to other speaker manufacturers, has spent the last 10 years or so introducing its astonishingly detailed and convincing loudspeaker designs to the U.S. market. Its entry-level sub is the Audience Sub-20A ($1,088) and it’s a doozy. Sporting a 10-inch woofer and a 90-watt amplifier, it pumps out very tight, real bass down to 25Hz. Dynaudio has staked its reputation on building highly accurate speakers and this one is no exception. The bass is well-defined and punchy, the way it should be.

Hsu Research is a small company that has created large waves (literally and figuratively) in the world of high-end audio by selling subwoofers, and only subwoofers, direct from their California factory. MIT-schooled Dr. Poh Ser Hsu focused his research on subwoofer technology and has created a line of subs renowned for their performance and relatively low direct-to-the-consumer prices. The VTF-3 ($849; $1,035 in rosewood) combines a 12-inch woofer (with a massive 120-ounce magnet structure) and a 250-watt amp to produce bass down to 18Hz. No, you can’t audition this at a dealer’s showroom, but Hsu offers a 30-day money back guarantee, so if you don’t like it, you can return it. This essentially translates as an in-home audition, and that is always the best way to try out new equipment.

Richard Vandersteen of Vandersteen Audio, an admitted tinkerer and perfectionist, has a reputation for creating products that excel at getting the job done in a no-frills kinda way, sinking money into sound instead of bells and whistles like pretty cabinetry-his resulting loudspeakers are the best evidence of his philosophy of function over form. While his boxes will win no awards for their beauty, they are consistently lauded by critics around the world for the lifelike sound they produce. Vandersteen’s approach to sub design is no exception to his rule. The exterior of the 2Wq ($1,295) is plain, but the inside is full of surprises. Instead of one large woofer, he instead employs three 8-inch woofers because smaller speaker cones can move more nimbly, more rapidly than larger, more massive cones, thus improving pitch definition and accuracy. His three smaller cones move the same amount of air as a 14-incher, but are much more musical because of their faster speed. The internal amplifier delivers an extremely muscular 300 watts, plenty of juice for just about any low frequency task it may encounter. And like all Vandersteen speakers, this unit is designed to accommodate future improvements as they become available, so the Vandersteen you buy today will never become obsolete if you choose to follow the upgrade path.

If a sub is in your future, shop with your ears. And if you already own a sub, spend the time it takes to set it up correctly. The rewards in improved sound from movies and music will be well worth the effort.