March 2000Wilson Audio Specialties XS Subwoofer
by Jeff Fritz
The Wilson Audio Specialties XS subwoofer is the most expensive, physically impractical passive subwoofer ever created. This says nothing about the products value, but is, in fact, a consideration for the potential customer. The XS retails for $18,200 in standard finish without a crossover or power amplifier (Wilson will supply a crossover for an additional $4000). This alone makes it a limited-production piece that is a rarity to hear outside of an electronics show such as the CES.
If you can get past the cost, an equally imposing roadblock awaits you (or a reviewer). The physical size of the XS is a big problem, not from an aesthetic perspective, but as a logistics equation. Let me explain. The XS is over eight feet tall and weighs over 700 pounds plus another hundred or so for the crate. The shipping company hired to deliver the XS to my home left a message on my answering machine that stated "you need to call our office as we need to discuss your receiving capabilities." At this point I began to realize that this was not just another component that I could unbox with a couple of buddies and then listen to. I had to plan.
The first question was where I could place the sub so that it would be out of the way (answer: nowhere) and sound good (you dont just play with its location). I had already moved the audio system out of my dedicated listening room and into the main living room of my house because of the impossibility of the former space to handle both the Wilson X-1s and the XS. Once a location was chosen from my available choices of one, I began planning for the XS's arrival. The sub would be placed along the side wall, but close to the back wall, of my new listening room. It would be approximately the same distance from the listening position as the X-1s, about 12 feet. Furniture was rearranged, and my very patient, loving wife helped assemble the new room for optimum equipment placement.
The day the XS arrived I was in a great mood as the sun was shining and a long weekend was ahead for tweaking the sub and listening to music. The shipping company assured me that they would have it in my house and in place without much ado. "We do this all the time," they said. Well, suffice it to say that after about two hours and a broken piano dolly later, the shipping-company folks left soundly defeated. The XS was not to be installed that weekend. After regrouping and developing a new plan that included professional piano movers, another attempt was made. It still took about two hours to go from my garage to the living room, but eventually it was in place. As I stared at the XS standing there, I curiously noted how small the X-1s seemed. "Kind of like minimonitors," I muttered. My wife cried. I could not help but curse David Wilson for creating such a product.
The next step
I had the foresight to connect the speaker cable to the sub before backing the sub into the corner. This cable was a 6' length of Harmonic Technology Pro-9, to match the main cables Im currently using. The connection of the subwoofer into the main system was fairly straightforward. For the review, a Wilson GSB electronic crossover was supplied. This unit is fed the main stereo signal from your preamplifier and outputs a high-pass stereo signal to your main amplifier and a mono low-pass signal to the subwoofer amplifier. The amps I used to power the XS included a Krell KAV-250a and the powerful Parasound 2200 Mk II, both in bridged mode. One channel of a Threshold S550e was also auditioned. I battled a ground-loop hum throughout the review period, which accounts partially for the various amplifiers I tried.
The rest of my system included the Wilson X-1 Grand SLAMM Series II speakers, a Coda 04r line-stage preamp, the Pioneer 606D DVD player, and various power amplifiers including the Simaudio W-5. Cabling was primarily Harmonic Technology and Transparent Audio, in several configurations. My room is somewhat strange in shape but is actually working out quite well. The listening position faces a parallel wall, which houses a fireplace. This wall is built into a corner so that the speakers fire diagonally across the room. This has proven to be helpful in minimizing side-wall reflections. Furnishings and rugs treat a fairly live room successfully. I am missing my dedicated AC lines that I had in my upstairs room, but this is curable.
There really isnt a lot to tell you about the XS as it is fairly simple in design, although not simply implemented. The cabinet is a combination of proprietary "X" material and MDF. It is heavily cross-braced with two large aluminum ports, each serving one driver. The drivers themselves are 18" units that reportedly are the finest available. Power handling is rated at 1600 watts and compression is minimal even at extreme sound-pressure levels. The grille is located on a front decoupled baffle board. Two large custom binding posts are located on the rear, near the bottom of the cabinet. One feature that is representative of the quality that goes into the XS is the large brushed-aluminum ring that covers the mounting hardware of each driver. These are huge, with the companys name engraved near the lower edge. This creates a sandwich for the driver to rest in. Unfortunately, there are no casters or feet available for the XS. Im not sure if this has to do with the weight of the unit, but it sure would be nice to have some way to place the sub on a floor so that the thing can be moved. The review sample was placed on a foam pad and in turn the pad on a blanket. This did allow the unit to slide on my wood floor, but there has to be a better way. Rated frequency response is -1.5dB at 15Hz, but during testing Wilson Audio measured strong response below 12Hz. Nominal impedance is 4 ohms, while sensitivity is 95dB.
A good subwoofer should be felt, not heard. This implies that if you can determine the location of the subwoofer, it is crossed over too high as some midrange information is leaking through. This was not a concern with the XS because the crossover point was factory set to match the X-1 Grand SLAMMs at a low 35Hz. I tried the XS in two configurations. The first was Wilsons preferred method of crossing over the X-1s so that they hand off below the crossover point to the XS. The second was running the X-1s full range while bringing the XS up in level "underneath" the mains. Both methods yielded good results. If your goal is to relieve the mains from the extreme low bass to increase power handling and absolute sound-pressure levels, using the high-pass crossover is a good idea. My guess would be that WATT/Puppy owners would benefit here. The X-1s, on the other hand, are capable of stunning low-frequency response due in part to the excellent Focal woofer combination. To lose this performance seemed a waste; therefore I tried combining the X-1s with the XS, which actually smoothed the response. Power handling is not a concern with the X-1s, so that did not enter into the equation.
The impact that the XS had on the sound of my system was phenomenal. Once the whiz-bang effects were out of the way, like shaking Wedgwood off shelves three rooms away, I listened seriously to as many music selections as I could find with low bass. Ive come to realize that there is more low bass present in many recordings than I had previously thought -- not only music, but also the resonant character of the acoustic space. This must be extremely low in frequency as much of it escapes even the X-1s. As an example, listen to James Horner conducting the London Symphony Orchestra on the Braveheart soundtrack [Decca 448 295-2]. On the track "Attack on Murron," at about two minutes in, the bass is thunderous. In addition, the soundspace envelops and melts the walls, leaving you with a close approximation of the recorded event. The soundstage expands, exposing the ambient cues hidden in the recording for the first time. More than once I left my seat to look outside, go to the front door, or upstairs to investigate sounds I would have sworn were not coming from the stereo. It was quite spooky.
The listening level chosen for each recording was directly related to the work being reproduced. A jazz club was realistically approximated at a medium volume while Metallicas "Nothing Else Matters," from their Black [Elektra 9 61113-2] album, was played at levels that mimicked the live event (which Ive heard a number of times). On this recording, the sheer impact of the sound must be experienced to be believed. When the kickdrum enters, a physical blow is delivered that is as angry as Hetfields voice. Its quite exhilarating.
Harry Connick, Jr.s "Joe Slam and The Spaceship," from his She CD [Columbia CK 64376], envelops in a way that makes you feel you are part of the recording. The scale and majesty of the bass is simply bigger and more powerful than Ive ever heard before from reproduced music. Although the XS produced massive amounts of bass, it also completely disappeared into the system. This was the case not only at the listening position, but around the room at other points as well. I realized that the existence of the XS was simply for the reproduction of super-low-frequency information at realistic sound-pressure levels. You may be saying "duh, Jeff," but you forget that many listeners purchase subwoofers to reinforce upper bass and midbass that their main speakers are not producing. This invariably leads to disappointment because poor blending typically occurs. One reason for the seamless integration of the XS into my system was the prodigious low-end capabilities of the X-1s. I realized that this allowed the two systems to "meet" on their own terms without a gap to highlight the existence of the other.
X-1 versus XS
Massive Attacks Mezzanine CD [Virgin Records America 7243 8 45599 2 2] contains sustained bass that will test even the mightiest of systems when played at high levels. Using this recording, I was able to test the two systems in absolute terms. Lets make this short and to the point: Even though the X-1 is one of the most capable speakers of all time in low-bass performance, the XS devours it. The X-1 is visceral, fast, punchy, and will fill even large rooms with 20Hz bass. The XS is limitless, bottomless, and gives "effortless" new meaning. The difference is in scale and magnitude. The X-1 can shake the room; the XS can rip down the walls and be felt at the end of my street. They are equal in terms of speed and transparency. I never had the impression that the XS lagged behind the music, which was somewhat surprising. Its grip and tautness gave no indication of the massive cones delivering the sound.
Its impossible to say whether the success I had integrating the XS into my system will work for speakers other than the X-1s, or Wilson speakers in general. Surely some of the synergy I experienced comes from the fact that the XS was designed as a natural partner for the X-1 and WATT/Puppy. I would say that speakers that already possess excellent low-frequency response probably would have the best chance of integrating with a super-subwoofer like the XS.
The XS delivers bass that transcends anything Ive heard, in both quality and quantity. It is so impractical from size and price standpoints, its really a wonder it even exists. The XS is about smashing boundaries that existed before its creation. The low bass capabilities of my X-1s certainly satisfy, but in the search for the absolute, it occurred to me that the XS was created for a reason, which is answered loudly and clearly upon listening to the XS paired with the X-1s. Although its performance is hard to fathom, the XS does unquestionably live up to its name, which I guess says it all.
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