Wilson Audio Specialties X-1/Grand SLAMM loudspeaker system Page 4

The X-1 revealed such great differences between speaker cables that it was hard to be dogmatic about which product was responsible for certain sounds we heard: the X-1, or the cables themselves. At an early stage of the initial installation, the Krell KRC-2 preamp was temporarily laid on the carpet. So analytical were these speakers that the placement of coupling cones under the preamp was immediately recognized in the tighter bass and cleaner mid! The same trick was repeated, this time with the Krell KSA-200S power amp. Such transparency on the part of the X-1 promised much entertainment later.

With such a high potential performance, the X-1/Grand SLAMM was correspondingly highly critical of location. The design aims at neutrality; to achieve this, it was essential that an optimum placement be defined for each of the speakers as well as for the listener.

Each room presents its own problems. In my case, the obvious arrangement didn't work very well (see the room-response graphs in the "Measurements" sidebar), resulting in a rather brash sound which severely lacked bass weight. Considerable experimentation with placement was needed to find primary positions that would result in a subjectively evenly balanced bass, combined with optimum low-frequency extension. Once these positions were found, the fine-tuning could begin.

Before doing anything else, Dave Wilson demonstrated his room-calibration procedure. Reading continuously from plain text, he slowly paced across the breadth of the room and along several axes down its length, all the time listening for the effect of the damaging room acoustic and local boundary reflections. He then mapped zones in which the "return" sound of his voice was most neutral, these lying in the general area proposed for the speakers, the zones defined for the sides of the room. This work resulted in parallel "tracks" marked on the carpet along which the speakers could be moved when adjusting their distance from the rear wall to give the best low-frequency match. I then placed myself alternately at the two speaker positions; while I read out loud, Dave identified the optimum distance for the listening seat, again looking for the cleanest and clearest speech quality.

Once the general positions had been identified with some precision, we were able to start the micro-tuning. Any speaker will generate a complex comb response due to local boundary reflections. Wilson takes the view that the reflection structure has a "grain"; you can go with it or against it. The comb-response detail is not evenly spread; rather, it occurs in bunches that can be quite compact in the midrange—just a few inches wide. By fine-tuning the spacing of the speakers from each side wall and analyzing it subjectively in increments of as little as half an inch (using calibrated masking-tape markers on the floor), it was possible to further improve the matching of the sound character, and the micro-response and balance between the two channels.

A fine adjustment is required for the upper-midrange to low-treble balance; Wilson uses a chosen track from his first Ragtime Razzmatazz recording to explore the purity of the complex harmonic tone of the piano notes, seeking the optimum boundary placement.

In my room, the X-1 was placed closer to the back wall than we had originally expected; but the size and proportion of the large rectangular bay window behind the speakers was an unexpected acoustic bonus—the X-1 could breathe sufficiently for fine soundstage space and depth to be generated.

Though Dave Wilson used to personally install the WAMM system in customers' homes, factory personnel have been trained for the job of installing the X-1s. This service is a Wilson Audio Specialties preferred option. Given the complexity of the system, the high-gloss finish, and its considerable weight, the presence of a Wilson Audio installer must be considered a valuable service.

For this project I enjoyed the support of many colleagues who contributed comments on the sound of the X-1 in my room. These included John Atkinson, Paul Messenger, Paul Crook, Chris Bryant, Jonathan Honeyball, and Steve Harris.

Listening Sessions, Room 1
The die is cast. Just as Dick Olsher's view of audio was irrevocably changed by the experience of a fine single-ended, class-A triode amplifier driving appropriate speakers, so have my views been altered by the X-1/Grand SLAMM experience. Until I heard the X-1, I simply didn't know that it was possible to hear certain qualities in recorded music. The X-1 appeared to achieve the impossible on many occasions.

More often than not, the assessment sessions turned into periods of pure listening pleasure. Each new disc—analog or digital—was a revelation. The X-1s became a vehicle for the renewed exploration of my music library. My favorite discs were discovered to be both familiar and unfamiliar—familiar in tonal character, reflecting the speaker's high accuracy, but unfamiliar in terms of the wealth of hidden detail that was suddenly revealed, this ranging from the superior level of clarity and dynamic expression to the attack, speed, and note-playing discrimination that appeared in the bass. And all this was before I played the speakers loud!

A great advance in sound quality such as this is a rare event; unquestionably, the X-1 is a major achievement in loudspeaker design. The Wilsons generated an unmistakable sense of presence, with a grip on the musical event and a vivid re-creation of performance. Somehow they took hold of the air in my room and the sound of the enclosed space and spoke directly to me.

Wilson Audio Specialties
2233 Mountain Vista Lane
Provo, UT 84606
(801) 377-2233
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