Legacy Audio Whisper loudspeaker By Paul Bolin   •   August, 2006 More than any other component, it is the loudspeaker that seems to invite the most audacious—some would say flat-out lunatic—efforts at design. There have been attempts at full-range plasma speakers, speakers one had to hook up to tanks of pressurized gas, speakers with drivers attached to what looked like copper salad bowls (the infamous Tri-Torr of the early 1990s).

One look at the Legacy Audio Whisper with its grille off and it's easy to see that Legacy's Bill Dudleston is one of the more seriously experimental designers of loudspeakers. Thankfully, his philosophy is based in well-grounded scientific research and the goal of truly high-fidelity sound, rather than the use of novel methods for their own sake or repackaging good old-fashioned snake oil.

When I visited the Legacy factory as a part of my review of the Focus 20/20 speaker, I had a chance to hear the Whispers. I'd seen them at shows, and the design—all those drivers!—seemed to go against the conventional wisdom of "simpler is better." What I heard in Legacy's listening room shattered my preconceptions about complexity per se being an impediment to impressive sound. A few months after my review of the Focus speakers appeared in the January 2004 Stereophile (Vol.29 No.1), Legacy's Bob Howard called and asked if I'd like to experience the Whisper at home. I quickly agreed, and a few weeks later two massive crates tall enough for me to stand in without ducking (I'm 6' 1") and a small box containing the Step One bass processor arrived. Legacy's local dealer helped me uncrate the very substantial speakers and wrestle them into my listening room. Once down the stairs, the Whispers were easy to move around; they're on casters.

A legacy of innovation
Bill Dudleston had five design criteria for the Whisper: 1) Minimize the room "noise" (early reflections) that normally masks ambient information and spatial cues, while maximizing channel separation; 2) Minimize the excitation of low-frequency room resonances, which blur transient detail and color the sound; 3) Provide the proper ratio of radiating surface to frequency, to control dispersion and minimize THD; 4) Provide broad dynamic range and high efficiency; and 5) Create a sweet spot large enough for multiple listeners. Everything that is different about the Whisper is geared toward the realization of those ends, and Dudleston's goal of "creat[ing] the most undistorted mirror of the microphone to date." Before sitting down at the computer to design the Whisper, he gathered data from 75 different listening rooms over a four-year period in order to arrive at the optimum dispersion pattern that would minimize room interaction and maximize the sweet spot.

Stripped of its front and rear grilles, the Whisper can be seen to comprise, like Caesar's Gaul, three distinct parts: top and bottom pairs of woofers, and the center section, which houses the mid-woofers and tweeters. The main portion of the speaker consists of two baffles, mounted 2¼" apart. The rear baffle holds the second set of open-air woofers, which are mounted back-to-front; the front baffle holds the front woofers, four mid-woofers, and two tweeters.

As noted, the Whisper doesn't look like most other top-echelon speakers. When the Whisper's grilles are off, the visual effect of all of Dudleston's computer-modeled dispersion control is somewhat that of a Mighty Wurlitzer, though I found it cool and retro. If there's such a thing as Edwardian high-tech, that's the Whisper's style. Conscientious objectors can leave the grilles on with no great sonic penalty.

To minimize room interactions, the Whisper's design was focused on projecting a highly controlled and predictable radiation pattern—the speaker is designed to have no more than 90° of horizontal dispersion at any frequency within its passband. Legacy describes the speaker as an "acoustic gun." This goal is no easy thing to accomplish with low frequencies. A large woofer in a box—any woofer in a box—will behave as an omnidirectional radiator. Dudleston therefore eliminated the woofer box entirely. The two pairs of closely-spaced back-to-front, in-phase 15" woofers behave like the twin diaphragms of some directional microphones; the result is a tight figure-8 directivity pattern with a null at the speaker's sides. (That there's a truly massive null at the speaker's sides can be confirmed easily by ear.) The Step One bass processor, installed between preamp and power amp(s), serves to adjust the Q and level of the woofers to let them couple effectively with the room without compromising their controlled dispersion. The Whisper also has a 12" passive radiator on the back of the central section, said to absorb excess bass energy bounced off the wall behind the speakers.

The four midrange units, according to Dudleston, "appear" to the ear as a single 14" oval driver, which will be more directional than each on its own. Each is mounted in its own subchamber, which is stuffed with polyester fiberfill to absorb backwave energy. The dome tweeter and ribbon supertweeter are placed at the center of the oval in a waveguide of variable-density foam. The ribbon tweeter is rotated 90° to provide controlled horizontal and wide vertical dispersion.

The Whisper can be biwired or biamped via its two pairs of gold-plated binding posts, and all internal wiring is Legacy's own OFC copper. Fit'n'finish were excellent, and the lovely ribbon-mahogany premium finish had the kind of tiger-stripe effect one sees on the maple tops of fine old Gibson Les Paul Standards. I would like to see the binding posts mounted to an external metal plate, however; one post moved a bit when I cinched down my speaker cables.

The Whisper's relative lack of room interactivity (about which much more later) allows for a great deal of flexibility in setup and positioning. They can be pushed much farther back into corners than more conventional designs, and their bass output can be tailored with the Step One. However, like most speakers, especially large ones, the Whisper will perform best when given some room to breathe. In my room, the speakers initially settled at a spot 54" out from the front wall, quite close to the sidewalls, and toed in at a very acute angle, the tweeter axes crossing well in front of me. The extreme toe-in is recommended by Legacy to maximize the effects of the speaker's tightly controlled dispersion pattern and to minimize the effects of the room. The result was a sweet spot surprisingly large in lateral dimension with no sacrifice of center fill.

A legacy of power and subtlety
Despite its size and considerable weight, the Whisper's sound was not at first a typical "statement"-speaker sound, principally because of its bass. As the drivers are mounted in an open-air configuration, there are no box colorations to overcome. The amount of bass is left to the tender mercies of the owner, and the Step One must be adjusted with care. It was easy to make the sound too lean, and even easier to crank the processor up too far, for a sodden, muddy sound. It was easy to get the Whisper to sound good, but I found that patience and an attentive and musically attuned ear were necessary to attain the speaker's considerable best.