Floor Loudspeaker Reviews

The latter is important in light of the high-frequency driver chosen for the Essence: a 2.5" aluminum-alloy ribbon manufactured by Tang Band of Taiwan. The TB tweeter has a powerful neodymium magnet—metal tools must be used with caution, if at all, in the vicinity of the Essence's baffle—and a matching transformer brings the ribbon's impedance in line with that of the 10.3" main driver. The tweeter is driven through a second-order high-pass filter, and is blended into the main driver's output beginning at about 10kHz; the output of the full-range driver, which is wired directly to the input terminals, is said to roll off acoustically between 10 and 12kHz. (With a 30gm combined weight for the main cone plus whizzer, the large Zu driver has a higher mass than, say, a full-range Lowther driver, and quite intentionally.)

The Essence's cabinet walls are all ¾"-thick MDF, with an extra baffle sheet of ¾" Baltic birch plywood behind the drivers themselves. Internal cabling is Zu's own stranded copper, and all connections are either cold-forged or made with solderless terminals: The Zu point of view, explained on their website, is that soldered connections sound worse than some alternatives. Input terminals are the increasingly popular Cardas single-knob clamp, designed primarily for spade lugs—another Zu preference—although bananas work acceptably well.

The Zu Essence stands just a shade over 4' tall and weighs 65 lbs: light enough that one person can inch it into place, heavy enough that it will stay there. The speaker is shipped using custom foam spacers in a two-piece cardboard carton, all of superb quality and apparently capable of surviving more than one trip: This is, indeed, a real company. Extras include threaded spiked feet for use on carpets—threaded blunt feet, for bare floors, are installed at the factory—a microfiber polishing cloth, removable metal grilles, and a thorough 14-page guidebook.

Installation and setup
With its claimed 97dB efficiency and 12-ohm nominal impedance, the Zu Essence is obviously designed for use with low-power amplifiers. I happily obliged, driving the review pair with my own Shindo Haut-Brion (20Wpc), Quad II (15Wpc), and Fi 2A3 Stereo (3Wpc), as well as a borrowed pair of Shindo Corton-Charlemagne monoblocks (25W). The Haut-Brion accounted for most of my listening: appropriately so, given that each of the amp's output transformers has only a single, 16-ohm secondary winding.

Ron Williams of Zu visited a few days after the review pair was delivered, to help fine-tune their positions in my room. Striving for bass extension, smoothness of bass response, and overall spatial perspective, we wound up placing the cabinets about 5' away from the wall behind them, and reasonably close to the sidewalls (footnote 3). Later, Williams used an Accuscan Strait-Line laser leveling tool (ca $30 from Amazon.com) to dial in the Essences' spatial performance, ultimately toeing-in the cabinets about 40° toward the listening area.

A few days later I measured the review pair using my Audio Control SA3050 spectrum analyzer, largely confirming the Essences' 5' distance from the front wall as optimal for bass extension—although I was able to smooth out some upper-bass comb-filter effects by increasing their distance from the sidewalls, to about 16". Only two signs of suboptimal room interaction persisted: a pronounced dip at 50Hz, and a broader but slighter dip centered at 250Hz. Bass extension was flat to 31.5Hz, with audible content at 25Hz; top-end rolloff was gradual and smooth, with no apparent weirdness.

The Essence's treble output seemed to vary with proximity slightly more than average, which actually worked to the speaker's advantage: its tonal balance and spatial perspective kept pace with one another quite well. Put another way: With the enclosures and listener close to one another, the amount of treble energy—generous but not overdone—was in keeping with the nearfield listening experience. Mandolins had a realistic bite, vocal plosives and consonants were pronounced, and so forth. When I moved the enclosures a greater distance away from me, the spatial perspective was more distant and the treble energy was concomitantly and believably reduced. There was none of the cognitive disconnect that results from listening to certain other (usually physically small) loudspeakers whose tweeters remain enthusiastic even when heard from a distance.

Listening
With the review pair positioned as described, the Essences sounded pleasantly up-front, a perspective made all the more enjoyable by their very generous spatial depth: Though slightly amplifier-dependent—unsurprisingly, amps with global feedback sounded spatially a bit tighter and smaller than those without—the soundfield was consistently larger than average for non-horn speakers. Inasmuch as the Essences required me to sit somewhat closer than I usually do, they tended also to sound grander and a bit more enveloping than the Audio Note AN-E SPes, which have been my reference speakers for some time. Big as it was, the Essences' soundfield seemed airier and less substantial than that of the corner-loading Audio Notes, although individual vocal and instrumental sounds within that field had fine body and delineation. (For their part, the Audio Notes had less in the way of spatial depth and image location, but more substance overall—and more of a sense that, no matter where I sat at my end of the room, over there at the other end, real music was simply happening.)

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Footnote 3: I placed the review pair against the short (end) wall of my 12' by 19' listening room. Although Zu suggests that a pair of Essences can also be made to work well along a room's long wall and firing across its shorter dimension, I know from recent experimenting that there's one place in my room where both record player and electronics seem to perform their best, and that position rules out a long-wall installation.