Zu Audio Essence Loudspeaker (TAS 212)

Equipment report
Zu Audio Essence
Zu Audio Essence Loudspeaker (TAS 212)

Zu Audio is a Utah-based loudspeaker and accessory company that was founded in 2000. The brainchild of Sean Casey (R&D) and Adam Decaria (Chief Engineer), each formerly of Kimber and Talon respectively, these entrepreneurs have assembled a business with a clearly defined identity and strong sense of direction. For proof of this you need to look no further than their mid-line Essence loudspeaker. Not the product of cookie-cutter, been-there-done-that design and manufacturing, it’s refreshingly plainspoken, almost severe—a monolith with no poetic aspirations. It’s not trying to resemble a rocket ship or a totem pole or an aircraft carrier. Its unapologetically blocky dimensions seek no softening from a well-placed curve or gentle radius. It’s just a big square slab of retro-loudspeaker, nearly fifty inches tall, that in any normal-sized room will not be ignored. Yet, in my listening room, bedecked in a soft, matte, avocado finish that made be crave guacamole every time I looked at it, the package somehow worked. It received nothing but nostalgic “oohs” and “aahs” from all who sat in my listening room, as if they recognized a kindred spirit from another time.

Appearances aside, the Essence is a high-sensitivity, hybrid-driver floorstander. Its key feature, central to Zu’s philosophy, is a large 10.3” full-range cone driver that covers the range from roughly 30Hz to 10kHz, reproducing all but the upper harmonics of the frequency spectrum. In one form or another this Zu-designed-and-built driver graces and grounds each model in the line. It uses a pulp-paper cone, which in turn is augmented by a 4” whizzer cone driven by the same, single voice coil. The top octave is handled by a transformer-coupled, foil-ribbon tweeter via a Bessel-based, second-order high-pass filter—the only electrical crossover component in the speaker. So, except for the top octave, the Essence is essentially a crossover-free single-driver system. The enclosure is a rigid combination of MDF and Baltic birch ply. Cardas’ patented cinch-type binding posts are a nice touch on the back panel. Zu Audio is a factory-direct company and its aggressive warranty and 60-day return policy demonstrate its determination to satisfy all customers.

Internal bass-loading is Zu Audio’s own design. Named ZuRG, for its co-designer Ron Griewe (RG), it comprises is a tall, high-density, foam-like pyramidal construction within the enclosure that widens from top to bottom and terminates above a slotted vent in the plinth at its base. This damps standing waves and controls progressively lower frequencies, reducing vent noise, and overhang artifacts that bloat or slow bass response. For Zu it’s a more effective solution than the conventional fiber-fill or constrained-layer approach.

A relative rarity in the high-end, Zu’s whizzer cone is a lightweight diagram concentrically positioned around a large, alloy phase plug, and driven by the main driver’s voice coil. It resembles something like a circular horn, and it operates purely acoustically. With proper implementation it aids dispersion and extends the top end and reduces the tendency of a large cone to beam. By virtue of its comparative lightness it also promotes quickness and transient agility. In principle it’s an inexpensive and expedient way to generate high frequencies without resorting to a second transducer and its attendant crossover circuitry.

The Essence’s 97dB sensitivity and 12-ohm nominal impedance mean that about the only amp—tube or transistor—that can’t drive the Essence is a broken one. That’s not to say is doesn’t appreciate a good, clean signal. Whether it was the PrimaLuna Premium Prologue integrated on the tube side or the ARC DSi200 on the solid-state one, quality amplification invariably stiffened the Zu’s spine in the bass and added transparency and liquidity in the treble.

The Essence offers a fairly wide listening window, but small frequency shifts suggested that window was a little more height-dependent than expected. To achieve the most even balance I felt that I had to sit up a bit straighter than I normally would¬. So if slumping into the couch is your preferred listening posture, you might want rethink this habit.

The calling card for all Zu Audio products is the big full-ranger. It’s Zu’s gold standard—a hard-charging extrovert of a driver from which all aspects of sonic performance follow. It produces a warm voluminous soundstage, a realistically scaled acoustic with near life-sized instrumental and vocal images. There’s a rewarding sense of dynamic thrust and impact as well—elements built on solid if slightly uneven mid-and-upper-bass response. With no crossover components, save for the high-pass on the supertweeter, and no multiple drivers splitting the critical midrange, the Essence achieves an alchemy of coherence and image resolution that called to mind the point-source ideal. Images were well-defined and locked in with assurance.

Zu will tell you that all its speakers are built around the human voice and, indeed, there’s a strong element of intimacy and energy in the way it reproduces vocals from the deepest baritone to the loftiest soprano. The midrange is responsive yet has a warmth factor that fuses nicely with the extension and suppleness of its bass. There’s an open, unobstructed wholeness to its midrange, a sense of effortlessness at any reasonable volume in a normal-sized room. Likewise the treble is well-lit and airy; however, even with an assist from the ribbon supertweet, don’t expect the “infinity and beyond” personality of an electrostat or premium dome. I also noted that the very high crossover point for the ribbon tweeter creates a smooth transition that effectively removes a common coloration that occurs when transducers of different materials, radiation patterns, or general design bump up against one another. Historically, ribbons and cone drivers don’t sing with a single consistent voice for this reason. For the Essence, the ribbon is outside the fundamental range of the orchestra and is only asked to blend in the purely harmonic range. And this it does well and unobtrusively.

Bass response is nicely extended in pitch and impressive in its lack of dynamic compression. The Essence plummets forcefully into the low 30Hz region, but rolls off quickly below that. Its sense of pace in these nether regions is somewhat easy-going, if not a bit woolen at times. An example would be the bass viols during the Korngold Concerto for Violin and Orchestra [Anne-Sophie Mutter, DG]—rich with resonance and immediacy off the bow, yet somewhat thickened and defocused as they descend in pitch. Whether this is due to a cabinet resonance or the loading design is difficult to say. It’s an issue that won’t get everyone’s attention, but I prefer more control.

In tonal accuracy the Essence can get unruly at times. As vividly detailed as vocals can be, timbres lack consistency top-to-bottom and low-level cues will often recede and assume a softer focus. Thus, as I listened to Norah Jones’ “The Nearness of You” [Come Away With Me, Bluenote], a couple of things came to mind. Her voice was slightly hooded and laid-back on the sung notes but over-detailed during the breathy decays. This midrange recession underscores a glint of brightness in the sibilance range, which adds emphasis to high-hat and other metallic percussion cues. Further, a strong male voice like Frank Sinatra seemed lifted slightly in pitch, shortchanging the weightier contributions of chest and diaphragm. Conveying a similar impression, piano harmonics were reproduced with greater intensity and ring and marginally less weight on the fundamental.

For me, minimalist crossover designs have a sense of speed and attack that make them stand apart from typical two- and three-way designs. In the Essence’s case, transient information is ricochet-immediate, with no trailing artifacts. Solo piano, in particular, exhibited terrific micro-transient speed. Beyond this attention to transient information, there was a delicacy of detail to acoustic guitar, mandolin, and banjo that communicated a greater sense of the human component¬—the finer gradations of volume and timing that make listening to the neo-Bluegrass music of Nickel Creek such s distinct pleasure. To be fair, there was also a hint of added sparkle in the upper octaves of these instruments, but that was easily forgotten after a few moments. Dynamically, the Essence is an unalloyed party animal. It gently prods percussions cues forward and snare drum thwacks land like grenades. Similarly the ping off of drumheads sound as if the skins were retensioned for crisper impact.

The Essence is a great lesson in the power of one. And much credit is owed the determined Zu keepers for pursuing the one-driver solution and delivering it with such value and mind-bending economy. For me, the Essence never failed to forge a strongly musical connection. But it also provoked me to consider the old conundrum about just what constitutes musicality and realism in a loudspeaker. Tonality hardliners will squabble that it misses the bull’s-eye in a couple of significant areas. Conversely, many will applaud Zu Audio’s more holistic approach. One thing we do know,¬ however, is that there's no such thing as one-speaker-fits-all design. The Zu Audio Essence really needs to be experienced to understand its unique magic. In the world of cookie-cutter audio, there's really nothing else like it out there.


Drivers: Ribbon tweeter, 10.33” full-range
Frequency response: 30Hz-40kHz
Sensitivity: 97dB
Nominal impedance: 12 ohms
Dimensions: 49” x 12” x 12”
Weight: 65 lbs.
Price: $4000 in standard finishes (walnut and ghost black); add $1200 for custom finishes.

3350 S. 1500 W.
Ogden, UT 84401
(801) 627-1040

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