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Positive Feedback ISSUE 33
september/october 2007


zu audio

Definition Mk2 loudspeakers

as reviewed by Danny Kaey






Zu Audio Definition Pro Lautsprecher.

Nomad Audio Niagara amplifier, Yamamoto AS-08 amplifier, Quad II (original) amplifier, Brinkmann Vollverstärker, Brinkmann Fein phono, and a Rane PEQ55.

Slimdevices Squeezebox, ZeroOne Ti48 HD Transport/CD player, ZeroOne Ar38 DAC, Technics 1210 M5G, Zu DL-103 cartridge, Denon TU-460 tuner, Lector CDP-6 CD player w/ RCA Blackplates, ReVox H-1 cassette tape deck, Technics RS-1700 reel to reel w/ custom Tim d.P. electronics, Dolby 330 professional Dolby B noise reduction - custom Tim d.P. modification, and an AEG/Telefunken M15A reel to reel.

Full compliment of Kubala-Sosna Emotion and Fascination cables. Full compliment of Audio-Magic Sorcerer and Clairvoyant cables.

Townshend 5 tier seismic rack, Townshend seismic sinks (1x component sink, 2x Lautsprecher sink), Grand Prix Audio 5 tier Monaco Modular rack.



To be perfectly honest, I have been dreading penning this review for sometime. No, not because I am somehow at a loss for meaningful words: precisely the opposite – what do I leave out and not say! The Zu Definition Pros (the "old" model) have managed over the past year or so to realign my auditory universe (as well as those who have come to listen with intellectual honesty) in more ways then one. Oddly enough, apart from the cheerleaders at 6moons, hardly any mainstream publication has picked up on what I shall henceforth term the "Zu-Factor". Is it because the Zu crew is so anti-establishment? Is it because they are young (mid 30s and younger) and therefore automatically too inexperienced to be taken seriously? Is it because they play real music (non-audiophile) at trade shows, demos, and such? Is it because they don't play the marketing game of "mine is bigger then yours?" Apart from rampant educated speculation, I don't know the answer; what I do know is that indeed there is some sort of vacuum in the mainstream audio press regarding Zu, especially considering the stellar success they have had over the past few years: modestly beginning with their Zu Cable line and now culminating and coinciding with their recent name change to Zu Audio.


Earlier I mentioned the Zu-Factor—what is it you ask? I suppose it could be any one thing or a combination of many: fact is, Zu is cool. Zu is hip. Zu is good. Do you Zu? Zu breaks barriers: Zu's top of the line automotive finished full-range loudspeaker sells for $11,000. Zu's meat and potato (nearly full-range with an output available to mid 30s) Druid sells for (adjusted for an updated automotive finish) $3400. Zu products are made in America (Ogden, Utah). Zu offers a 60-day home trial, no questions asked, money back guarantee for any of their loudspeakers. Zu speakers just look cool (did I mention that already?)! Zu is based on sound engineering principals, not some whirl-world Twilight Zone 5th Element theory. Most importantly: the guys at Zu are honest, dependable, and hard working peeps. You dig? Read on dude!

The story so far…

In the beginning there was Druid. And Druid was good.

What the Druids do and do very well is perhaps most easily ascribed as dynamic realism and realistic tonality. Everything else, as they say, simply flows from those two pillars. While the Zu "sound" apparently remains as polarizing as ever (people either love 'em or hate 'em), I don't see how anyone could sit through a listening session and come out empty handed. Sure, they are not the most resolving speaker out there, nor are they as airy, open, and hyper detailed as my previous benchmark, the Marten Dukes. But very few speakers I know of can come close to what they pack in terms of dynamic agility, correct tonality, sheer power, and real imagery. In the end, every speaker is a compromise of some sort: what you gain here, you lose there. No speaker is all things to all people. You simply pick the one with the fewest shortcomings and enjoy that which gives you the most satisfaction. Conversely, ten engineers will give you ten different, though possibly equally intellectually honest answers as to what the optimal loudspeaker should be. Live, love, be merry, and enjoy your music. Life's too short.

Having enjoyed the Druid MkIV model for quite some time, Zu's co-conspirator Sean Casey and I agreed that it was time to move onto the final coup de grace: the Definition Pro, a product very much shrouded in mystery.

To make a long story short, the $9000 Pros were never really an official product for those of us interested in home audio fidelity. Instead, you had to twist the arms of Sean and his alter ego Adam Decaria to get a pair made. Why? Simple really. The Definition Mk1 and Mk1.5 are full range loudspeakers, with each having four actively powered 10" subs per channel. For most people, and under most circumstances, this was more then enough to handle your wildest dreams of full-range sound. They later added a volume knob on the Mk1 (subsequently all Mk1 were converted to Mk1.5 status) to provide bass output adjustment to meet your preference and room acoustics; however, the clever boys at Zu knew there was more to be had. A true full-range speaker (like the Definition) is a special kind of beast: bass frequencies are difficult to tame, let alone from a loudspeaker capable reaching, God's honest, 16Hz. We are not talking pseudo port activated "full-range"—no Sir: this is the real deal, the real McCoy. We are talking about a loudspeaker capable of pressurizing your room to levels you won't dare tell your wife, landlord, or neighbor. The caveat with that sort of 10 octave coverage is that you invariably end up with loudspeaker/room interaction problems. Sure, having an output level control for your subs is helpful and may even work very well under certain circumstances, but to truly nab the bull by the cohones would be to use an outboard EQ/crossover with separate amplifiers.

Fair enough you say, but let's face it: most 'philes aren't up to the knowledge required to set up such an elaborate system, not to mention its added cost and complexity. Hence, Zu covered their tracks by offering the Definition Pro version to a select group of peeps; call it the VIP club, call it expert audiophiles, call it engineers, call it what you wish. Fact of the matter is that having lived with these actively EQ'd and powered Definition Pros for almost a year; I simply can't see myself ever being without such a speaker system.

Druid is good, but Definition is state of the art; pixel-peeping sucks.

Anticipating the Definition Pros was like waiting for the hottest date of your life to show up. Seriously. I called all my friends and gushed over the prospect of what was to come. Hi-Fi is cool. Hi-Fi via the Definition Pros is the equivalent of putting on a 6-point racing harness in a Ferrari F430, setting the Manettino to LC (Launch Control), kicking up 6000 rpm, and pulling the right paddle shifter. What happens next can cause irreparable damage to your psyche. It is as if someone had strapped you inside the largest man-made slingshot; you get pushed inside your seat with a vehement force as you hurtle towards 60 mph in the blink of an eye—or a click less then 4 seconds. I'd say that is a fair description of what the Definition Pros actively equalized to 16Hz did for me. My downstairs neighbor must have called our landlord a dozen times complaining about various memorabilia falling off his shelves as I listened to Yello, Kruder & Dorfmeister, or Mose Allison at 110dB. Yep, I'd say that's about 3.7 seconds to 60.

What the Druids did well, the Definition Pro improved upon in spades, and then some. The then some was air, resolution and well, err definition. What they added to top-end of the Druids, was simply an even higher sense of acoustic realism and authentic auditory illusion. Since the Definition Pros have arrived, I laugh at some of these so-called "full-range" speakers out there. Full-range? Ok, but do they do 16Hz? Ooops. Didn't think so. Never mind 16Hz. Can you crank them to 110 on the decibel scale (provided you have the power, though at 101dB efficiency you will need a lot less then you think) without any sign whatsoever of compression: dynamic or otherwise? Can they, at the flick of your remote, portray those same images realistically at 70dB without falling apart at the seams like so many speakers do? In other words, are they capable of retaining music in its full glory, or are they simply the equivalent of "pixel-peepers" in the dark of the night when the lights are off and the Gremlins come to wake?

Pixel-peeping is my new favorite term. It exemplifies perfectly what so many 'philes chase and chase and chase some more. Music has become secondary: they want to hear the fart behind the guy in the 4th row, 7 seats to the left. They love the sound of cow's farting. Hey, a cricket makes noise too! Golly well—tell 'ya what bud, knock yourself out, 'cause music it ain't. Betty van Stumpsing. Beehhh who? What, you don't know Betty van Stumpsing? Man, where 'ya been? She's a sucker of a musician, but boy, I said BOY, do her farts sound good! Friends, Romans, countrymen, yes indeed pixel-peeping is the equivalent to never being satisfied with your camera's resolution. Pictures? Wait, you mean I ought to look at the picture? What picture? All I see is 24 tetra pixels and it ain't enough!

A Ferrari F430 for my living room

Well, I suppose one must come to terms with what one aspires to own, have, and want. I want a music system capable of making me believe I am driving that Ferrari F430 in my living room. Honestly, that's my idea of a Hi-Fi system. In due time I shall return to racing automobiles, but for now, music is what keeps me sane. The Definition Pros are loudspeakers that work for me in that sense: they are ultra-quick, ultra-dynamic, ultra-tonal, and ultra-cool. They have the optimal amount of resolution—they play my eclectic taste of music from classical to pop to rock with an equal fortitude and that certain sense of ease. I have heard speakers offer different perspectives of the same theme: more this, less that. And there are many great loudspeakers out there, but I challenge you to show me any one that has the qualities of the Definition Pros at $9000. Or at $20,000. Or $40,000. I am not sure they exist. Fact is that the Definition Pros are the highest performing full-range loudspeakers per footprint available—guaranteed.

Even so, there is no best loudspeaker, much less "world's best" as one manufacturer (there have no doubt been many before) recently claimed. It all boils down to personal preference. One visit to a live music session ought to show you how far away we are from the original if that's the benchmark you use. Having said that, improvements and further optimizations are always possible without completely throwing out the original concept. A new shock absorber here, a magnesium rim there, reprogrammed and revamped engine management, it all ads up to precious seconds being knocked off the lap clock. Thus, if you wish to keep all other things equal, you look for the recently released F430 Scuderia. It retains the stigma of the F430 whilst adding further significant performance improvements.

An updated Definition in the wings: a new reference?

Happy and content that this was it, an email from Dotore Casey came my way sometime in April of this fine year "call me ASAP. We need to talk…" Hrmm… Il Dotore asking for my audience in such a direct way, I dared wonder what this could be? "Hey Danny, do you want to be the first to review the new Definition Mk2?" Gulp, Gasp, Goodness and holy Gazonga, where's the damned oxygen tank when I need it? Umm say what? The Definition is getting an upgrade? "Well, truth is, the Definition has been around for a several years, and as is normal in a product's lifecycle, it has reached its end. A new replacement is coming your way." I immediately fired back with the usual suspect questions: "What's different, what's new and when do I get them?"

The answers came at different times during the past months, as if to build anticipation of what was to come. Fast-forward to the beginning of this month; a nice FedEx dude calls and says he has two large boxes for me. Definition MkII has arrived. Goodie, goodie, I can't wait to hook these pups up, strap my 6 point racing harness on and pull that paddle shifter (again and again and again…).

The nuts and bolts, meat and potatoes: ladies and gents, the Definition Mk2

The Definition Mk2 looks nearly identical in size and shape to the Definition Mk1/1.5/Pro. Unless you have both next to one another, you won't be able to tell the difference. But that's where the similarities end. Everything is new. Everything has been redesigned from the ground up. The emperor really has new clothes.

The previous generation's MDF has been scrapped in favor of something more rigid. Far more rigid. The cabinet is now made of a ¾" thick superstructured tuckernut/poplar/maple plywood core with a polyester/composite gel coated shell. The bass drivers (all four per channel) have been significantly upgraded, and as a result of this new superstructure, are now literally anchored to the cabinet. The highpass filter on the supertweeter has been upgraded, as have the former polypropylene capacitors in favor of the best paper/oil (Mundorf silver/oil, ran battery style) versions available. The bass array setup has been totally revamped and now actually features a separate section (smaller for the upper two, larger for the bottom two) for each pair of the four 10" woofers in the back. Perhaps most importantly, the Definition Mk2 is also the previous generation's Mk1.5 and Pro rolled into one. You heard right: the Def 2s have a built in 120-watt class A/B amp to power the bass arrays, yet can be converted to fully active status at a moments notice—provided you have the spare coin to do them right. You wouldn't want your F430 Scuderia running off 87 octane now would you? About the only thing retained from the previous generation are the superb Cardas binding posts. Oh and yes, the Definitions are still made in Ogden Utah. That's America for those of you out in Rio-Linda.

All in all, this isn't your modders upgraded loudspeaker. No sir, this is a complete ground up redesign with a goal of retaining the original's design perimeters. Naturally, this sort of thang doesn't come for free—considering the wherewithal, the price point has been raised to an insignificantly higher figure of $11,000, which now includes your choice of three glossy hand rubbed automotive finish colors (this alone was a 2k up-charge on the previous model).

Visually, the quality of the finish has been dramatically improved. Mine were delivered in (you guessed it) Ferrari glossy red, with custom twin 10" blacked out rims err… drivers. "Holy crap, they look stunning!" Was the first thing I said when I unpacked them.

Definition: redefined.

Within ten minutes of connecting the new fully burned in Definition Mk2s, I knew that the previous flagship's lap times had been reset by a new fastest lap. Take a deep breath and relax, the improvements are immediately noticeable. These center most noticeably on (you guessed it) dynamic realism and overall improved definition: midrange pep, top end extension, and resolution. Let's recap quickly: dynamic realism centers around the belief that if a loudspeaker can portray the intricacies of music from loud to soft, top to bottom, start/stop, it will therefore make music sound more real. Recall my comment earlier about live vs. recorded sound; the most identifying mark of a live performance is precisely that: dynamic range or realism. Not having to pass through a recording chain and subsequent playback chains the realism of an actual instrument playing before you is breathtaking.

With proper amplification behind the front main drivers and the rear woofer array, the Definition Pro was an already outstanding performer. Until that is you hear the Definition Mk2. Bass appears tighter, more integrated as a whole and simply more natural. The attack/sustain/decay relationship of a note has been heightened and refined to new levels. Yello's "Planet Dada" (Flamboyant mix) off their latest album The Eye, is a perfect example of such refinement. Whereas the Definition Pro gave you the whole picture, the Definition Mk2 adds a few more layers of refinement. The subterranean synth notes are much more integrated with the rest, i.e. there is now absolutely zero lag in the attack, sustain, and decay of the rear woofer arrays in relationship to the hideously quick and super fast front drivers. This was a major goal the Zu guys had set out to achieve. 0-60 in 3.5s? You betcha!

No matter what amplifier I put upstream, the very fine Brinkmann Vollverstaerker, a superb Luxman MQ88, my original Quad IIs, an Fi 2A3, Yamamoto or even the rather cute Luxman SQ100 NeoClassico, the Defs let each of these amps breath with their respective sonic signatures, strengths, and weaknesses et all.

"Ionization", off Varese's two disc Decca CD compilation, is another perfect example of how various improvements manifest themselves. The track starts off rather slow and distant, yet full of musical textures and information. This piece, written entirely for non-pitched percussive instruments, is an exemplary demo of Varese's technique. A piano here, a glockenspiel there, a sudden drum roll exploding dynamically; each of the instruments is layered with definition, realism, and almost surgical pin-point imaging. Simply stunning and a must have recording for anyone serious about percussion. The Definition Pros are somewhat vague and far less differentiating of this spectacle: think brute force vs. scientific precision. The glockenspiel for example, rather dominant throughout the performance, now appears to have taken on a new life; a relief like three-dimensional pictures unfolds in the far away aural landscape before you. If that's not pinpoint imaging and realism, I don't know what is! Similarly, the top-end extension, no doubt due in part to the new filter caps, appears much more refined, airy, and relaxed.

Male vocalists—or the total and utter absence of any crossover mangling in the hyper critical midrange—are a defacto dominant theme amongst all Zu loudspeakers. I vividly recall hearing Sinatra, Martin, or Cash for the first time on the Druids: simply lifelike, or more real sounding then I had ever heard before. What's better then a crossover dividing up the music amongst multiple drivers? The answer is no crossover and a single driver! Here again the Definition Pro was absolutely top notch. In my room, the magic trio (Sinatra, Martin, and Cash) never sounded more engaging and effortless. The Definition Mk2 improves upon that by further integrating—layering—the vocals and music. Everything appears in clearer focus while being more authoritative (real?).

If riding an F430 at breakneck pace through your favorite Malibu canyon road is the idea of an ultimate car control, then listening to Meeting by the River, a Kavi Alexander/Water Lily Acoustics recording must be the audiophile equivalent. The intricate interplay of only three or four instruments within the confines of Santa Barbara's St. Anthony's Seminary Chapel is an exemplary demo track for the Definition Mk2s. Transient responses are off the charts. The dynamic swings, multi-layered instrumental colors, and tones are a test for any loudspeaker, yet, the new Zu loudspeakers don't even begin to break a sweat. Perfect downshifts, you hit the apex and slam the throttle—until you are ready to do it again at the next turn. That about sums up the experience you get when the Definition Mk2s play this track.

Conclusion… wait… that would imply an ending: a new beginning, in a living room near you.

So far, so good, but guess what: the Definition Mk2s do have shortcomings—shock, gasp, awe! Well certainly, recall the following: a speaker, any speaker, is a set of predetermined compromises. There are speakers (my old reference, the Marten Dukes come to mind) that give you a truly clinical, what goes in must come, out performance. There are speakers that will sound more resolving in the sense that resolution is a multi-edged sword; not necessarily referring to resolution parse. While on paper that sounds like a great feature. In life it could be the opposite. Too much information sometimes isn't that good of a thang. Pixel-peeping anyone?

The Definition Mk2s are quite remarkable. They retain the essence that makes Zu great while adding on a layer of refinements not heard from the previous king. They are far more forgiving with regards to setup and placement; they marry the Pro model's benefits of extreme room integration with the Mk1.5's ease of use, high-fidelity, and all. They are the quintessential upgrade: you feel right at home, yet are immediately aware of their newfound guts and glory. It's like getting in the F430 Scuderia when you already own the F430. The story sticks: I verified and checked with an owner.

The versatility of the Definition Mk2s will further be expanded upon with the rumored Zu (designed and manufactured) integrated digital EQ and Hypex powered amplifier module. This module will essentially replace two more boxes from your set-up: the Rane PEQ55 parametric EQ and your choice of separate power amplifier. If tall tales of eight foot men are to be believed, this module will also contain an E.T. inspired calling home feature. Through the power of the internet, the Zu crew will be able to check your EQ settings and adjust them, if necessary, for better performance. That sounds like the proverbial icing on the cake. Think of it: fully integrated 10 octave wideband speakers with a footprint not larger then your typical monitor. No need to take out the extra mortgage on the house or touch the kid's college fortune cookie fund. The value and performance conscious 'phile has a new king to crown. Who's hosting the party? Danny Kaey

Zu Audio
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