Zu Audio Definition Mk IV, Marten Django XL, Audeze LCD-3. 

Einstein The Tube (pre-amp), Einstein The Light In The Dark (amp), Einstein The Turntables Choice (phono amp), Quad II Anniversary Gold Jubilee (mono blocks), darTZeel 8550 (integrated), Brinkmann Fein (phono amp).

Playback Designs MPS-5, Sonicweld Diverter 24/96 SPDIF/USB, Korg MR-2000s, Brinkmann LaGrange ('table), 2x Brinkmann 12.1" ('arm), Brinkmann RöNt (tube PS), Ortofon A90, Dynavector XV-1s, Zu-DL-103, ReVox PR-99 Sonorus modified, ReVox H-1, Telefunken M-15, 13" MacBook Air (late 2011), Drobo FS. 

Kubala-Sosna Emotion, interconnect, speaker and power, Einstein, interconnect, speaker and power, Zu Audio, interconnect, speaker and power.

2x HRS M3X isolation base, Townshend 5-shelf air suspended rack, Hannl Flüsterbär record cleaning machine.


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Positive Feedback ISSUE 66
march/april 2013


zu audio

Definition MK IV Loudspeakers

as reviewed by Danny Kaey


definition mk IV lodspeakers

Wow. It was September 2007 when PF published my last ZuAudio Definition Mk II review – that's like a month after the original iPhone launched. That's like a full 3 years prior to the iPad launching. What's that got to do with Hi-Fi or Zu Audio you ask? Not much, I'm just sayin'. So what has changed in the world of Hi-Fi? For starters, and speaking of Zu, they are now in their 13th year of business. Seems that not long ago the Zuguys where running around the country in style flashing the original Zu Druid to prospective buyers, defining their style and wares. Today, Zu Audio has the Union, Omen, Soul Superfly, Druid, Message, Definition, Dominance (their flagship), Undertone (subwoofer), Submission (you guessed it, an even larger subwoofer) and probably a few more yet to be disclosed loudspeakers in their lineup.

Common to all these models is Zu's proprietary, nay, legendary, 10" full bandwidth avec whizzer cone main driver (Zu FRD-HO), usually coupled to a high-pass filtered horn loaded tweeter assembly, or, as in the case of the Definition Mk IV, their latest Radian 850 based supertweeter. I highlighted supertweeter, because in this case, Zu is truly using a superlative tweeter not usually common to loudspeakers in the $5k to $16k range. While the Dominance utilizes a dual Radian 850 setup, that speaker also starts at $60k, depending on your choice of finish, thus isn't really in the realm of this review. Shoving a tweeter of that stature and quality (not to mention cost) into the Soul Superfly for example, is clearly an indication from Zu that they are now playing in the big league. Small potatoes these aren't anymore. Refried beans? Go elsewhere. Zu has grown up. Zu has become a dominant, if still somewhat esoteric player in the loudspeaker landscape that is 2013. Zu is bigger, bolder and better in every way.

Attending the latest group of Hi-Fi shows, Zu's rooms are now filled to the gills with customers both old and new, and one can no longer equate the Zu crew with audio's fringe. Music (real music, that is) is pumping, feet are tapping, heck even peeps from Stereophile, The Absolute Sound, and various other e-zines are now regulars at Zu. Who'd have thunk? Another sign of Zu gaining popularity is the barrage of emails I get querying me about their various wares, what amps to pair them with, how good they'll sound (like, seriously, what sort of question is that anyway?), etc. Love it. Hey, I guess people value my opinion.

Dialing back to the original premise that was the original Definition, prototypes of which I saw and heard at one of Zu's road shows circa 2004, the Definition was born out of Sean Casey's quest to build the best possible full range speaker in about a square foot of space. Pulling all punches Zu knew how to, the original Definition arrived with dual stacked 10" full band drivers up front, and a quad stack of 10" bass drivers facing the opposite end. Power was delivered via a clever setup of dual amping via a passive eq: one set of amps drove the main speakers, the other set the bass drivers. Clever, because you could dial in the speakers to pretty much any room, giving you ultimate adjustability over the bass output and most importantly, quality. After all, there's nothing worse than boomy 26" Dub style Cadillac monster bass on ‘roids. Heck, that doesn't even go with the whole Hi-Fi thang. But, I digress. The Definition Mk II (the model that stuck with me since that last review), upped the ante. A few dials here, tweaks there, allowed for even better bass and overall tone separation. A newly minted cabinet, with higher structural quantities, proved fidelity inducing long days (and nights) of audiophilia in casa Kaey. Added, was the bonus that in addition to being able to drive the Def's with separate power (still), you now also had the option of using the Def's built in plate amp avec modulation adjuster in a far more simpler, dare I say, elegant style.

Sure, some performance was lost in that game, alas, sometimes simplicity and integration trumps sheer guns of fire. Sigh. I will never forget that one fateful day in September (of 2007), when Sean, whilst on a visit to another customer, dropped by my house to "dial in " the Def's with all the usual room acoustics gear he'd tag along. A mic placed at ear level in my seating position, a Crown digital (true!) 2000 watter, a Dolby digital eq crossover sandwiched between the front and rear bass drivers was all it took for my bass levels to forever get sublimely challenged. Playing some such track—I forgot which one, though I think it was some bass sampler disc—I shall never forget the sheer power, grace, and solidity the image took on, never mind the wall shaking, pant flapping (literally) energy that was produced by this sonic aura, never again to be replicated with any other equipment. Eight ten inch woofers pack some serious punch. I mean serious.

Have I said Wow already? Simply put, that was cool. Well, years have passed, amplifiers have come and gone, setups have changed, I got divorced, rooms have moved, but the one thing that was always elemental, nay, fundamental, throughout the years was that pair of Zu Audio Definition Mk II's. What most fascinated me about the Zu sound was its immediacy, tone, life-like quality of being able to bring alive music, performers and instruments alike. All in a package about the size of a square foot. Power handling was off the charts, what with 101dB efficiency: care to run a Threshold T-400 mega-amp? No problem, make sure your power bill has been paid. Conversely, are 12w Quad II mono's your fancy? No problem, plug & play baby.

My latest efforts surrounding the quest for ultimate fidelity is circling back and forth between a DarTZeel integrated behemoth, said pair of Quad II Gold Jubilee edition amplifiers (sorry, won't ever sell those puppies), and an astoundingly convincing all tube setup (pre- power- combo) via EINSTEIN from Germany. Cabling ranges from Zu's own proprietary stuff to Nordost to Kubala-Sosna to EINSTEIN's latest mega-buck wires. Naturally, my trusted Brinkmann LaGrange, and most awesome of all digital playback units, the Playback Designs MPS-5 (avec USB-X) handle all of the various file serving duties. I mean if you didn't tell and show me there's better stuff out there, I'd be hard pressed to believe you. I still don't. This is about as good as it gets, plus, minus a few variations. Smitten doesn't begin to describe what sort of music I get out of this system.

If all ended today, right now, I'd be a happy camper. Make that a happy and smiling camper. Fortunately, things didn't and won't all end today, thus we live to fight for another one. Over the years, rumors and even more rumors, used to come up now and then that Zu was working on an all new Definition; that Zu was working on time travel; that Zu had discovered Warp drive technology. All joking aside, I usually sort of laughed those off, much as I do all the Apple rumors of this and that. You get my point. Things did take on a turn for the legitimate, when, after one summer night's phone call to Sean, he did finally spill the beans (as I slipped him a twenty. Ha! JJ): "Yes, I can confirm that we will be showing off the latest version of the Definition, somewhat skipping version 3 (not really, alas, more on that later), and going straight to 4. You will be most impressed as we have redesigned the entire speaker from the ground-up."

Shock. Gasp. Awe. Wait a second mister. You mean to tell me that there's something better lurking around the corner? Wow. So Sean, please do tell! Really, he didn't have much telling to do. At last year's Rocky Mountain Audiofest he delivered the goods, and boy, deliver he did. Before me stood an ever so slightly taller, larger, better looking Definition Mk IV. Painted in whack job awesome Maserati Blue, the sheer Gestalt of the new speaker was awe-inspiring. First, as mentioned, the Def IV did grow up in size—somewhat. Not to worry, it still fits well within Sean's parameters of "about the size of a square foot"; performance enhancing CAD/CAM models necessitated a slightly larger footprint, after all, the new speakers' have that much more internal bracing and solidity to deal with.

definition mk IV lodspeakers

Gone however, are the Def II's monster pack of quad woofers, replaced with one single, downward firing superwoofer, Eminence's LAB12. While at first I felt let down by this revelation, after all, how could one 12" woofer deliver the goods of four 10" drivers, my fears were unnecessary and uncalled for. The entire assembly, i.e. cabinet and woofer, are bolted onto a 3" thick cnc'd solid chunk of aluminum plate. If the Def II could ever have been considered a fly-weight, the Def IV clearly barks up an altogether different tree. Heck, it's not even in the same galaxy. Call it 160 lbs of stuff you'll be lugging around during setup. The entire structure is notably, I repeat, notably more solid, and dare I say better built. Gracing the front are Zu's quantitatively superior all new full range drivers, impregnated (behave!) with the latest DuPont wizardry, and that oh so special super tweeter. It's massive. You don't quite realize how tiny most other tweeters are until you gaze at the volume of the Radian 850.

Power for the subwoofer system has also been notably upgraded. Scratch that. Re-engineered is more like it. The UcD 400 based switch mode amp is now housed in its own, made of aluminum billet, enclosure, cleverly integrated into the base of the Def IV. Sean's always been a keen one for customer service. Well, I can't imagine a simpler system to service a customer. Something wrong with the amp? No problem, unbolt 6 hex-screws and voila, you can rock the party old school. Try that with a modern day computer, car, heck, toaster! You get my point? Each of the main drivers now also sport their very own custom designed Grieve enclosure, said to enhance, improve and otherwise make better sound from the front facing ten-inchers.

Overall, the new Definition Mk IV looks more elegant, cleaner, and perhaps even leaner. Fast forward a few months, and said Definitions are now firmly planted in my listening room, having displaced the previous heroes, the Def II's. While, of course, at the Denver show I spent quite a bit of time listening to the new super speaker, having them inside my own four walls makes for that much more of an engaging experience. Amped via the DarTZeel integrated, the sound was at once clearly superior to my long-term reference. I hate to use the phrase, but music was simply more there. Beginning with those silky smooth highs, expertly blended into the main driver, and ending with the prodigious bass output, I marveled at the overall improvements. Coherent, solid, engaging, determined, wide, deep, were all amongst the adjective I penned whilst listening to the first cut—whatever that was.

definition mk IV lodspeakers

Articulation, definition, resolution, and speed are also items you'd be hard pressed not to notice when playing back your favorites tunes over a pair of dialed in Defs. The Def IV's also seemingly disappear even more so than the old pair, which goes something like this: on select, hauntingly well recorded music tracks, say for example Trentemøller's "Nightwalker" off The Last Resort, the new Def's are now completely integrated into your room; closing your eyes, an electronic feast of melodies is painted across the entire dimensional space that sits before you. Granted, special phase gizmos and some such recording wizardry part of the recording do quite a bit of the job of creating such atmospheric effects, even so, the quality of the reproduction is greatly enhanced. Plucked beats, pops, and other such effects literally seem to appear from nowhere, everywhere. Even if Trentemøller isn't your cup of Early-Grey, everyone hearing it is left impressed.

definition mk IV lodspeakers

Whereas the Def II was somewhat prone to off-axis listening or even head movement fore-aft (say you want to get more comfortable in your Corbusier lounge chair), the new Definition Mk IV removes those boundaries to a large extent, certainly the head movement part. Now, lounging in my rockin' lounge chair no longer produces that tunnel vision. It's one of those things that you have to hear almost side by side; otherwise you'd not know it was there. Subtle, but meaningful no less. Still, the new Def's are very much directional speakers, i.e. don't expect 180 degree Panavision; they do have a very defined sweet spot, however large it is compared to the previous model.

Now, that bass. Whereas before the Def IV's arrival, you would have to spend considerable time, effort, and energy (not to mention money with the added costs) to get world-class bass in your digs, the new speaks make it all that much easier and dare I say customer friendly. Show of hands: who likes to futz with a parametric Dolby digital crossover in time, phase, and frequency domains? Who even has the know-how to do so anyway? Then there's the extra gear, amplifier, cables, etc. It quickly becomes a daunting task. Not everyone is Sean or has a Sean (Casey) nearby. He of course does it all in his sleep. He once made peace with an Amazon tribe by simply raising his voice to say "Hello." He once rode from Ogden to Las Vegas to Los Angeles and back all in 1 day. He is… No, wait, wrong commercial.

Dialing in room shaking, glass shattering, pant flapping bass on the new speaks is far, far easier. A parametric eq with slope, level, and phase adjustments sit all neatly within reach of anyone looking at the back of the cabinet. Clearly labeled, rocket science ain't required to figure out what all the knobs, dials, and switches do. Moreover, a manual explaining all the gizmos is naturally part of the package, and even so, a phone call to Sean will usually fix whatever's broken in no time at all. Now that's what I call customer service. Those 12" Eminence woofers are something else too. Long throw, massive magnet structure and all, each one of these will literally bring the roof down. A pair of them is barely legal. With the new Def's cabinet structure and loading, these dual 12" drivers will quite literally obliterate anything and everyone in their way. Pressurizing a room to clean dust off walls? No problem. The new Defs do it all and then some, but most importantly, with swing and style. No boominess, no fake inflated 80Hz dial tone, none of that. Augmented reality is what I label it. To those of you who doubt the necessity for such driver arrangements, many a story has been written discussing just how important infrasonics and subterranean frequencies are to music. Call it weight, call it extension, anything and everything benefits from having a capable full range system.

Case in point, Ravel's Piano Concerto in G. Of the five pressings I have, my favorite two are Bernstein's and Schweitzer conducted by Munch (Boston Symphony). The Bernstein, a recent reissue available on IMPEX Records, is the more melancholy of the two. Imagine a solo piano on stage, yet, without the proper speakers, that piano simply won't be painted in its full scale. The ability to reflect infrasonic information contained within a recording—even when an instrument doesn't scale to those frequencies—is, in my most humble of opinions, an absolute necessity. A simple flick of the bass amp's switch proves the point to anyone listening. Gone is the grandeur of the recorded space, the small, tiny inflections of Bernstein playing with the piano's keys—simply put, it's all that much more Technicolor, 4K high-def, real when your system is capable of full-range acoustics.

Naturally, the entire sense and scale of bass augmentation works seamlessly, without the user getting a feel for where all that bass comes from. Sign of the times. Boom-rats and brag-queens need not apply. Mine's bigger than yours. Oh really? Crank James Blake's "Limit to Your Love" and even Sean (of the Casey variety) cringes. Love it when you can shake up even the guy behind the scenes now and then. "Danny, I don't know anyone who plays music—at times—so loud." At a music party late last summer (at casa Kaey) guests a mile away were welcomed to the drowning beats of Fluxion. Neighbors called to complain: "Turn that #$@!% off!!!" Me, I was grinning ear-to-ear. Love to upset the norm now and then. Yep, Threshold T-400 and Def IV avec infrasonics is a party starter.

Alas, don't be fooled by the sheer monstrosity that can be the Def IV. No, revel in its inner tone as it reveals layers upon layers of music at more sane volumes. Saturday mornings at times I enjoy a cup of Joe whilst James Taylor fiddles around with his guitar. The boldness and life-like sense of Taylor setting up in front of you is quite a revelation. Same with Elvis. Ever heard Dream With Dean? Dean Martin's mile high accomplishment is quite the crooner's manifesto. A dead quiet pressing of mine spins the most awesome music—tone, timber, resolution, the sense of one voice is, simply put, quite nice. The Def's hallmark has always been the dual 10" wide band: twice the output, twice the resolving power, minus a few tradeoffs by virtue of the design (I doubt you'll ever notice). Having heard the latest Druid V a few months ago, I am still somewhat beholden to the dual 10" setup the Def has. Yes, the new Druid has definitely grown up—the old model's restrictions are now long gone; there's space, air, and plenty of upper band extension. No doubt similarities are due to both speakers utilizing the same Radian 850 monster tweeter. Perhaps Druid V and a dual Submission combo would rock my fancy—who's to say.

Back to the Definition IV. Have I mentioned the latest Zu main driver's ability to resolve mid-range detail to a far greater extent than the previous model? Whatever Zu and DuPont cooked up technology-wise seems to work. You say paper based drivers are a notion of the past? Not necessarily so, given the right amount of development and technology impregnation. It's old school vs. new school. I'm speaking of the latest Accuton ceramic / diamond drivers. Newer does not always mean better. Case in point, some other US loudspeaker manufacturer—reputable to say the least—switching out some such fancy material to a good ol' soft dome tweeter in their flagship. Did you read that? Flagship. Thus, trust me when I say that Zu knows what's up—Sean ain't no fool. Keeping the musical stash juicy and goosed up to carry Zu's trademark sound is something he's obviously very keen on continuing, no matter the model or price range.

There's a certain heightened sense of immediacy around the new Defs that begs you to keep jamming. Loggins & Messina's "Angry Eyes" off a dollar-fiddy copy I bought at Amoeba proves the point. Resolution, focus, and the driver's ability to unravel that much more musical detail is quite astounding—high fidelity? You bet. Bass notes—there's that bass again—are now that much more clearly outlined and the overall tonal integration, low to mid to treble region, is now even more seamless an experience. All hail the Radian 850. That tweeter seems to be doing just what Sean wants it to: add more quality and quantity at the top end without calling attention to itself. Oxymoron? No, high-end audio my friend.

Conclusion. That implies an ending. A purchase of a pair of Definition's is merely just the beginning of your journey into music nirvana. Is it better than XYZ? I'll say this: it is currently the best—more refined—version of the Definition series that began way back with the original model. That leaves us with the following missing link: what's a man to do? Sigh. In my opinion, the all new Definition Mk IV is really that, an all new, ground-up redesign of something that's familiar. In my Def II review, I stated that it (upgrading to the Def II) was analogous to bumping the Ferrari F430 to the higher spec F430 Scuderia. All's familiar, you know the roads = music, alas, you want a bit more roar to go with it. Well, the Def IV is not only a Scuderia model, but also an altogether new level of accomplishment; lets call it the next model up, the F12 Berlinetta. Sorta, kinda, what all these car dudes do all the time—every few model years the previous model gets bumped up to an all new experience, while the model below now replaces that version. Confusing? You bet. Look at the venerable Porsche 911. Nothing in common with a mid-80's 911 is there? You get my drift.

Purists and old school Zu fans may feel the pinch and question Zu's overall direction—I say all ahead forward, no looking back. Well done Sean and team, A+++ Danny Kaey

Definition MK IV Loudspeakers
Retail: $12,800 a pair

Zu Audio