from 16,900.00

Definition Mk.IV distills everything we’ve learned from creating our flagship loudspeaker, Dominance, into a loudspeaker within reach of mere mortals.

Just take a look at the material content in the Def. IVs and you start to wonder how Zu does it for the price…. As I said, $16,000 is hardly pocket change, but it’s around half what you might expect to pay for a speaker system with this bandwidth from other sources. Even the bigger producers like B&W (the 800) or KEF (the Blade), with all their economies of scale, can’t get close to that sort of price/performance balance—and definitely not in a speaker this efficient and versatile. As a speaker whose ups coincide precisely with so many other speakers’ downs, it may or may not be your cup of tea. But for those who get what the Zu is all about, I suspect that once heard it’s an experience they’ll never forget (or forego). —Roy Gregory / The Audio Beat

I don't pretend this is a neutral review. The Zu sound captivated me from first listen and continues to bend my ear. A guilty admission? I like to skip to the end of reviews. It misses all the actual content but ultimately I want to know the observer's judgment on the subject. For the similarly inclined, I like these speakers. A lot. I cannot think of another that I would trade them for. For the rest willing to persevere a long missive on the subject, these speakers deserve your attention. —Mike Smith / 6moons

The Zu Audio Definition Mk. IV speakers kicked butt! They had the power to physically connect the listener with the music. These speakers don't just play loud, they let you feel the music's power in a way that few high-end speakers ever do. They just sounded better and better the louder I played them. —Steve Guttenberg / CNET

The new Zu Definition Mk IVs sounded huge and pumped so much musical energy into the room the good vibrations carried all the way into the couch I was sitting on. A musical massage and a nice reminder that this is all about music which all about having fun. — Michael Lavorgna / AudioStream

Zu has always put bang for the buck into every product it has made, and Definition [Mk.IV] is a very visible expression of this design philosophy. Expensive? Sure, but consider the competition’s and you can see the values inherent in Zu. Sean brought the big Zu Definition Mk IV. This thing is a marvel—101dB/W/m sensitivity, 8 Ohms, and clean extension all the way to 14 Hz, courtesy of its built-in subwoofers. To me, the new drivers have kicked up the sound quality a notch or ten, and on this new Definition, there is an effortless, powerful feeling that no amount of wordsmithing on my part is going to make you believe. —Steve / Enjoy The Music


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Sporting our new nanotech full-range drivers, the fabulous Radian 850 based tweeter and our Event cable. It uses our Zu-Griewe acoustics technologies for the full-range drivers, and cabinet engineering that addresses noise and framework function across all fronts: materials, structural, bonding and building technique. The resulting combinations of engineered plate, hardwoods, damping compounds and metal alloys create a very inert structure.

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Definition [Mk.IV] The Audio Beat by Roy Gregory

Definition [Mk.II] Six Moons by Mike Smith

Definition [Mk.IV] Positive Feedback by Danny Kaey

Definition [Mk.II] Positive Feedback by Danny Kaey

Definiton [Mk.IV] AudioStream by Michael Lavorgna

Definition [Mk.IV] Part Time Audiophile / Scot Hull / Deep Show Coverage



The Old & New Definition

Old Definition’s rear-firing sub-woofers are replaced with a single massively motored 12” subwoofer driver, mounted on a super rigged, machined-from-billet 2” [50mm] thick block of aluminum, firing straight down into the floor—this is powered by our new deep bass amplifier built around the highly regarded Hypex UcD 400 module. This new on-board subwoofer amplifier system is not only as good as it gets in quality power, it also provides transparent filter processing of deep bass signals, most of which are user adjustable so you can dial-out room modes without compromising the analogue integrity of the music fed from your main amplifier. These components, and the sophisticated cabinet, work together to deliver what we genuinely believe to be the state-of-the-art in any loudspeaker south of $40k. It’s hugely dynamic, massively sensitive, capable of handling high power if you really want to die young, and so wonderfully, gloriously coherent, unflappable and downright true to the gorgeousness of music that we might as well retire now and go home.

The most visible change for Definition Mk.IV is the machined aluminum plinth and subwoofer assembly. And while the cabinet size and shape look very similar to previous Definition models, the Mk.IV cabinet design solves resonance and baffle issues in a completely new way, focusing on structural and materials engineering and only using weight and mass where useful. The substructure is a 30 degree raked dual wall superstructure that solves material resonance and acoustics issues through elegant design simplicity. The baffle is the most unsound section of any loudspeaker cabinet, yet it’s the portion of the cabinet with the greatest impact on fidelity. With Definition Mk.IV we use the massive tweeter assembly as a stressed member of the framework, compressing 10 pounds [4.5kg] of 1-3/4” [38mm] thick steel alloy and 1-3/4” [38mm] thick billet 6061 aluminum to constrain the cabinet core right between our two full-range drivers, exactly where all this mass and strength will do the most good. The cabinet core material is a combination of engineered and solid woods. Joints are first mitered then strong-backed. The plinth / bass assembly is bolted into the cabinet’s superstructure to realize a structurally strong, well-damped cabinet without the end result weighing a ton of bricks.

Points of Engineering & Performance

Zu nanotech full-range 16 ohm drivers parallel-wired presenting an 8 ohm system impedance to the amp (32 ohm latent option for amps needing such a load e.g. OTL)

  • Radian 850-based tweeter assembly (if there’s better... we haven’t found it).
  • Completely new cabinet design using expanded materials pallet.
  • Zu-Griewe acoustic design principles applied to internal damping.
  • Event B3 based cable harness.
  • ZuB3 interface via speakON 8-pole.
  • Hypex 400UcD V5 based internal bass amplifier.
  • User controls and parametric tuning of deep bass.
  • Machined aluminum enclosure for electronics.
  • Engineered for in-field serviceability.

Definition Mk.IV is real high-fidelity, a sincere expression of our musical values—of what we create and build at Zu. You can see the strategic use of the mixed materials pallet, judicious use of silver in the cabling and high-pass network, and the uncompromising and intense focus given to all the drive units and the way in which they work together as a whole and interface with the cabinet—and how the whole loudspeaker system works within the room.

Like all Zu products, Definition Mk.IV is centered and weighted around the critical human voice (A1, 55Hz, through A6 and all the possible harmonics, to approximately 10kHz). Serving this critical region of tone is our nanotech 10” paper cone substrate-based full-range driver—the same developed and used in the Dominance. So with tone, texture and definition realized in the meat of the range, we’ve set about redefining the frequency extremes with Definition Mk.IV—in very real terms as evidenced in the driver selection, and demonstrably evident to your ears, chest, and soul.

Third Generation Zu-Griewe Electroacoustics Loading

Zu-Griewe driver / cabinet / room loading technology as applied in Definition Mk.IV exploits the high efficiency full-range drivers’ bass performance. This affords a seamless integration of the subterranean tone and textures reproduced by the system’s subwoofer.

Zu-Griewe technology was developed by Ron Griewe and Sean Casey, with its beginnings in competition two and four-cycle motorcycle engine exhaust systems for improving power output, with increased bandwidth, while reducing noise and sound pressure levels over convention. More on the Zu-Griewe tech can be found in the FAQ section.

New Nanotech (Zu103ND/G1-16) Full-Range 10” Driver

This new Zu driver delivers stunning attack, shove, resolution and bandwidth—as they should, being lifted straight from our flagship loudspeaker, Dominance. Features include a maximal motor for expanded dynamic contrast and reduced harmonic distortion; a lightweight neutrally hung voice-coil assembly featuring a paper/Kapton former; a linear in-line layup of the inner cone for best resolution of detail; a diamagnetic shorting assembly for dynamic damping of the moving mass when playing at concert levels; nanotech paper cones designed to support wide bandwidth; and a billet phase cone with concentric maximal length sequence diffusion for smooth high frequencies. All this is anchored to a heavy cast aluminum alloy frame with overbuilt bonded and riveted yoke/magnet/top-plate assembly.

In 2004 we began to experiment with cutting-edge DuPont nano-engineered coatings and solids. The initial reasons were to realize the best possible gloss finish and one that would also be far tougher. These nanotechnology engineered liquid solid ceramics, fibers and synthetic resins performed as promised—so naturally we got busy experimenting on driver applications. Here’s what we’ve achieved: the driver’s cone is a paper pulp substrate, processed with a liquid solid matrix utilizing several nanoengineered materials. Some key components and compounds include: nanosphere ceramics, synthetic epoxy, cristobalite, plus the use of amorphous fumed silica and aircraft dope. The nano materials and application process reduce weight and increase strength and propagation velocity without incurring any sacrifices in damping. The end results are stunning—our new nano-sanctified full-range drivers sound dramatically better than any previous generation Zu FRD. Expect to see a lot more of them!

We continue to watch and experiment with new fibers and mats as they are very promising, especially what’s being done with buckypaper. For us however a tone-promising pulp-free combination of these new materials has not yet been identified. Nothing has proven to be as well behaved as natural fibers. There’s just something about paper. Its balance of strength, propagation velocity and damping all contribute to that tone, texture and fidelity we pursue. But add the right combination of old coating technologies plus nanoengineered materials and adhesives... paper maintains its advantages well into the 21st century.