Definition 6

Reviewer: Srajan Ebaen
Financial interests: click here
Main system: Sources: Retina 5K 27" iMac (i5, 256GB SSD, 40GB RAM, Sonoma 14), 4TB external SSD with Thunderbolt 3, Audirvana Studio, Qobuz Sublime, Singxer SU-6 USB bridge, LHY Audio SW-8 & SW-6 switch, Laiv Audio Harmony; Active filter: Lifesaver Audio Gradient Box 2; Power amplifiers: Kinki Studio EX-B7 monos & Gold Note monos on subwoofer; Headamp: Enleum AMP-23R; Phones: Raal 1995 Immanis, HifiMan Susvara; Loudspeakers: Qualio IQ [on loan] Cables: Kinki Studio Earth, Furutech; Power delivery: Vibex Granada/Alhambra on all source components, Vibex One 11R on amps, Furutech DPS-4.1 between wall and conditioners; Equipment rack: Artesanía Audio Exoteryc double-wide 3-tier with optional glass shelves, Exoteryc amp stands; Sundry accessories: Acoustic System resonators, LessLoss Firewall for loudspeakers, Furutech NCF Signal Boosters; Room: 6 x 8m with open door behind listening seat; Room treatment: 2 x PSI Audio AVAA C214 active bass traps
2nd system: Source: FiiO R7 into Soundaware D300Ref SD transport to Cen.Grand DSDAC 1.0 Deluxe; Preamp/filter: Lifesaver Audio Gradient Box 2; Amplifier: Kinki Studio EX-M7; Headamp: Cen.Grand Silver Fox; Loudspeakers: MonAcoustic SuperMon Mini + Dynaudio S18 sub; Power delivery: Furutech GTO 2D NCF, Akiko Audio Corelli; Equipment rack: Hifistay Mythology Transform X-Frame [on extended loan]; Sundry accessories: Audioquest Fog Lifters; Furutech NFC Clear Lines; Room: ~3.5 x 8m
Desktop system: Source: HP Z230 work station Win10/64; USB bridge: Singxer SU-2; DAC: Sonnet Pasithea; Headamp: Kinki Studio THR-1; Speaker amp: Crayon CFA-1.2; Speakers: Acelec Model One Headphones: Final D-8000 & Sonorous X, Audeze LCD-XC, Raal-Requisite SR1a on Schiit Jotunheim R
Upstairs headfi system: FiiO R7, COS Engineering D1, Cen.Grand Silver Fox; Headphones: Raal 1995 Magna, Meze 109 Pro, Fiio FT3
2-channel video system: Source: Oppo BDP-105; All-in-One: Gold Note IS-1000 Deluxe; Loudspeakers: Zu Soul VI; Subwoofer: Zu Submission; Power delivery: Furutech eTP-8, Room: ~6x4m
Review component retail: $25'000/pr

Complete bandwidth on a foot². That's been the ambition of Zu's Definition since my 2005 review of the Mk1.5 conducted in Taos, New Mexico. Aside from the now signature MTM array of the equally signature 10.3" whizzer-cone widebanders, the first purely passive Definition sported four 10" rear-firing woofers in a cab about up to the elbow so no taller than the Zu Druid to the right of our chrome-domed model.

In its 6th incarnation, a single now active woofer has migrated to the bottom front whilst the rear sports a floating terminal plate for Zu's so-called Griewe loading. For the first time ever that orients vertically rather than uses the floor with a fixed or variable gap as the Druid still does.

The only 'print' review I found on Definition 6 is by ex contributor Michael Lavorgna. He loved it so much as to award it his Favorite distinction shown in the above banner. Such solitary coverage seemed a peculiar state of affairs for Zu's flagship speaker. If Sean Casey had a set in Europe, perhaps I could reload? "We would love for you to give them a go. We don't have a set in the EU. Let me know what colour is interesting and we'll get a set built."

Given that the colour should be something he could resell, I sent Sean this photo of our listening room. Could he pick a blue that would look good and have popular appeal beyond its stay in County Clare? Though his Soul 6 usually occupies our TV rig, I'd recently set it up in our main system to welcome an in-bound 10wpc FirstWatt SIT4 amplifier. Low-power amps are for high-sensitivity speakers. It's a fringe breed where Zu has some of the least fussy most carefree options I know of. Whilst the SIT4 would have flown the coop by then, I'd still have a SIT3. Yet Zu's hard-hung widebander built upon a pro-audio platform is a very rugged customer. It does equally well off high-power amps, even class D. Our 250-watt class AB 2.5MHz Kinki Studio EX-B7 monos above are on that task force.

With nearly 20 years since my first encounter, Definition has grown up a wee bit. It's still on the same footprint but now 137cm tall. The Eminence LAB-12 woofer still faced down on the IV precursor. The 6's line-of-sight orientation should increase shockwave impact of low-bass transients. With the vertical 'acoustic impedance adaption' scheme now on the widebanders, their response reportedly extends to 35Hz. The active sealed woofer's coverage has shrunk to just 1st-octave duty.

The cabinet construction too differs from the original by consisting of thin-wall Okoumé ply. Lower mass stores less energy. Lower weight also ships and manoeuvres easier; though with all the driver magnets and electronics still amounts to 115lbs. The widebanders too are radically different. As the below photo from Michael's review shows clearly, they're now dual-concentric sorts repurposed from Soul 6 so with tweeters down their throats. That makes the extra tweeter between them truly a 'super' tweeter. We also appreciate the black-trim option which against this mirror-gloss white lacquer of Michael's samples creates higher contrast than the natural aluminium. Between the trim, bolt and paint/veneer cab options, Zu give us lots of accessorizing rope. Sean will supply whatever we request but isn't in the marriage counselling biz. Best check with your interior decorator before hanging yourself with lime green in the dog house?

Definition 6's Hypex 400-watt UcD v5 class D plate electronics mounted on a suspension include rotary controls for volume, low-pass frequency, parametric EQ gain/frequency plus phase. Single-wire 5-way binding posts plus a parallel SpeakOn for Zu's alternate wiring scheme, a power inlet and on/off toggle with red LED complete the accoutrements 'round back. The floor sees integral self-levelling flat footers. It's a tidy build that celebrates classic rectilinearity. No swooping curves, Avalon facets, multi-segment Wilson stacks or Soul 6's truncated pyramidics here. Definition 6 is an unapologetic box speaker whose trim rings sit proud of the baffle. Versus purist single-driver widebanders, this six-driver triple-tweeter affair is decidedly out of wedlock.

But it should also shock those puritans on raw bandwidth and SPL like a tattooed Hell's Angel rumbling into town on his chopped Harley has them place their daughters on early curfew. Why is it that gals always eye the bad boys? Kidding aside, Definition 6's machismo on loudness and infrasonic potential is hard to argue away. That leaves the usual curiosity whether for quieter types and more acoustic genres, the big Zu still has that 'it' factor it's virtually guaranteed to pack for raves.