Anyone listen to Zu Audio's Definition Mk3?

Definition 1.5 was a livelier speaker than Def2, and its tonal center of gravity was shifted toward the upper midrange compared to Def2. The downside of Def1.5 was the MDF structure and the "cabinet talk" resulting from it at high SPLs. With Def2, Zu dramatically reduced the cabinet talk of the Definition architecture, giving it even more useful dynamic range, but one of the costs of tuning out the glare in Def1.5 was the slightly overdamped sound of Def2 (only in comparison to the incredibly jumpy Def1.5). The supertweeter network was improved as well, to tune out some of the older speaker's false sparkle evident in the supertweeter's anomalies. Def2 went as high, but it just didn't have all the tickle that Def1.5 had, along with that speaker's very top end distortions.

Def4 resolves the difference completely. Def3 should mostly. All of the liveliness of Def1.5 is restored in Def4, and then some. And all of the discipline and accuracy of Def2 is retained, and then some. The speed and openness of the nano-FRDs coupled to the tonal illumination provided by the smoothly extended Radian supertweeter eliminates the dark-tilt evident in Def2.

Solid State amps on Def2 went a long way to lifting the trace darkness in its tone, as did objective tube amps with extended top ends and bursty dynamic traits, but now that character isn't just mitigated. It's gone from the Def4 design and should be very much reduced in Def3's Def2 roots as well, since the nano-drivers are significantly responsible for the change (not the Radian alone). Def2s upgraded with 2010 HO FRDs pretty much lost the Def2 dark tilt anyway, so consider the small Def2 "overcorrection" to be adjusted out regardless which upgrade path you take.

Phil

My only technical query re Def4s is that the sub bass is downward firing into the floor. I know this is an established practice since many dedicated subs work the same way, but it all seems counterintuitive. Can anyone put me right on the pros of such an arrangement?
Musicxyz, you are adamant that a quality cable choice must be made for good audio, and same make used thruout system, a statement I agree with.
The Def4s have internal Event wiring which with Neutrik Speak-On connectors form a continuous loom with the Event spkr cables.
Does this mean that you are going to switch to Event from your current choice, and by consequence wire your whole system with Event?
Marc

While I cannot comment on the practice of the sub bass downfiring into the floor, I think that there is an advantage of a single sub vs the rear-firing, split-tuned array in terms of articulation and cohesiveness. It also allows me to position the Def 4s close to the rear wall. Plus, Sean told me that this approach is a lot less time consuming and less costly to manufacture.

I agree with both Phil's and Musicxyz's comments that CDs just seem to sound better - more enjoyable, engaging, etc. Like Phil, I am listening to CDs that I have ignored for years. It is not just resolution, detail, and extension. . . it is that they just sound better.

Neither Phil nor Musicxyz commented on the other advantages of the Def 4s. . . the off-axis listening (it was not very good with the Def 1.5s, it was a little better with the Def 2s, it is a lot better with the Def 4s) and the way the sound seems to fill space (it is a big sound without being a loud sound).

I am curious whether Phil thinks that the Def 4s require as much power as the Def 2s to sound their best.

By getting short notes up sooner, there are many aspects of Def4 I haven't yet commented on. It's true that the sonic spray into the room is wider. For me, it was already excellent with Def1.5 compared to most floorstanding speakers, though less broad than with the better point-source standmount monitors. But I had very good off-axis response and soundstaging in my room with Def1.5, which marginally improved with Def2. Def4 is a larger improvement in the distribution of full-frequency sound and soundstaging over Def2 than Def2 yielded over Def1.5. This is a function of improvements to all three driver segments. The supertweeter upgrade easily obvious in this respect, but the stiffer/lighter FRD cones spread better as well, and the monocone sub-bass makes its contribution to more even room loading as well. But while Def4 delivers a big sound when appropriate, it doesn't impose a spatially big sound when the recording or performance doesn't warrant it. The soundspace scales up and down to the music appropriately, yet the room is pretty evenly loaded acoustically even at low volumes.

WIth respect to power requirements: Sean Casey said at the time that upgrading Def2 with the 2010 pre-nano HO FRDs made the speaker perform more like it has 104db/w/m efficiency. He didn't change the rating on the speaker, but said the power transfer improvement with the HO driver would nudge the speaker's apparent efficiency upward. He was right about the "apparent efficiency" part and that probably was enough to make some small amps that were only marginally sufficient before, acceptable to some people in some rooms. Certainly, Def4 has an apparent efficiency that sounds dynamically higher than Def2 in its original form. There are multiple contributors. First, the nano main drivers bring the known strength of the pre-nano HO drivers. The supertweeter does a better job of keeping up with the main drivers as volume rises without losing clarity. And the sub is both cleaner and more articulate for being one driver instead of four, but also the new Hypex-based sub-bass amp has more headroom and it's "faster." So the net result is that with the jumpiness of the Def1.5 restored and furthered without the cabinet talk, I think some people can be happy with a smaller amp than with Def2.

That said, I still do not think that a 2w 45SET amp is enough for optimum general use, and won't allow a Def4 owner to hear the full capabilities of the speaker. But if you really like true flea-power SET, you're more likely to be able to live within its limits on Def4 than on Def2. I think the Definition architecture, however, is optimally driven by 12w-30w SET tube amps or the very simplest push-pull tube amps, of which the prime example is the Quad II monoblock pair, or some of the 300B push-pull designs like Audion offers. Seven to ten watts 300B SET amps are quite serviceable IF it is a design that dispenses with the bass bloat common in ordinary 300B SET designs, but that's really borderline with respect to experiencing the dynamic life Definitions can deliver if your room isn't small, IMO. It's not that seven watts can't drive enough average SPL. You hear the difference in the ease with which dynamic spikes are handled by the available headroom.

Nothing about Def4 changes my view that the ideal amplifier for it is 20-30w 845-based SET or similar big glass triodes. Some 211 amps in the 15 - 20w range are quite good too. At the recent L.A. Zu house party, I heard the Melody 211 stereo integrated amp driving my Def4s, and it was strong, agile, articulate and beautiful.

However, for people who like the broad creamy torque of a really large solid state amp, I think Def4 is even more accommodating of their sonic signature. For solid state, the McIntosh quad-differential autoformer-output power amps are particularly synergistic with Definitions. Electrocompaniet amps work well with Defs too. Despite the efficiency of Zu speakers, their high power handling gives you latitude other HE speakers can't offer. Put a pair of McIntosh MC1.2kw or MC600s on a pair of Definitions, and you will understand what the sense of "unlimited power" into a crossoverless speaker can offer in terms of sheer dynamic ease. Not everyone is ready for or oriented to tubes. Counter-intuitive to expectations and similar to the effect I'm hearing with CDs, I fully expect that the Radian supertweeter will present the grain and sometimes hash in solid state amps less obtrusively than the older Definition supertweeter. But this also means that low power solid state amps like Pass Class A, First Watt and 47 Labs should sound more beautiful too, than they have in the past.

A reviewer who is getting Def4s dropped by last week to hear them on my SET amps and on Quad II, which is what he will be using. If you've read anything here I've written previously about Zu speakers, you know that I advocate going heavy amplifier quality with any Zu speaker, and have said in the past that Superfly powered by a great $10,000 amp will sound better than Definitions powered by the best $1,000 amp. Given the quality of some tube amps coming out of China and on the used market, that may be less true with Def4. New production Quad II monoblocks list for $3300 or thereabouts. THAT is a hell of a lovely sounding combination where the amplification is reasonably moderate, the design is simple and retubing costs are light. Quad IIs sound considerably more muscular into Def4 than Def2, in part because of the new speaker's 8 ohms nominal load against 6 ohms for the older version.

Overall, I think Def4 allows a wider range of amplifiers to put it in its sweet spot, but I still think the centerpoint for optimum match is high quality 845 or 211 SET, led by (in order) Audion, Sophia and with Melody coming on strong right on their heels.

Phil

Regarding the questions raised by Spiritofmusic:

The downfiring sub driver has several advantages, in no particular order: In Def4, the driver is bolted to a 1.5" thick machined aluminum plinth, plus it's a cast-basket 12" driver. Mounting the sub driver to an equally rigid rear panel would require a much larger slab of aluminum or alternate material to achieve the same management of the driver's motion energy on a more expansive panel. Additionally, by mounting the driver in the plinth, the opposite wall is small and stiff rather than tall and large, so cabinet resonance is more easily controlled. The cone motion can't rock the speaker cabinet, either. Then, consider that the soundwave is projected toward the floor, which is generally a stiffer, less resonant surface than is a wall behind the speaker, at least in American sheetrock-over-studs construction. And the downfiring sub can load the room radially and reflectively, instead of mostly reflectively in the case of the rear-firing sub array. And not least, the single 12" cone can speak with one voice rather than the inevitable blurring of detail that accompanies four drivers even if they are matched (my primary complaint with linesource speakers).

As for cable, I don't believe it's absolutely necessary to have a single-brand loom for your system. All cables bring specific characters and you may want to use them selectively to tune anomalies in specific areas of the system, but when you can find continuity within one line, that's good. My Druids system has early Druids that have been upgraded over the years to v4-08 status, but they are early enough to have the Speakon connector Zu originally fitted as standard, to preserver their B3 cable geometry all the way from the FRD to the amp terminals. Since those speakers also have the Cardas clamp for spades, I years ago listened to the comparison of Zu Ibis cables connected through the Cardas clamp and via Speakon. My Druids are internally cabled with Ibis. For me, the simple preservation of B3 all the way to the amp is audible and favorable, so I'm glad to see it brought back to Def4. Whether you chose the character of Mission or Event or older Ibis Zu speaker cables, I definitely advocate going with a Zu speaker cable via the Speakon for full B3 geometry.

That said, a friend or mine who had Def2s with HO drivers chose the excellent and really beautiful sounding Auditorium 23 speaker cables, which use low-mass bananas and are natural-fiber jacketed. I will hear his Def4s soon and will compare the Aud23 via adaptor, with Ibis B3 via Speakon and let you know the difference. Cables are the least urgent thing to get right.

Further, Zu cables have a common thread of neutrality running through them, regardless of grade, so there's no problem mixing Event and Mission, according to expense or choosing one over the other for portions of the system. My systems have Mission in specific places where that's the right interconnect for phono and getting three turntables with five tonearms and multiple transformers and phono stages in two systems wired up, Varial elsewhere, and Ibis to speakers. I even have some custom-made tonearm cables made from Cardas 33awg shielded wire in the mix. When listening, no one is looking to scrutinize the cable loom.

Phil