Anyone listen to Zu Audio's Definition Mk3?

Comparisons with the 1.5s and the others that came before? Getting the itch; again......
I have the Def2 with the new flagship drives installed. Bought them from a member that heard the Def4 @RMAF and had to have them.

What I have kicks butt and am told the 4 will wipe the floor with the 2. The 3 is a Def2 sent ba k to Zu for the suPer upgrades. The 4 is their new model with down firing bass drivers.

I believe they will sell you the new drivers to install in your 1.5. Will make you happy for the next 5 years.
my mistake. I meant the Def4s. The new drivers you're talking about in my 1.5s? Happy for the next 5 years? NEVER going to happen. Knowing the Zu boys, the Mk4s (love a down firing woofer) will be amazing. I've been itching to find someone who has them, or someone who has had a critical listening time with them.
Hi Warren. They just debuted a few weeks ago at RMAF. The first shipments are probably just being received and I doubt anyone outside of Zu has spent more than a few hours listening. I too would love to hear the comparison. Maybe Glory can expound on the improvements that he has noted with the updated Drivers on the Def 2's?
I received my MK4s 10 days ago. I started with the 1.5, graduated to the 2.0, and now the 4.0. As much as I liked the Def2s, the 4s are a totally different speaker. The only similarities are in size (virtually identical to the 2.0) and looks.

The engineering is amazing. (1) The integrated amplifier can be unscrewed and popped out for service if necessary. (2) Similarly for the bass driver. (3) The aluminum base that supports the downward-firing bass driver is a work of art. (4) The Neutrik Speakon connector preserves the geometry of the cabling and accommodates a selection of connectors for each different type of speaker termination. (5) Bass can be tuned to the individual room. Etc. Everything has been thoroughly thought out.

The highs and lows are more extended. Deep organ notes are palpable (when appropriate). Resolution is better, but the sound is also smoother, more organic, and even a little more dynamic. The soundstage is deep and wide even though they are within 4" of the back wall. Off-axis imaging is amazing; maybe it is the way that Sean set them up on my 24' long wall, but the image does not change whether I am between the speakers, sitting in front of one of them, or standing against one of the side walls. And yet, everything that I liked about the Mk2s is still there. The sound easily fills my living room and the main living space of my house without a change in tone or quality when I am in a different room. I have listened for hours without any fatigue. Truly amazing.
Gsm18439's impression pretty much mirrors my thoughts on them. I have owned the 2's and had the drivers updated to the nano drivers (now speakers are owned by Glory) and that was a significant leap forward in terms of transparency and dynamics while retaining the fundamentals of Zu sound. I spent many hours listening to the 4's after show hours at RMAF and absolutely had to have them after spending enough time dissecting them. For any Definition 2 owner, it is a must have if you can afford them. The bass integration with the downfiring sub vs rear firing will make for much easier integration. More importantly, the bass is so tight, articulate, and palpable compared to the 4 driver array in the 2. It may have been the best bass I heard at all of RMAF. The cabinet is also damped better and has a very solid "thud" when you tap on it with less resonance. The nano drivers are absolutely spectacular and if you can't swing the upgrade to the 4, it's definitely worth the $3500 to upgrade to the 3. The bass amplifier is also much improved both from a modularity standpoint, but also from it's dead silence compared to the hum I heard from the 2's amps. Although it looks like a Definition 2, the only similarities are the spiked feet and the Zu logo. Everything else has been redesigned and this product is a revolutionary, not evolutionary product. When I went to RMAF I had absolutely no intention of upgrading to the 4's but after hearing them, I would have sold a kidney if I had to. I wouldn't have believed the level of performance enhancement of the 4's unless I heard them for myself. I am counting the second until my pair arrives!
As I recall, Zu used split tuning of the four rear firing drivers. While it might have had advantages with that particular configuration, it does not compare to the new single downward firing driver.

The great off-axis imaging (it really does not matter where i sit or stand) as well as the ability to position the 4s within inches of the rear wall were unexpected benefits.
Any more impressions guys? Or comparisons to other Zu speakers?
Zu's facebook page has photos of the new amps going into the MK3
Hi everyone, as a Def Mk 2 owner I am moving towards upgrading to Mk 4 status. Can those who have heard the Mk 4 comment on the improvements in treble quality with the radian 850 tweeter replacing the previous horn unit, since I feel this was most lacking in my room with the Def 2's. Regards
Def 3 is in the house!

Will post back after some time, but if first impressions are worth anything, this is a huge step up over version 1.
Hi Ton1313.....what are your initial impressions?
I recieved my MK III's about 2 weeks ago. Traded a pair of Presence for them. My initial impressions are the dynamics are fantastic . At high levels they seem to be coasting along where the Presence seemed to be pushed to their max, didn't think that at the time and liked the Presence a lot and still do but these just take it to the next level. Their imaging is great, totally disappearing. I still need to do some experimenting on toe in and tilt back. I hope to be able to widen the soundstage. I have some tough room obstacles. As I said I really liked the Presence,but these just improve on everything.
I was fortunately not to far off the path of ZU's recent cross country tour and was able to have Sean and Christian personnaly deliver and set them up. They arrived later than expected and than ran into some unforseen technical problems (a long and funny story) We didn't have music until well past midnight. We were back at it early the next morning, they not leaving until I was totaly satisfied.Yes I am a big ZU fan but only because of my experience with them and the MUSIC of cource. Their customer service is second to done!

Just noticed there is a promo pair on ebay now

Those Def IIIs in Anthracite on Ebay were my Def2s, now upgraded. I moved to the new 4s recently.

I can personally attest to the amazing condition---there is not a nick, scratch, mark on either speaker. They are only 2 years old as well.

and yes, the Def4 is a large upgrade, as it should be!
I was also on Sean & Christians tour path. They tweaked where I had them placed initialy, and we then messed with toe in and tilt. We found that they sounded best in my rig, with 1/4" tilt from front (higher) to back (lower). Some minor adjustments to the factory settings on the amps, and the initial listen after set up is completely amazaing. The presentation of the performers emotion is now very tangible, and just captivating....

Note: also using the Zu Event cables with their B3 connector for a direct signal path. I had this connection type on my original druids, (Version 1 - way back), and the connection type does make a noticable difference, as I did A - B back then with 2 sets of identical Zu cables, the only difference was the terminations.

That being said, I had to go out of town after they were set up, and did not have much time for further listening.

I just got back today, so I need to do some more critical listening.
I have my Def4s. I'll be posting a review in a few days, with comments relative to Def 1.5, Def2 and Def2 w/ HO drivers.


Waiting for your thoughts.
Have quite a few more hours listening since my first post. Happy with the soundstage now, the overall sound just keeps getting better the more time spent listening, having a hard time ending a listening session. Im using somewhat modest equipment, Melody I2A3,Zu Event cables,Cambridge 840c,Zu Wylde interconnect.
I have an interest in Zu speakers but do not know enough about cable connections to know if I can use my Belden banana plug cables that were placed under the carpet when the house was built.

Can anyone help? I have seen a picture of the rear of the Essence and cannot determine if I would have to re-wire.
If you have any questions such as the issue of connectors, talk to someone at Zu. They are very good about answering such questions. FYI. . .
Pretty easy to re-terminate. You don't even need to solder, you can even get self terminating connectors, set screw connectors, etc.

In my experience, bananas work very poorly with all Zu speakers. The mechanical quality of contact is just barely acceptable.
If for some reason you do not want to change the banana plugs, there are banana plug-to-spade adapters/converters. I used them with my Def 2s. The new termination scheme of the Def 4s is more flexible so I no longer need them ... if you are interested.
Hi, as owner of Def2s considering upgrading to 4s, I'm most interested in new owners' opinions, esp. 213Cobra who has always had intelligent things to say about Zu.
Currently running my 2s with SpatialComputer Black Hole bass attenuator, and it has so evened out bass integration issues in my room that I really need to be convinced the 4s are not just an evolution from the 2s but a major step up.
So, c'mon all you Def4 owners, what do ya think?!
I, too, am curious about what Phil has to say. But to me, the Def 4s are a major step up. Even though they look and are sized like the Def 2s (a look that I like and a size that I can live with), everything is new. Here is an embelished version of what I wrote at the end of October after getting my Def 4s 10 days previously. I have not changed my opinion. . .

The engineering is amazing. (1) The integrated amplifier can be unscrewed and popped out for service if necessary. (2) Similarly for the bass driver. (3) The aluminum base that supports the downward-firing bass driver is a work of art. (4) The Neutrik Speakon connector preserves the geometry of the cabling and accommodates a selection of connectors for each different type of speaker termination. (5) Bass can be tuned to the individual room and is better integrated and more tight, articulate, and palpable with the down-firing sub vs the rear-firing, split-tuned array. Etc. Everything has been thoroughly thought out.

The highs and lows are more extended. Deep organ notes are palpable (when appropriate). Resolution is better, but the sound is also smoother, more organic, and even a little more dynamic. The soundstage is deep and wide even though they are within 4" of the back wall. Off-axis imaging is great; maybe it is the way that Sean set them up on my 24' long wall, but the image does not change very much whether I am between the speakers, sitting in front of one of them, or standing against one of the side walls. And yet, everything that I liked about the Mk2s is still there. The sound easily fills my living room and the extended 45' long main living space of my house without a change in tone or sound quality when I am in a different room. I have listened for hours without any fatigue.
All I can say is that I was smitten with my Def 2's and went out to Rocky Mountain Audio Fest looking for a complimentary amp. After hearing the Def 4's, you will never be able to go back to the 2's. The only thing they share is the name, form factor, logo, and speaker spikes. Everything else has been dramatically improved. If you don't have the funds for the upgrade, DO NOT go listen to them because they will haunt you if you are a Zu lover.
I currently have the Def IIs. I requested and received information from Zu last week on the "Definition Mk III Transform". The work they do is extensive, much more than replacing the 10" drivers. The speaker is totally disassembled. They rematch tweeters, upgrade to a silver/oil Mundorf cap in the hi pass filter, upgrade to the latest hypex amps, all the electronics are replaced with a modular unit with new controls (sounds identical to what's in the Def IV). Additional bracing, damping and reinforcing is done to the cabinet. While I am sure there is a substantial difference between the Def II and Def IV, what I really want to know is the difference between the Def III and the Def IV. If the full Def III Transform gets me to 85% of the Def IV I believe I would be a pretty happy guy for a long time. I am hoping 213Cobra can provide that info.
213 is to busy listening to his 4 to write.
Is the rear firing bass array replaced with the downward firing sub?
I have had my Definition Mk4’s since Dec 20th and I use them with 5 other guys for doing blind testing of cables. We prefer a speaker with no crossover in the vocal range. The Nano driver is very fast and super revealing without be harsh in any way. The sub and sub amp are very well matched. After owning over 300 different speakers in my life I discovered Zu about 2 years ago. I have tested almost all Zu speakers and the Definition Mk4 is the best all around speaker I have owned in 30 years and also one of the least expensive speakers I have owned. If I didn’t like it would have already been up for sale. Make sure your cabling is up to the task and you will be in the recording studio with the artist; a true emotional experience.
As contented owner of Def2s, just a couple of things. Firstly, I've always loved the 'tone dense' sound of the Def2s, even though this is at the expense of best possible treble extension; so is the new Radian tweeter on the Def4s an improvement in this area?
Secondly, the massive bass output of the Def2s have led to room nodes issues, but I've been able to better integrate bass from the speakers into my room using the SpatialComputer Black Hole attenuator. Does the use of the single downward firing sub really improve upon the 4 rear firing drivers of the 2s?
Regards, Marc
I have also owned the Def 2 and truthfully they are an absolute steal for the money. They are not perfect but the things they do well they do very well. The Definition Mk4 is a different level and in my opinion competes very nice against any speaker in the $50K-$100k area. To answer both your questions; yes and yes. The Definition Mk4 is a different level and after owning much more expensive speakers I prefer the Definition Mk4. I will not go into the sound because that will be dependent on your equipment and cables but for me this is the best all around speaker I have heard.
Gsm18439 - the rear firing base array is not replaced as part of the Mk III upgrade. One other item of note is Zu said they would only be doing the Mk III upgrades until this fall.
Then the bass will be superior - tighter, deeper, more articulate.
I agree 100%. However, the Def III gets the new hypex amps and it looks like the same bass control package as the Def IV. I have to believe these will result in some improvements to the bass of Def II. I do not expect it to be as good as the Def IV. If 213cobra had the fully modified IIIs he will be able to provide the perspective I am looking for, if he chooses to post.
hi Musicxyz, that is quite a claim that the Def4s are the beating of $50k-$100k speakers-that puts them in Wilson Maxx/Focal Grand Utopia/Magico Q5 etc territory. I love my Def2s and am intrigued as to which speakers in this range play second fiddle.
Musicxyz, have you owned Merlin or Joseph Audio speakers? If so, how did they sound to you?
Please understand it is still just my opinion and there are a ton of variables that play into the scenario. I have owned both Merlin and Joseph and these are completely different than Zu because Zu does not use any crossover parts for 8 of the 10 octaves. My Wilson Grand slams and Magico were a complete different level than the Merlins or Joseph speakers but again the crossover in the more expensive speaker is an issue for me but perhaps other people can live with crossovers; I can’t. With 60’ of junk cooper in a coil and 5% tolerance levels on caps and resistors, how can any speaker designer claim their speaker is phase coherent at the listener’s ear? I believe the reason I prefer Zu is because they sound like the artist voice, phase coherent. There are some very good speakers on the market today but for me all the frequencies must arrive at my ear at the same time or the speaker becomes fatiguing. Again it is just one persons opinion. I could never go back to a speaker that has a crossover in the midrange area.
Musicxyz, us long-term Zu Def owners have always loved the authentic tone dense sound of the crossoverless FRDs in the design, but I am bowled over that you rate this improved design as superior to such uber speakers as the Wilson Grand Slam, esp. coming from your personal ownership. Looks like I really won't be able to resist the move upwards.
Upon getting bass integration sorted with the SpatialComputer Black Hole which the Def4s will improve upon further, can you comment upon specific improvements in treble extension/transparency going from the 2s to 4s, since this is the one area that could be reasonably criticised in the 2s.
You’re really comparing apples to oranges. It is tough to get to deep in detail because my system will be very different from your system but the Radian tweeter is much more transparent, detail and faster than the previous models. The Nano driver has about 30% more inner detail so ever cut is like listening to a new version of the old song. I have put on albums and had to check to make sure that it was the same album I thought I had put on. Wilson makes a great product but for me no matter what equipment I put on my Wilsons they still were lacking in emotion which tells me they are not phase coherent enough for me. The Mk4’s puts me in the recording studio with the artist but of course it takes great equipment and cables to complete the whole picture. All I can say is “if you are happy with your sound than stick with your equipment”. I am just giving my opinion it could be right or wrong for you.
Yes, Glory has it right. I've been too busy listening to my Def4s to take time to write about them. I bought about 50 more CDs and vinyl discs since they were delivered, and I'm plowing through my thousands of existing discs. It's cutting into my work productivity!

Here are the short strokes, while I get my full narrative together:

To understand Def 4 you have to know Def 1 and 2. I'll write about this later. The basics however are apparent regardless of your historical exposure to Zu.

1/ Top to bottom, Def 4 is for the first time a Definition-archtecture speaker that has the holistic charcter of Druid, with Definition's accuracy and scale. Its tone, speed and dynamic characteristics are now fully uniform top to bottom. In prior versions, the dual FRDs, super tweeter and the sub-bass array left traces of their independence. No more.

2/ Def4 soundstage is as wide and deep as your room allows, and will go beyond to serve the dimensional characteristics of the music performance recorded. For anything from a Blu-ray movie soundtrack to a full orchestra to a trio or solo performer in an intimate space, spatial representations are closer to the perception of live performance than in any Zu speaker to-date (though I haven't yet heard Dominance).

3/ Even in a tricky room, the new 12" cast-basket down-firing sub-bass driver and its driving amplifier more evenly loads a room with bass, with fewer resonance, bass-piling and reflective problems than the older and once-excellent 4x10" back-firing sub-bass line array on Def 1&2. Most of the bass resonance problems that I've in the past just had to listen through in my main room, are mitigated to the point of irrelevance. Bass is prodigious when the recording calls for it, but in all cases is reproduced with higher definition and charcter unique to the given bass instrument and the player's style, than in prior versions.

4/ Top to bottom transient uniformity is unprecedented for a dynamic speaker. Def4 has electrostatic-like speed and uniformity, while retaining the punchy heft of a responsive magnet-motor cone speaker.

5/ The inclusion of the Radian compression supertweeter is a very large advance over prior Definitions, if your high frequency hearing is still intact. It is extended, liquid-smooth, fast and not beamy. It is what Definition needed from Day 1. Similarly, the nano-treated main drivers are responsive and transparent to a new level of revelation because even further stiffness has been achieved in the cones, with only a fraction of the added mass of prior treatments. As I understand it, only around a gram or less of treatment compound is used now per driver. You hear it, in speed, attack, articulation and tone.

6/ As I'll elaborate in a more complete assessment, cabinet talk is suppressed yet again over the prior version, sharply reducing the tonal artifacts introduced by high SPLs in prior Definitions.

7/ An unexpected consequence of all this attention to advancement: somehow and counterintuitive to landing a more revealing speaker, regular Redbook CDs are more listenable and satisfying than ever before, without any change to my sources. I expected a more transparent transducer to render older, or more compressed or generally poor CDs to challenge my tolerance for listening to them. But the reverse is true. These speakers have me mining deeper into my CD collection than in quite awhile. Vinyl gets its due but I have a lot of music unavailable on vinyl, and I'm enjoying all of it more.

8/ Tonal integrity and holistic realism remain evident in the bursty, one-voice Zu way, but beyond what anyone has experienced who hasn't heard Dominance or Def4. This is not an incremental iteration of Defintion.

I''ll get more tapped into text tomorrow or Monday.

I agree 100% but couldn't you get into more detail; just kidding. The Mk4 is a total different level than the 2 or 3 and it should be at the price point they sell for. I will say that after owning a ton of speakers I don’t understand why this speaker doesn’t retail at $20K plus.
I have really dug my Def2s over the 5 years I've owned them, even more so with the SpatialComputer Black Hole sorting out bass integration issues in my room.
My main issue with them has always been the tweeter, which I feel has restricted the spkrs' microdynamic capabilities wrt to it's amazing macrodynamic prowess, leading to a dark tonal balance only lightened by bursts of treble when in the recorded material.
So, I'm so pleased that 213Cobra and Musicxyz have confirmed that treble extension is up there with the best, and not at the expense of the FRD magic macrodynamic picture, and opening up the microdynamic universe in music played.
Btw, to Musicxyz, do you think you're finally off your spkr merry-go-round and will stick with the Def4s? Can you resist the Dominances ( 3 FRD's, 2 supertweeters, 15" sub bass)?
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.

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?
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.

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.

Wow you get your $$$ worth reading 213 thoughts.
Agree with Glory, 213Cobra, you're a Godsend in setting down really detailed info that gets to the heart of the technical, and, more important, subjective experience of the Def4 experience over and above the Def2s.
Until this point I've really been happy to stay with my Def2s, but only since I've added the SpatialComputer Black Hole bass attenuator to sort out room nodes/standing waves, which has helped the 2s to integrate thru the low end I didn't think was possible. Sean Casey at Zu helped put me in this direction. I'd really recommend all Zu owners (and others) to investigate it, I believe Sean demoed it at Def4 launch at RMAF 2011, and I'm sure the 4s will benefit also.
My main push twds the 4s has been helped by comments that the Radian supertweeter really has helped the top end, that certainly lagged behind the FRD's in the 2s and always drew attention to itself.
So 213Cobra, you really feel the high end is more complete, and of a whole with the rest of the spkr?
Btw, which finishes have all you Def4 devotees ordered your spkrs in?
Much as I love the custom black finish, I feel this may be impractical wrt light reflections esp. while watching movies, and day to day maintenance. My decision will rest between true black matte and Cosmic Carbon.
My Definition 4s are painted in a high-gloss 2011/12 Cadillac color, Opulent Blue Metallic, with the exposed aluminum parts natural. My Druids are gloss Ferrari red. My first Definition 1.5s were gloss Maserati Blue Nettuno (this became a standard Zu color after I had the first pair built in that finish). My Def2s were high gloss Ferrari red. I use my speakers for 2 ch music and incorporate a 60" display, so for movies the systems are HT 2.0. I don't find the gloss finishes distracting for movie viewing, but then again I manage to ignore incandescent 845 tubes when watching movies so any reflections off the speakers' finish is barely noticeable by comparison. Day to day maintenance is only needed if you have a household of folks who can't keep their hands off the speakers. The gloss finishes are automotive paints that are taking much less punishment than is incurred by a car out in the weather and sun. A little Mequiar's or Mother's instant clean and shine, with a clean microfiber cloth makes quick work of it. But no question the matte finishes require even less attantion.

There are a couple of things to keep in mind about the upper frequencies integration on Def4. First, you're hearing the main full range drivers up to about 12kHz, compared to a two or three-way speaker where the tweeter is crossing in anywhere from 2.5kHz - 4kHz. So most of what you perceive as high frequency performance is determined by the FRD. The new nano drivers are lighter, stronger, faster and therefore more articulate, energetic and refined than the Def2 pre-HO drivers. The spesaker's horizontal spray is also wider than before and most of the Swiss cheese effects in the Def2 soundstage are filled in. That includes the top sparkle frequencies where the Radian plays. Compared to the Def2 FRD/supertweeter hand-off, which was very good at the time of introduction and nothing to be ashamed of today, the Def4 same interface is seamless spatially, tonally and in transient character, and instead of the FRD outpacing the supertweeter as in Def2, in this case if there's preference in sheer beauty at the hand-off, it's in favor of the Radian. This is a lovely tweeter used in supertweeter application here, far better than the ribbons that annoy me, and vastly more listenable than the various and horrid metal and diamond tweeters used in some of high-end's mega-brands. The Radian uses an aluminum dome but with a mylar surround, which avoids the peakiness of most metal dome tweeters. It's not just a claim -- you can hear its extended and smooth neutrality, with dispersion more closely matched to the new FRD than in Def2.

Sidebar: 35 years ago, the Advent Loudspeaker was a great basis for building a highly credible high end system, in a market with much less choice, especially if you had the space for the Double Advent system Absolute Sound helped to popularize. That speaker produced very little worth hearing above 13kHz in a simple 2-way configuration, and spec'd out to perhaps 18kHz. At that time, Jon Dahlquist included a piezo supertweeter on his DQ10, which was flat out to 25kHz, but it beamed like a lighthouse. People did all sorts of things to improve it: wool diffusers over the piezo; replace it with a ribbon tweeter; remove it. Some people just said "....I'll keep my Advents" because they had a rightness to them without the distraction of DQ10's beaming supertweeter.

Well, listen to a Def4, or a Def2 for that matter and have two people handy to put their palms over the supertweeters while you play music. You're hearing nearly the top end of an Advent loudspeaker from the FRD's upper limit. Most of the character of the top end is determined by what you're hearing there. What any Definition's supertweeter adds is harmonic completion, further spatial cues and the subtleties of dfferentiation in expression via instrument materials, playing techniques, vocal inflection and tone. None of the Definitions added this with any ice-pick elements. The cabinet on Def1.5 was a bigger contributor to glare at high volumes than was the supertweeter. In Def2, the top end smoothed out some, but if you needed proof how much more influential the FRD is, you only had to upgrade your Def2s to the 2010 HO drivers. That put the supertweeter's relative contribution in perspective. In Def4 the Radian is a mister instead of a hose with a nozzle. But it's the new nano FRD that sets the stage for you to appreciate the Radian's deftness, dexterity and refinement.

I love my piano black. Actually, I rather like the light reflections in the daytime and don't use them for video. Maintenance has not been a problem.