Zu Definition owners who stepped up to the Def 4

Would like to hear from past owners of the earlier Definitions, who stepped up to the Def 4;

Wondering how the 4-10" subs of the earlier Def's stack up against the 1-12" in the Def 4. Do you feel the Def 4 is putting out less bass because of the one woofer?

In the Def 4, I notice the built in amp sits directly over the the sub woofer. Any repercussions because of this layout?

I know there is a thread currently running about comparisons of these speakers, but I really don't want to read through some 440+ posts.

Thanks in advance for your comments.
ask your question on the Zu Def4 thread. you aren't special :)
The posts by Phil (213Cobra) are the most informative.
The 12" downfiring sub in Def4 is cleaner, quicker, and it loads the room more evenly. It is in all ways better than the 4x10" linear sub array on earlier Definitions. Plus the internal amp is better, cleaner, more powerful -- and you have far more control over deep bass/room interations with the parametric, phase and hinge frequency variables. The rest is in the Zu Definition 3 thread here.

Hi Mark,
What I remember reading is that the new woofers benefit from firing downward and are braced considerably better in the 4's. I have the 3's and Sean and other owners have told me that the 4 is better in two regards:
1. The new Radian tweeter
2. Improved bass due to the above reasons.

I have an invitation to hear a pair locally and if I do make it I will let you know my thoughts.

Thanks for pointing me in the right direction. I see Phil is a wealth of information
on this subject. I have a better insight as to the quantity and quality of the bass

Please report back if/when you hear the Def 4's, I'd love to hear you're findings,
thoughts and comments.

Thanks for clearing that up. I guess I'm from the old school thinking that more is
better, so 4-10" must be better than 1-12" right? I read about the
issues the old design has, so it all makes sense to me now.

All other things being equal, more cone area to move air is "better." But all other things aren't equal in this case. Four drivers don't deliver the same absolute dynamic unity as one. The 12" in the Def4 is a substantial cast-basket driver with a more powerful motor and it is bolted horizontally to the massive machined aluminum plinth rather than screwed on the vertical plane to wood. And even if that weren't enough difference, Def4 adds an array of five controls for the sub, against just a level control in Def2. The one area of theoretical compromise is that the sub's internal amp is proximate to the 12" driver. If you really worried about that the amplification could be externalized, but then the elegant unitary integration of all Def4 elements into one simple box would be ruined. Anyone so inclined can always save their money for Dominance if they hanker for more boxes and cable on the floor!

One bit of advice I can volunteer for those who can't easily upgrade to the 4s, love the 2s, but have some issues with bass integration, is to install a SpatialComputer Bass Anti Wave Generator. In my room it has made great strides in evening out certain standing waves and bass nodes. So much so that previous dissatisfaction with bass-room integration have been largely solved.
From what I gather the 4s have really solved these issues further with the single sub-bass driver, all the way into the high treble.
When my 4s are installed in the next 2-4 weeks, I'll report my findings.
Phil, is there any reason Zu haven't fitted an internal amp for the 15" sub driver in the Dominance? I would love to be able to afford this model one day, but need for more expenditure on bi amping the speaker takes it further out of range.
There's certainly room for an internal amp in Dominance. In designing a SotA speaker, Zu just took the absolutist route to require external amplification & control for the 15". As a Zu customer I've expressed my preference for a version of Dominance with the Def-like integrated amp/control module internally mounted. It remains to be seen whether the market gets it. I'm sure it's not Sean's highest priority nor should it be.


"The one area of theoretical compromise is that the sub's internal amp is
proximate to the 12" driver"

I just had a talk with Sean about this. I was reassured that the amp being
close is not a problem with the woofer doing its job. And that more of a
concern was the woofer vibration to the amp. He mention that is why they
use extra measures to keep the amp assembled strongly as so not to let the
vibrations of the woofer rattle anything in the amp.

" If you really worried about that the amplification could be
externalized, but then the elegant unitary integration of all Def4 elements into
one simple box would be ruined"

Yes, very true. We also talked about this too. Sean mentioned to me that they
are coming out with a kit that will allow one to remove the amp from the Def
4 (and I'm thinking possibly the prior defs as well?) and incorporate their own
amp to drive the sub. There will be a plate that will fit over the amp opening
to cover the hole and you will receive a credit for returning the amp. This kit
will be posted on their website soon. What a great idea for those who want to
go that route.
I am with Phil on this. The integrated solution is so elegant and in only a 12"x12" foot print. Plus, some of the hassles with accessing and servicing the built-in amplifier in the Def 2s have been solved with the design of the Def 4s. As I understand it, Zu did consider eliminating the built-in amplifier in the Def 4's design; I am glad that they did not.
I don't think that I would consider opting out of the built in amp either now that I have a better understanding of the pros and cons.
However, I think Sean scored big here giving the end user the option. As I understand it, some like the idea of having all their electronics together, on one rack. I have to admit, I sometimes find myself running over to the speakers to adjust the volume when switching to different kinds of music. Not a problem with me (after all, anyone who plays vinyl is always jumping up anyway), but for some I'm sure.
When I mentioned the compromise of an internal amp, I was referring to the known degradation of the sound of especially solid state circuits subjected to vibration. But the deleterious effects are mostly noticed in upper midrange and high freuqnecies, if they are noticed at all. I don't consider it a significant issue in the Zu sub imprementation. Offering a kit permitting removal of the internal amp and controls in exchange for easy connection of external sub amplification and a croosover or active low pass filter is essentially a way to revive the concept of the Definition 1.5-era Definition Pro, which had few takers. But in this case it can be done without having to ship a separate model.

At the time of the Def Pro, Definition 1.5 had only recently gotten a sub level control. (My original Def 1.5s in 2005 were delivered with no sub adjustment of any kind. My first feedback to Sean and Adam was to ask for a level control and suggested that all Definitions should be so built. Sean and Adam soon showed up at my house in Los Angeles to do a field upgrade and then they proceeded to visit every Definitions owner in the US to install level controls.)

So Def Pro was introduced in the context of Definitions only having simple level controls on the sub array. I think with the five-way sub control panel on Def 4 along with the big driver upgrade, downfiring, and the amp improvement inside, the difference externalizing the sub electronics will be so much smaller that it will be worth tangling up your room with more gear and cable in only the most demanding and extraordinary circumstances, like if you are trying to load a very large space and plan to use high power monoblocks on the main drivers/supertweet and need something mammoth for the sub. And if you were going to that trouble, a pair of Zu's new subs used in conjunction with the internal Def4 sub would be cleaner and likely more effective.

But it's the Zu way to accommodate downstream customization so takers there may be. Still, one of the chief appeals and value propositions of the Definition format is having everything for 16Hz - 25kHz objective presentation in a single simple column for regular 2.0 gear.

A newbie here with a question for Zu def 4 owners. I'm going the set, high efficiency route, I get it. Would someone comment on comb filtering and the D-appolito arrangement in the Zu loudspeakers if its even an issue to discuss? Thank you
It's not strictly D'App spacing. Regardless, combing in Defs is incidental and isn't worth worrying about.