Zu Defintion 1.5 vs Def IV

very quick electrical surges due to hurricane Sandy blew one of my sub amps. Now, I'm reconsidering the IVs or having Zu replace the blown amp. Is the upgrade to the IVs worth the $$? Any Zu owner that can site specific differences, kudos, etc? Bass as prodigious as earler Defs? The whole nine if you could. If it be easier a call would be very cool. 516-316-3311...Phil, you were responsible for my Def 1.5 purchase. Please give me another shout. thanks in advance.
The Def 3 (for roughly 1/2 the cost) is not a bad option either. If Zu is still selling them.
Houston we have lift off!
Def 4s it is. I'd still love to hear about what I'm going to hear...
Mark could you compare the Def 3 to the Def 4? You might be one of the few who can shed light on the two. I have the 3's and love them.

And how is your new amp working out? What did you decide on after the PX-25?
I recently shepherded a friend here in Los Angeles into Definition 3s, his first Zu speaker. He is driving them with a Cary SLI-80 KT88 integrated amplifier running in pseudo-triode mode, with both CD and vinyl sources. He migrated to Zu from Triangle, after a series of unsatisfying trials with crossover-based speakers. I've been able to spend about 30 hours listening to Def 3s, considering the differences between them and my Def4s, while helping him dial in his system. A few concrete observations:

1/ The nano-FRD, as sonic anchor to both Def3 & 4, gives both speakers the same essential character. In either speaker, you get the speed, agility, openness, elevated articulation and tone density that the nano driver delivers over the prior lively Zu FRD iterations. The tonal darkness of Def2 prior to the 2010 HO drivers, over Def1.5, is gone. The Def1.5's burstier jump factor is back, without the MDF glare and other cabinet talk at high volumes.

2/ While Def3 is built in Def2 and Def1.5 cabinets that are reworked with more internal bracing and other resonance damping, the Def4 cabinet is still a different structure and it is "quieter" at high volumes. You'll not notice obvious cabinet talk from Def3 in isolation but hearing both in close succession, Def4 has the "blacker" background with nominally less cabinet presence when pushed.

3/ Def2 had only a level control for adjusting the sub-bass array's output, so Def3 having the full Def4 sub amplification and control panel puts the differences between the older rear-firing 4x10" line sub array and the newer 12" downfiring single driver, in sharper relief. Until Def4, Def1.5/Def2 deep bass sounded impressive, convincing and well matched to the fast dynamics of the FRD. In Def3, that's still true, with the added benefit of now having much more precise control over the deep bass output characteristics for mitigating acoustic problems in the room. But it's when you hear Def4's 12" downfiring sub that you appreciate by comparison its improved clarity of deep bass information for being consistent with the instrument making the sound, and the precision of single-driver unity over 4 drivers. The stun factor of punch from the 12" is also vividly greater. The Def4 further distances itself from Def3 by the superior evenness with which the downfiring sub loads the room with deep bass SPL. If Def3 and Def4 cost the same, you'd obviously want Def4. But they don't. Considering the cost saving of Def3, its sub bass array delivers better deep bass presence and defintion than anything else coming from a speaker of its footprint and cost, and it's better than Def2 or 1.5. So which one you want is simply a matter of what you can or want to pay.

4/ As with the differences in sub bass output, so it goes with the difference of supertweeters. Judged in isolation, Def3 using the prior Zu supertweeter, has a sparkling top end for harmonic completeness, that is well matched to the nano-FRD's whizzer output. The older supertweeter smoothly takes the hand-off for extension beyond 12kHz. But it is by comparison a ruffian against the exceedingly graceful Radian 850 compression tweeter. Your specific sonic priorities will affect whether you hear the downfiring 12" sub or the Radian 850 supertweeter as the greater benefit to Def4 over Def3, but to me it's the Radian that makes the Def4 in today's market a $35,000 speaker. That's not to say that Def3 doesn't deliver more comparative sonic worth than its price -- it does, like all Zu speakers. But the older Zu tweeter holds Def3 back from confidently disrupting the middle five-figures speaker market. The grace and effortless harmonic wash of the Radian 850 makes it probably the most beautiful yet truthful tweeter I can remember hearing.

If you own Def3 and want to keep your fiscal discipline, then only hear Def4 in someone else's system where you can write off the lovely top end and the exceptionally articulate bottom as resulting from other components in their system. If you are deciding whether to buy Def3 on value principles or extend yourself for Def4, these are the actionable differences. Decide what they are worth to you. If you have Def1.5 or Def2, either newer speaker will be an emotionally satisfying upgrade to your enjoyment of music playback. If you are migrating from another brand's crossover-intensive speaker, then any Zu will prove illuminating.

Beautifully written, as usual....I can do the $$ so it's a no brainer. The Radian 850 tweeter sounds very exciting.
First off, I don't think I had the Def 3's here long enough for a good
comparison evaluation. Sounds like Phil actually has more hours logged on
the Def 3 than I had in the short period they were here. And, I certainly can’t
touch his expertise in describing the two.
In any event, my initial complaint to Sean with the 3's was a somewhat
bright top end-mostly with CD's. I had no complaints playing vinyl though.
Sean had me try rolling tubes and toeing out the speakers. Rolling tubes
didn't do much for the brightness, but toeing out helped a bit. In all fairness, I
have a lot of ceiling (drywall) here, and nothing can be done about it. As for
WAF that is.
The Radian 850 tweeter was a big improvement over the 3’s for my ears.
None of that harshness I had with the 3’s. And I can report that I am listening
to more digital than ever since my re entry into vinyl a few years ago. I will say
though that my 4’s are toed out just enough so they cross somewhere just
behind my listening spot to sound best to me.
As for my amp change, I was finding that at times I was maximizing the
volume of the PX25. 6 watts of SET power should be fine for most, but I do
like to rock sometimes and my room is on the large side. I wanted more
reserve power on hand so I picked up an 845 based Art Audio Carissa at 16
watts per channel. Sean mentioned to me that for my musical tastes and room
size that 10 watts should be minimum. I have plenty of reserve power on
hand with the Carissa.
I still say that I think the Def 3 is a bargain of a lifetime! You get a lot of
the Def 4 for about 1/2 the cost.
Thanks Mark. No Radian on the Def3s is the deal breaker for me. The high end was always a bit of a problem for me with my Def1.5s and listening to all the Zu people who have heard both, including you, makes this a no brainer. Now all I have to do is pack and ship my 1.5s (ouch) and wait. My SET is good for 32wpc clean. Ear bleed levels for me. Speaking of ear bleed levels, year ago I had a friend bring over his Bryston 4B to hook up to my rig to hear what these babies could do. Never got close to red lining the Bryston. My pictures were moving. Devastating, ear shattering, killer sound. My Bel Canto does it when I need the hair on the back of my neck to stand. Most of my listening is oh so sweet.
I often wonder how long it takes in this expensive hobby for people to become tired of the search for 'their' system. I know that I have spent, and lost, a bunch of money in the 3 years since I truly have explored high end audio. Thankfully I ran, and researched, my way into wonderful products. My delight was pretty much satisfied by my Zu Essence.

I have agree that when you have not heard Zu, any Zu will do. That is my experience exactly.
My experience what works now is a time and fate thing. If my Def 1.5 amp had not blown, audio life would go on 'til something else happened with my rig. My laser is going south on my Exemplar, hence, a new laser or a different more costly John Tucker mod? It's crazy, but I have had this rig for 5 years and have been very satisfied. The thought of going from the 1.5 to the 4 is very exciting. With the trade in it is $$ friendly to the wife. Happy Holidays
Late Channakah gift: Ordered my Def4s today. Zu (love those guys) will give me lead time to send back my Ibis speaker cable to reterminate. When they arrive I plunk my Def 1.5s in the box and back to Zu for my credit. Fedex or UPS? I'm leaning Fedex from experience (from The Hamptons NY), but never shipped anything this big. Suggestions?
I just shipped a $4K Audio Research amp from Ohio to Albany, NY using FedEx. It was delivered during the busiest week of the year Dec 20, 2012. Perfect with no complaints.

I have used them for amps, speakers, stands, and turntable without fail. I always take pictures and buy insurance.

Good Luck and congratulations!!!!
I agree with the FedEx choice Warren. Also the nice custom boxes that Zu sends the Def 4's in are bullet proof for the most part so you should be safe. What color are your 1.5's btw? Maybe someone wants a jump on what will be the next Def 3......
Who to use for shipping is a crap shoot. Freight, strapped to a pallet, would be best if you could swing the $$$. I believe that's how Zu is going to ship your Def 4's. I would make sure to take plenty of photos during packing them up showing them in the custom foam enclosure. FWIW, I sent my Def 3's back to Zu with UPS ground without issues.
By the way, what color did you order your 4's?
My 1.5s are red matte. Not Ferrari red, rather Mercedes "Mars" red. My 4s are natural maple. Light and beachy like our home. My (5years ago) 1.5s came on a pallet because Zus packaging was the pits. I could never send my 1.5s back in them unless they were strapped to a pallet. That's why (doing it backwards, but less expensive) I'll send my 1.5s back in the same box of my 4s. Sean says they will fit like a glove and not to worry. Christian says I should be seeing these babies around mid February...sweet
I sent my Def 1.9s and my original pair of Def 2s to Zu using FEDEX ground without a problem. That is what Zu recommended and what Zu used to send me all but my Def 4s.
Fedex it be. Gsm your system appears to be in a crib (very live listening area) similar to mine, in that I too have very high (12’) ceilings and my speakers will be resting on the floor with an area rug inches away. I’m imagining the down firing woofer. Must be nice.
My room is 24 x 14.5 x 16 high. The Def 4s are on the long wall and within a couple of inches of the back wall. However, the room is one end of an open plan that is about 45' long, albeit broken up by fireplace, kitchen, mezzanine study above the kitchen, etc. There are no rugs on the floor. I was lucky in that Sean delivered them during one of his East Coast trips and dialed them. Bass is very deep, very tight. The SPL vs frequency curves on the Def 4 spec sheet are from my room.
That is quite a space you got there. What AD issue was your crib in? I'd like to check it out. I've been AD for 20 years. Also, when you're in the sweet seat, (I don't know what your listening pleasure is, but since you're a tube guy?) how does jazz,classical etc. sound?
It was first published in the Feb 1996 issue of AD. I listen to classical (from Renaissance polyphony to modern symphonies, chamber and large scale works for chorus and orchestra, just not much opera), jazz, female vocals, classical and alternative rock, etc. Basically everything. Good recordings sound good. Bad recordings get trashed. I use tubes with the Def 4s because they sound great together (especially the Takatsuki 300b), but SS with the Celestion SL-700s in my bedroom.
So, as I read you, when you you're in the sweet spot,your rig delivers intimate, revealing and sweet sound in that huge volume of air you got there? I'm thinking jazz plus Ella, Sarah, Anita and the like?
Yes. But off axis listening is also good, much better than previous Defs.
veddy good. I can't wait. Knowing Zu this may be a very long while. What did F Scott Peck say?--"delay your gratification....