Zu Soul Superfly

I just ordered a pair of the new Zu speakers on a whim. I was going to wait for information, but the fact that they threw in the free superfly upgrades to the first 30 people got me.

From a similar thread it sounds like some of you guys have heard the speaker despite information only being released today. I'm wondering what you can share about it?

Also, I am really hoping it works with a Firstwatt F1 amplifier. Can anyone comment as to that? I know the Druid's and Essences worked OK.
Firstwatt should work great with them. You might also confirm with Zu.
The Zu website has a list of amps they tried the Soul with. The recommended a Dynaco st 70 unmodified I believ, for best bang for buck amp. Check the site, I may be wrong.
Thanks! This is reassuring.

The gentleman I spoke to at Zu said Nelson's gear is great and that it should all sound good with it, but that he was unfamiliar/did not test it with the firstwatt amps. I just know as current amplifiers they really aren't suitable for cross over speakers, so I was wondering if anyone had any specific info.
How could it not work based upon the spec's?
A friend of mine received s/n 0001/0002 last week. I had a chance to listen to his speakers, which are Soul Superfly, extensively, with a few different amplifiers. The FirstWatt will be fine. That is to say, if you like the FirstWatt F1, you'll like it on Soul. If you don't like the F1, Soul won't make you like it, except for one thing: This is a nominal 16 ohm impedance speaker. Most solid state amps will output less power into this load but also sound smoother.

You can assume any amp that works well with Druid will work well with this. Soul has deeper bass response, and it is more projecting and more vivid than Druid Mk 4-08, but it is the essential Zu holistic tone presentation. Using the some further refinements to the FRD learned from development of the Essence, this speaker has the widest midrange dispersion of any of the Zu single FRD speakers. It also has the best implementation so far of the Griewe cabinet, and now the floor-to-cabinet gap is non-critical, without the complication of the Essence double plinth.

Think super Druid 4-08 in a more compact form, rather than Essence. Forgoing the ribbon tweeter allows Zu to run the FRD at normal Zu efficiency, and the dynamic supertweeter contributes the meatier more musical harmonic information that the ribbon thins. Soul Superfly is a vivid, punchy, neutral and tone-rich speaker that resets your assumptions about how much cash to allocate to power amplification, yet its impedance and efficiency allow some vanishingly cheap amplifiers to make music instead of noise.

My friend has built new a $10K system around a pair of Superfly Soul, and results easily demonstrate it was exactly the right thing to do.

Will the Soul Superfly work in a larger room (18 x 30 x 10) as the Essence does?
Yes. When I listened to them in my room they sounded fine. The room is 16' x 24' x 10' (Sloping cathedrial cieling)
How does te porting system work on this model? Is it the same system as the Essence or is it some thing new.
Its a "twisted" version of the Griewe (sp?) loading. On the Soul page on their site, it has a drawing of it. Pretty cool how they come up with these ideas. I mean who would have thought to twist it? Maybe an iPad told them it would sound better? :)
On another note, I wonder how a Sonos ZP120 would sound on the Soul.....hmmmm.....talk about a minimalist system. :)
Been looking at the superfly. The sales ending today. It's decisions like this that define a man......and apparently I'm a wimp.
Are you a wimp in that you wussed out, or in that you caved in?

I guess the sale really is over which in a way is a relief in that even if they aren't for me, I can likely re-coupe what I paid locally rather than incurring a shipping expense.

I'm very excited.
Totally wimp out. As a married guy with 3 pairs of spks already, no matter how high the WAF the Zu is, I wouldn't be able to convince my wife that 1.8k for a 101db spk is a great investment in this short amount of time. Get it first, ask question later could work(its not like a 25k avantgarde), but there are no reviews yet, so I dunno even know if I can really live with the sound.

I have high eff. w/ 300b amp, but still based on users' comments, I feel like the Zu sound is not for everyone.
In a year you should be able to pick them up for $1300. Maybe a little more $$ for the Superfly, which I read makes them sound like they should.

Resale??? All the emails--Are these the Superfly version??? If not I'll give you $900...
I would think the resale would be no worse than other brands. It should be better because there is only one "dealer" so prices are fixed.

I judge resale on how much I lose. Look at Wilsons, they sell for as low as 53% of there retail just 4 years after they came out. Now when you are taking 27+ grand you lose a lot of cash. Now losing 47% of $1800 seems like spare change in comparison...

I would buy one of the super fly just to try out even though my gut tells me they are not for me.

You caught my attention with your excellent description of the smallish but potentially significant differences between Druid and Essence which articulated my views on them better than I ever could. I would be happy to buy Essence but my inclination has always been toward Druid. I have always been especially taken by the presence of the Druid. The sense that a horn player is in the room and standing thus high and really moving air at you.

Bearing that in mind the Soul seems on paper to be right up my street. I need to hear a pair, likely to be mid June in the UK, but at the price I'm almost tempted to just plunge in there. My reservations are that, whilst the loss of a foot of height plays well with Mrs. H, how does the speaker perform in terms of image height especially as the frd is now below the tweeter? Does it still give that great sense of presence, which was the loss in the Essence for me? Does it still have the lovely mud band if the Druid?

Essentially I guess I'm asking if it really is Druid plus or is it just a variation on Essence or Presence?


Zu says the Soul surpasses the Druid in every way. Sean and Adam would not make such a bold statement if it were not true. Looks like the reviewers are already forming a line. I wish I would have been in a position to get in on the sale. Oh well. In due time, I think a pair of Superfly will be in my living room. Ferrari Red? Let us hope so! ;)
I am just curious why did they already abandon the Ribbon Tweet from the essence after one new speaker with it and go back?
@ Undertow. Cost, the soul costs significantly less than the Essence. Those ribbon tweeters are expensive.

PS. I dove for the $1800 Superfly. More money than I had to spend on speakers. I hope they are at least as good in every way as the Druid IV/08. That would make them worth it in my eyes.
>Zu says the Soul surpasses the Druid in every way<

So where does that leave the Essence? A red headed step child? Not everyone seems to agree that the Essence is even better than the Druid. Now we have a 1800.00 speaker that's possibly better than both?

The ribbon tweeter is gone because of efficiency. I tried the original Druids, they didn't work for me, though I heard a lot of promise. The Essence being less efficient didn't have enough spls with my 300b amps.
I suspect that Zu has really put it together on the Soul and decided to buy in. Hopefully it is the answer to a lot of our desire for a decent looking small footprint, mostly full range speaker.
I applaud Zu for making what seems to be a "statement" speaker that is affordable and fun. There is way too much gravitas (am I actually thinking a different word?)in high end speakers.
Because of a recent house renovation, I was going to treat myself to a great pair of speakers. I have spent the last few months scouring NYC for something special, and while there are plenty of good, even great speakers, the bullshit (I guess I was) and ludicrous cost for what in the most part are outsourced components in nicely finished but generally ugly boxes, makes you want to just bury your ears in a good set of phones.
So- Zu I hope you have succeeded in bringing some life to the party. And, I hope that party gets to my house in the next couple of weeks. Supa-fly!
>> Phil, You caught my attention with your excellent description of the smallish but potentially significant differences between Druid and Essence which articulated my views on them better than I ever could. I would be happy to buy Essence but my inclination has always been toward Druid. I have always been especially taken by the presence of the Druid. The sense that a horn player is in the room and standing thus high and really moving air at you.<<

Yes, this is a specific advantage of Druid. Even the higher-resolution Definition 2, has to give up a bit of unity and coherence to the single-FRD Druid, on music that doesn't present significant scalar challenges. I have two systems with similar-grade components, but one has Druid 4-08 and the other Definition 2. I don't automatically choose to listen to Defs for everything. I default to Druids for some things, and for those choices really nothing else will quite do. Essence gained scale by virtue of its wider dispersion from the revised FRD and deeper bass along with the extended "hifi" top end. But it lost some of the magical presence of Druid when some efficiency had to be dialed back. I liken the difference as being similar to the sonic delta between same-quality SET and push-pull tube amps. The p-p amps might seem more impressive at first, but you soon notice a permanent reduction of focus.

>>but at the price I'm almost tempted to just plunge in there<<

I think anyone who likes Druids can just plunge in without risk.

>>My reservations are that, whilst the loss of a foot of height plays well with Mrs. H, how does the speaker perform in terms of image height especially as the frd is now below the tweeter?<<

I've always thought the Druid's image presentation is a bit on the high side with respect to its vertical center. Kind of like sitting 1st row in a club with the performer on a short-rise platform stage higher than you. With Soul, the FRD is on an angled baffle, pointing slightly up. It images well in terms of vertical centerpoint from a normal home seating position. The sound image vertical centerpoint is higher than the FRD. There is no problem introduced by having the supertweeter on top. For the footprint to be on target in a truncated pyramid column shape, the FRD had to be placed lower, but as high as possible on the baffle.

>>Does it still give that great sense of presence, which was the loss in the Essence for me?<<

If you get the Superfly Edition, it gives more. Now, even with Zu's factory abuse break-in, you'll still need some play-in to get them to a state of ultimate tone, but out of the box they have all of the Druid 4-08's presence and tone-density, plus.

>>Does it still have the lovely mid band 0f the Druid?<<

Yes, with less cabinet noise at high volume.

>>Essentially I guess I'm asking if it really is Druid plus or is it just a variation on Essence or Presence?<<

The only thing Soul Superfly really inherits from Essence is the wider horizontal dispersion made possible by the remodeled whizzer and cylindrical phase plug. Otherwise, the motor and cone mass are tuned for Soul, and the efficiency is restored. The ribbon-instigated compromises are absent because the ribbon is thankfully *not* possible at this speaker's pricing. And it achieves Essence level of Griewe model performance on the low end in a smaller cabinet than Essence. Zu started out intending to build a market-expanding "recession speaker" and ended up finding a way to slash price yet build a "Super Druid" in a smaller column.

Regular Soul will be good but Superfly is the ticket for this crowd, well worth the delta in price, post intro sale.

>>I am just curious why did they already abandon the Ribbon Tweet from the essence after one new speaker with it and go back?<<

They didn't abandon the ribbon. You can still order Essence, and when that speaker is revised it will have a ribbon tweet again, but perhaps a different one. No credible ribbon supertweeter could be accommodated in the economics of the Soul speaker. Below Essence, I'm sure you'll continue to see dome-behind-lens, Druid-style.

I'm glad I don't own the Zu commodity. Things are not looking good resale wise for the Essence or Druid owner. Glad I lost the $600 on the Essence while I could.

The Soul gal on the website looks like an angry perfume model. Can the five preferred reviewers "Pump up the jam?" Hope so!
Shakey - I do not see (hear) it as a matter of "better than", but just different. I really like the sound of the Defs and Essence, though never liked the Druids. Heard the Soul and don't like that either. No surprise since its sound seems to me to be in line with the Druid. IMO, soundwise, the Druid/Soul do not compete at all with the Def/Essence because of such different sound. So if I lived in Zutown, I'd see no reason to bannish the Essence to red headed stepchild status. Just my two pesos.

Thank you kindly for the response. Between the stuff on here and email responses from Sean Casey I think we're looking at a sale in due course. Looks like I got sale price too.

You can't imagine how annoyed I was when Druid discontinued. I could have gone for Presence but the grill was a deal breaker in our lounge. I like the Essence but mourned the loss of presence. I'll not be able to afford the Essence barring a miracle so Zu have rather made my month.

And of course I missed out the obvious question. Do you plan to replace your Druids?


My Druids are Frankendruids, in some respects. I bought them used over five years ago, so they are one of the earlier cabinets in gloss red. First generation; and they had been upgraded to "Mk 2.5" status then. But they have the early B3 wiring and connector so with a pair of Ibis B3 cables I have Zu B3 cable geometry from the FRD all the way back to the amp outputs. This makes a clear difference. These speakers were upgraded to 4-08, with a further upgraded cap on the supertweeter, and the internal wiring is Ibis. So they sound better than standard Mk 4-08.

Even so, my friend who bought the first pair of production Soul Superfly has speakers that are now a bit better than my Druids, and they aren't even thoroughly broken in yet. You could order Druids to the same standard and get same sound except for the last stretch of bass extension, but the only reason to do so is if you prefer the Druid form factor as a visual statement. Druid costs more to make and is fussier to set up. Soul Superfly addresses the remaining anomalies of Druid by moving past the limits imposed by the now 10-years-old cabinet design. That iconic cabinet was not designed with the benefits of an eventual full Griewe model incorporation in mind. So you get sonic progress at a lower price, which can't be bad.

>>Do you plan to replace your Druids?<<

Yes. Although I may keep them for another use, for sentimental reasons.

For those of you who have heard the new Zus and the Cain and Cain Abbys, I'm wondering--how do the Superflys fare in terms of overall coherence.

While I can definitely pick and chose things I'd love to add to the performance I currently have, I certainly don't want to give this aspect up.
I auditioned Abbys (with and without the supertweeter) before I bought Druids back in 2005, and have heard them occasionally since. In fact, at the time it was my intent to buy Abbys for one of my systems, until I got in front of a pair of Druids. There's certainly no less coherence from the Zu FRD, and the latest updates to the Zu FRD as implemented in Soul only further improve its performance in this respect. The Fostex driver options in the Abby do not meet or exceed the Zu FRD performance in any way, though the Abby is a very good speaker, with remarkable tonal and transient coherence. However, its intrinsic single-driver coherence, where it is closest to being competitive with Zu, does not overcome comparative lack of drive, range, dynamic aliveness, and combination of power handling with high efficiency. I considered Zu Druids prior to the 4-08 upgrade clearly superior to Abbys, and the 4-08 upgrade to Druids rocketed their lead, then the further advance of Soul Superfly over Druids puts quite a lot of distance between Soul and Abby.

Thanks for sharing your findings, Phil. I'm not a person that holds onto gear that doesn't do it for me, and I've had my Abbys for more than five years now... I'm very excited and anxious to see for myself what these Superflys are all about.

Have they begun shipping yet or is it just a few of their local friends who were lucky enough to get their hands on them prior to June.
Gopher - A friend of mine got the first pair of Soul Superfly on an advance special order for a custom finish. Zu's first regular production Superfly speakers should begin shipping in the next week or ten days, so perhaps there will be some Audiogoners among the recipients.

Phil, I have Druids mk4/08 with further upgraded tweeter network Mundorf silver oil cap etc same as zu Def2 and superfly. I also have 2 x mini methods.

In your opinion what improvements would I notice if I swapped with the superfly.

I love the Druids presentation, as close to live a I've had. The 2 mini methods add a huge amount of bass....... I can only imagine what the Def2 sound like in this department. I feel Druids excel in guitar and voice driven music, but they also sound great with electronic dance stuff.

So I guess I'm asking about the FRD and how much better is it in the superfy?

If you have Druid 4-08 with Mundorf silver oil in the network, you're quite close to Soul Superfly, and of course stereo Mini-Methods will outperform Superfly on bass - albeit at expense of space and complication.

The FRD in Soul has wider horizontal dispersion and more vivid, punchier dynamic behavior than what you get from Druid 4-08. It's a refinement of the Zu FRD, so essential character isn't changed. But it's clearly an evolution that makes the FRD better, and not in any way worse. The tone density is similar between the two, but the newer FRD is burstier and sounds faster on transient attack. The motor is stronger, the cone a little lighter than older versions, and the phase plug is not only cylindrical but the detail on the face of the cylinder is essential to its role. The last trace of darkness in the Druid's sound -- much removed by the 4-08 upgrade -- is now gone. In many rooms, given the trouble most rooms pose in the deep bass region, Soul's 30Hz lower flat limit will be both easier to manage and more truthful than the deeper subs, but if you have that sorted, OK. But sans subs, bass from the Soul is in all ways better than what's possible from the Druid form factor.

I plan on replacing my Druids with Superfly Soul, though I don't use subwoofers. The price is right and the improvement is of sufficient increment to be worthwhile to me, for the system I use Druids in. But it is an evolutionary upgrade from your speakers, not a dramatic one.

Thanks, given the expense of shipping speaker to Australia it's probably not worth it.... However I may see if Zu would swap the FRD only in the future.....

I've also been thinking about remaking the Druid cabinet using some bitumen laminated noise gaurd ply we use in other applications, very dense and resonant free in comparison to mdf.

You make a compelling case for the Soul Superfly. May I ask how many hours listening time you had with them when you formed your judgement?

I don't need much time to judge a new speaker, or anything else for that matter. But I've had several hours with Soul on 845 monoblocks, and more coming up. Nothing I heard in the so-far last hour contradicted anything I heard in the first ten minutes, and vice-versa. My experience with various Zu speakers so far suggest that a pair of Soul Superfly will continue to improve for the next 18 months, and in no way get worse as they break in.

I agree with Phil regarding break-in time for Zu speakers. The improvement over time was not subtle, and in my experience came in "jumps." Most of posts compared Superfly vs Druid; I am curious about the differences between Superfly and Definition speakers.
>>I am curious about the differences between Superfly and Definition speakers.<<

Having both Definition 2.0 and Druid 4-08 in two different systems, and having heard Soul Superfly at length, along with Essence and Presence, I can give you my view of the differences between Def 2 and Superfly:

Some background as I see it, from the standpoint of a customer who has followed the company closely. In some respects, all of the work Zu has done in single FRD speakers during the past three years has been directed toward narrowing the performance gap between Definition and everything else in their line. When I first bought Druids and Definitions over five years ago, the two speakers were seriously different in character though united by a common thread of coherence and phase linearity courtesy of the wideband FRD. But Druid at that time was a "dark" sounding speaker, a little beamy while Definition 1.X was explosive, open, and sparkled. The first step to narrowing the gap was, ironically, the release of Definition 2.0. It removed the primary disadvantage Definition had compared to Druid at the time -- the Def's sealed MDF cabinet produced resonant glare at high SPLs, whereas the Druid's open "partial Griewe" cabinet had far, far less MDF glare when pounded with current.

Then Druid 4-08 opened up the top end, smoothing out most of the known non-linearity to the high-frequency contour of the simpler Druid, and removed much of the sense of compression under high SPL that separated that speaker from Definition. There was less directionality in Druid 4-08 as well.

Essence, a speaker not fully realized in my view, did force Zu to resolve several lingering limits in particular elements of their speakers, which while not known for outcome at the time, made Soul possible. First, with Essence there was a clear objective to fully implement the Griewe model for managing the FRD's backwave while keeping to Zu's ideal "1 square foot of floor space" mantra. This was achieved, yielding flat response down to 30 Hz from a single FRD architecture. Then, a ribbon tweeter was incorporated to improve top-end dispersion, linearity, extension and apparent speed. This decision, in my view, was less successful, but it made the speaker appeal to a wider audience than Druid. However, regardless how you feel about the ribbon supertweeter, accommodating it led to a key Soul-enabling improvement. The FRD was revised (though it mostly looks the same) in the variables of cone mass, motor strength and high frequencies management via the phase plug. The cylindrical phase plug, especially the machining of its face, enabled a single FRD Zu speaker to bahve much more like the double FRD Definition in terms of horizontal dispersion and high-frequency linearity. Some of this benefit was obscured by having to dial back the FRD's efficiency to match the less efficient ribbon, but the stage was set for the next project.

The low price point objective for Soul forced more innovation and a serious holistic re-evaluation of how Zu builds speakers. To get under $2000 required detailed re-examination of labor and how it's used, the prime cost factor. Essence was a breakthrough in Griewe implementation but the boys had to find a cheaper way to do it if they wanted Essence bass performance out of a speaker costiing half as much. As a host of a Zu house party, I saw and heard some early prototypes for varying directions and where Zu ended up is a loooooooooong way from where they started.

Freed from the constraints of matching a ribbon and returning to the familiar dynamic lensed supertweeter let Zu take everything they learned from Essence refinements to the FRD and apply to Soul, without detuning the main driver. So the motor got stronger and the cone lighter, with the new phase plug incorporated. The Zu-standard 101db/w/m efficiency is restored. They conjured a way to not only get *better* Griewe performance than from Essence (same bass response from a smaller cabinet) but to do it in a more affordable but not compromised package.

The net result is that Soul Superfly, specifically, is the single-FRD Zu speaker that most narrows the performance gap with Definition. It's more dynamically explosive than Druid and presents more scaled soundstage when the music demands it. There's enough weight to the bass underpinning to obviate the need for a subwoofer and the spatial discontinuity resulting when you add more boxes. Superfly has more of the openness and top end reveal that Definition does so well, and horizontal dispersion is much more like Definitions, so it doubles as an excellent home theater speaker better than Druid, in broad rooms with scattered seating. The overal octave-to-octive tonal balance is far closer to Definition's neutrality than was Druid at the start, and audibly better than Druid 4-08. Yet, Soul retains Druid's advantage over Definition in near-field listening and small-performance ultra-coherence courtesy of having only one FRD. The inimitable directness of Druid is fully retained for intimate listening while resolution pushes up the scale closing perhaps 40% of the former detail gap between Druid 4-08 and Definition 2.0.

Now, this won't last. Definition 2.0 is still easily worth its greater cost. And that cost multiple over Soul Superfly will make more people choose to settle with the simpler, smaller, lighter speaker. Another friend of mine here in Los Angeles took delivery of a custom-ordered pair of Definition 2.0 with the Soul-type FRDs. This is the only pair in the field with this configuration, AFAIK. They widen the gap and are better than my early Def 2s. The overall advantage of scale, ease, linearity and explosive dynamic rise intrinsic to the dual FRD Definition architecture fully inherits the advantages of the Superfly-style FRD, and so it goes. Plus, Definition will be redesigned completely, eventually.

Soul Superfly will never catch Zu's best but it is more than good enough to make the point that if you hypothetically can afford a system at the cost of Definitions + $2,000, a pair of Superfly on the right $10,000 of amplification will yield a more convincing stereo than a pair of Definition 2s powered by good $2,000 amplification. Move the spending scale for amps into the $3500 - $5,000 range paired with Definitions and the advantage moves to Defs plus, however.

Soul Superfly is game changer in how you allocate resources to a system and assemble it. It isn't a Definition but you can consider it a "Definition-enabled" Druid. At least until Zu figures out what to do in the middle of the line.

Does that answer your question? If not, ask for what's missing.


Thanks for such a comprehensive answer.

Back to the original post, I DON NOT thikng that the FirstWatt F1 will work on these. Unless this is a crossover-less design or will employ an active crossover with biamping.

Check out the F1 review on 6moons or the details on the First Watt site. A current source amplifier (F1 or F2 being the only ones in existance that I know of) does not play well with the crossovers present in 90%+ of all speakers.

There is no crossover in a any Zu speaker. In Soul, the amp connects directly to the full-range-driver, and the supertweeter is wired on a simple high-pass filter. The amp doesn't "see" a crossover at all. No dividing network before the speaker. It sees the FRD voice coil. The upper limit of the FRD rolls off electro-mechanically with intrinsic behavior.


One question I was hoping you could shed light on.

The freq graph on Zu's website for the Superfly is remarkably flat. So flat I do not believe it. And so flat in HF that it makes me nervous (as in the past I have not liked very flat high HF -- strange I know).

Do you believe those numbers?

Not that numbers are everything, or at times, anything.

I am just surprised that the small changes they have made created such a different frequency graph
Definition has always measured quite flat and yet it is a deeply toneful speaker. Flat-measuring speakers that get that way through complex crossovers with steep driver contouring do tend to sound like anything *but* flat and are irritating for many people (like me) to listen to, for other reasons than measuring "flat." It's all in how the designer gets to "flat" on the graph.

The Druid in some respects ruined Zu's credibility on measurements because Zu didn't measure it early, while some reviewers did, not understanding how to measure its real-world use. The infamous Canadian review of early Druid, in which the publication complied with Canadian practice of measuring a speaker suspended in mid-air, yielded a disastrously ugly graph that had nothing whatsoever to do with how a Druid sounded in a real residential room when properly set up. But the empirical audiophile brigade couldn't (or wouldn't) grok the fact that Druid's partial Griewe loading requires placement on a floor (you know, the way you'd actually use the speaker) with some attention paid to a fussy floor-to-plinth gap, in order to sound and measure right. Since then, Zu owners haven't cared a whit how the speakers measure, and Zu critics won't bother hearing them, or grant that they can possibly sound good, let alone great.

Superfly sounds like it measures, objectively. But since it gets to a reasonably flat graph without a crossover and most of its range is produced by one coherent driver, it won't sound like most flat-measuring speakers sound.

As the graph indicates, Superfly will be revealing. It is a bit more "accurate" speaker than Druid 4-08. A grungy amp will sound grungier on Superfly than on Druid. But the high impedance makes most amps, even grungy ones, sound better than they normally do, and not driving a crossover before the voice coil puts them on better behavior too. So Superfly is both revealing and forgiving, all things considered. But conversely, an excellent amp will be even more appreciated on Superfly than on Druid 4-08.

The changes over Druid aren't that small, given how much the FRD has been massaged. The full Griewe model seriously improves and extends bass, but it also affects the driver's performance well into the midrange. The cone and motor changes to the FRD make it considerably more vivid. The high-pass filter to which the supertweeter is wired is both more linear and cleaner owing to the selected components. And the cylindrical phase plug markedly linearizes and improve dispersion of the FRD's high-frequency output from the whizzer. What a lot of other designers would try to upgrade through multiple drivers and a more complicated crossover, Zu has attacked by refining the main driver's capabilities directly.

A frequency response graph is only a facet of a louodpeaker's performance indicative of an ability to transduce convincing music. It tells you nothing whatsoever about tone density, timbral acuity, dynamic aliveness, transient speed, spatial projection, phase coherence, or other non-frequency fidelity factors. And since the speaker's interaction with actual room and amplification factors aren't at all captured by frequency response measurements, you can safely limit how seriously you take such representations of performance.

Do I believe "those numbers?" Numbers imply a precision to speaker performance that's not remotely sustainable in actual deployment into a customer's system. It's not that I don't believe them. I believe Zu attained that curve. I just don't think it's relevant. Superfly sounds neutral and extended in the ways Zu's graph suggests. That's easily the least influential reason to buy the speaker over the myriad other speakers that also measure "flat." in the same price range.


sorry to join in the folks peppering you with questions, but here is mine:

i ordered a pair of mk-iv '08 druids a few years back. i loved just about everything about them. the sound, presentation, etc. i was pretty new to the high efficiency side of the hobby, but even got drawn into that. i could not, however, really get the druids set up in a way that worked in my room. i worked with a number of the folks there to try and get an ideal set up where i wanted them to live but fell flat. selling my druids was one of the few 'regrets' i had. even though i ended up with speakers that worked better in my room, i never like the sound as much.

you alluded to the souls being easier to set up. is it mostly driven by the design? i have since completely redone my room, changed the floors and walls and added treatment. just about everything sounds good in here now. are the souls that much less sensitive to placement? if so, i think i'm sold.

and, thanks for all of the impressions/thoughts/insights.


Can you explain the conflict between Druids and your room? What did you hear that led you to believe you couldn't "really get the Druids set up in a way that worked" in your room? Yet you ended up with speakers that worked better but you never liked the sound as much?

What didn't work about the Druids?

There are three things about the Soul that should make placement easier and more plug'n'play:

1/ Unlike the Druid's fussy floor-to-plinth gap adjustment, Soul is fixed gap on spikes and unless you have some exceedingly tall and stiff pile carpet, I can't see running into any gap problems. The tapered finger vents on the bottom of the cabinet do not need precise location above the floor for the Griewe model to work correctly.

2/ For some people, Druid's acoustic center was too far off the floor and the FRD radiated too much energy unimpeded by furniture and buman bodies directly to opposite surfaces. Druid also had a bit of directionality that gave it a narrower sweet spot than Soul. Soul's greater horizontal dispersion makes it easier to get good sound throughout the possible listening positions in a room. Soul puts the FRD less than 3' off the floor and its output is angled slightly upward. The acoutstic vertical center of the soundstaging is more natural for many people when seated, and its output is more in the dissipating and diffusing line of sight to the normal contents of a room., which is good.

3/ Soul has fewer aural anomalies than Druid, and bass is more extended without rumbling deep into the zone most rooms handle poorly. It's simply a more neutral speaker. The buying public at large seems highly sensitive to perceptions of bass output. Soul gives everyone less to argue about in that respect. It goes deep enough but not so deep as to cause real trouble. And its bass character is toneful, highly-defined and textured.


yes, i know that infamous graph, but i am not a graph-only guy (or i would not have druid).

i was thinking of essence stereophle graph which was pretty ragged too. soul looked so flat i cannot believe it.

TIM, try get better sound by jim smith. great book

I (or you) would have to ask Sean Casey about specifics on his frequency response/impedance graph. I haven't even discussed it. Perhaps the data informing the graph was normalized. Of course, to me, Soul *does* sound smoother than Essence, the "least Zu" speaker so far. But I've said straightforwardly I've considered Essence inferior to Druid 4-08 since Essence launched. I certainly never for a second considered giving up my Druid 4-08s for Essence, but I will replace them with Soul Superfly. But I understand why Essence appeals to a broader population.

There's a difference between ragged and wrong. I don't recall the Stereophile data graph on Essence (though I do remember something like JA conceding that it sounded to him as Art Dudley described, regardless of how it measured) but ragged response that shows short bandwidth abberations against a backdrop of general octave-to-octave balance can sound just fine and convincing, as opposed to a speaker with smoother curve but clearly visible octave-to-octave dysfunction, which can sound completely wrong.

At the end of the day, Zu's graph isn't actionable to me one way or another, but I've had the opportunity to both follow the speaker's development and hear at length in final form. It *sounds* about as smooth as Zu represents, but in a real customer setting it would never measure that way.

Hello to all from England,

I myself having only owned Zu speakers from early 2008 started with the Druid then progressed to the Essence in summer 2009.

Although I have not heard the Soul Superfly, yet. My experience with Zu speakers is that they show up anything that is wrong with a systems components, whether it be a defect or the tonal accuracy of the music.
Room differences can play a part, but these are usually very minimal, unless you have an overly damped room, then IMO you will not get what the Zu speakers do for the music.

I am currently running with solid state amplification from Rega with the Osiris and the Rega Isis CDP, which I find is a very good match/balance with the Essence over the Druid, the Druids sound very good on this system, but the Essence is a better match IMO.

I think Phil's posts and comments about tonal character of the system with Zu speakers is to be heeded, as this can make or break whether the Zu's work, this might change with the Soul Superfly.

Waiting in anticipation for the Souls to land in England.