Zu Druid questions

+++Broccoli gives me gas.+++ I'm having that reaction to all the chatter about "measurements". Lab measurements are so very useful-if everyone who bought the speakers set them up in an anechoic chamber with no furniture. I wouldn't find music nearly as entertaining watching it on a 'scope. IMO.

Jack,

I agree that your room at those dimensions are not doing the Ushers well. One thing I wanted was a better near field speaker, and would say that the Druids fit that requirement very well. My room is 19 x22 x 8 and I still thought the Ushers ( both 81's and 71's)could benefit from a larger space

Some interesting comments no doubt from all of us above, and we are glad to help. Let us all know what you ultimately wind up doing.

Ken

I read elsewhere they only did this with their top of the line model. If I decide to order I'll find out for sure.

I love the sound of my Ushers, but because of my living room and the big entertainment center, they're a beach to place. The slant and size make it difficult for me to get them out into the room where they can breath without the wife throwing a fit.

I was thinking the depth of the Druids might actually work to my advantage. I'm also seriously kicking around the idea of just turning this system into a HT and using a spare bedroom to set up a two channel rig.

Problem is this room is only 13'6" X 12'6" so the 6381's are a bit big, but the the Druids would probably fit in either situation. This would mean some major moves.

Oh no, am I looking for an excuse to upgrade yet again? :-)

Just to confirm, yes Zu does break in the speakers now. I saw the burn-in rack myself. I think Sean said they get 100 hours before they leave.

Good suggestion,Tvad. I think I read somewhere (6moons?)that Zu has started to break-in all of their speakers prior to shipment. Best to confirm that with Sean or Adam rather than just believing me.
And by the way, everybody, what's wrong with buying your speakers because you think they're cute or they match your vest or the butcher has a pair? We audiophiles make this kind of selection a matter of life and death. And we battle over a hair's breadth of difference between two products both of which stand a mile above Bose.
I think our anal obsession may be a good part of what keeps non-audiophiles from enjoying the music. For me this is a passtime, not a sacrament.

Hello everyone; I'm still here, but have just been reading a learning.

I appreciate the debate about this speaker and have not taken offense to anyone's post and hope no one else has either. Good spirited debates like this can be very helpful IMO. I'm learing much from both camps.

I know of no other speaker that could generate this many comments. I also know of no other speaker that seems to be at both extremes in people's opinions. I'm intrigued to say the least.

After vacation I may order a pair just to see. I don't mind paying the shipping, but my only concern is that I might not have enough time to get these broken in properly. One thing everyone seems to agree on is the long break-in period.

Please don't stop. It seems that I'm not the only one that's interested and this has turned into a very nice thread IMO.

I would be interested to hear what type of music you guys listen to. Perhaps this might tell something about this speaker as well, i.e. rock guys like them; classical guys don't.

Just wish there was an easier way to audition.

Once again, thanks so much for your time and responses. They are most appreciated.

Duke,

I appreciate your response as well. I agree that both ways of looking at things are important. I just feel that your ears should outweigh any measurement and test results. Yes, you can get some idea of what a speaker may or may not do in your system and environment by looking at its specs and lab measurements and maybe even reading some reviews, but I still think the only way to know for sure 100% if you will like it or not, is to get it in your room and throw some music at it. After all isnt that what this is all about? The music? :)

Sadly, yes, it is difficult for most to get an in home audition of any speaker of interest. I guess we all have to take chances here and there. Luckily there seem to be more and more manufacturers/dealers offering 30 or 60 day trials these days. That takes real confidence by a manufacturer like Zu...to say take our speakers home and listen to them for 2 months. If you arent fully satisfied, send them back.

Someone above asked what other speakers I have listened to and still decided to go with the Druids. Why have I decided to buy Druids as opposed to certain speakers I have listened too and can get at discounts? Several reasons...but mostly because of the way the Druids seem to present the music. Its hard to describe, but it was just more emotional and involving...maybe it was the room....maybe the gear...but it caught my attention. Have I been impressed the same by other speakers? Sure....but most of them cost many $$ more than the Druids...I would gladly rather have a pair of MAXX 2 or Summits....but right now, I will thoroughly enjoy the Druids in my system....now if I can decide on what custom finish to get....hmmmm....

F1audio, thanks for taking the time to reply. And I certainly agree that the rich variety of loudspeakers is much of what makes the industry so exciting. There's a wide variety of highly capable designers taking vastly different approaches - and perhaps I get overly fascinated by that. And often it is small companies - like Zu - whose innovations are pushing the boundaries.

I don't claim that measurements can reliably predict listener preference among dissimilar systems (electrostats vs horns would be an example), but that doesn't render them useless as an evaluation tool for audiophiles.

Take for instance the subjective assessment "speaker X sounds amazing!". That "amazing" can be expressed with greater precision: Voices and instruments sound real; you can close your eyes and hear the exact location of each instrument; you get the feeling of actually being in a concert hall; you can hear all the tiniest details even at low volume levels; the music conveys emotion and makes you want to dance; the bass hits you like Mike Tyson; and/or you can listen all day long and never get tired of it (perhaps dependent on how long you can stay in the ring with Mike!). Each of these "amazing" characteristics can be traced to something that the speaker is doing right, and it's doing it right because of its design.

"Just trust your ears" is great in theory, but what if the only audio stores you have reasonable access to are Best Buy and Circuit City? You'll have to rely on something other than your ears to decide which speakers are worth a major trip to audition, or are worth the risk of buying unheard. Reviews can be helpful of course, but once you're to that stage the more knowledge you have the better choices you're likely to make.

So the simplified version of my theory is this: If you know what qualities matter the most to you, and if you know what type of design is likely to produce those qualities and/or what measurements indicate their presence, then you can make better choices of which speakers are worth the trouble to audition and/or risk of buying without an audition (which is the circumstantial reality for many people).

In my opinion as brick-and-mortar stores become more of a rarity, "know thyself" and "know something about speaker design" are likely to become more important to the person embarking on his or her Great Loudspeaker Quest.

Duke

Duke -

I see where you are coming from. I do. It really depends on what "Y" is. For example, you could say that speaker "X" sounds "lean" because "it only has a 6" woofer and cant play low frequencies well".....that would be a valid statement and could be shown with graphs and tests (as well as just listening to the thing).

BUT if you change the statement to say something like "speaker "X" sounds "amazing" because of "Z", you throw any chance of explanation due to measurements out the window....because regardless of what any tests or graphs might show, the statement for the listener stands true....they felt that it sounded "amazing".

So while I agree that certain aspects of a speaker's performance can be generalized by looking at quantified data, those generalizations can easily be rendered moot by a listener's personal preference and opinion. My opinion that the Druid is a fantastic speaker that plays music beautifully cannot be overturned by a test result or a FR graph. So by your account, those measurements are inadequate or irrelevant. I would say irrelevant for sure.

So while you can explain with science why a speaker exhibits certain sonic characteristics in a given situation, you really cannot explain why one person prefers that sound, and another doesnt. Its a matter of personal taste....tubes vs. SS, electrostats vs. cones, digital vs. analog, etc...Zu vs. Usher...etc....thats the way it has always been, and always will be...and its what makes the industry so dynamic and alive. :)

Hey Jack...Jack!!! Wait!!! I need a vacation too!!

Kehut and Macrojack, glad to see we can still be friends even though if we don't eat the same vegetables!

Flaudio wrote something that I'd like to comment on:

"My point is that you cant draw subjective results from objective data. In other words, you cant say that product "X" sounds "Y" because of "Z"."

My question is, how can product "X" have sound "Y" without there being a cause, a "Z"?

Now I can understand how your experience with the Druids seems to support the position that measurements are useless. The measurements say one thing, and the reality you observed is something else - and you have chosen to trust your ears, not the graph! Good for you! But, maybe the conclusion you arrived at regarding objective measurements is off by a few degrees. There's another way to look at it: The measurements are showing too small of a piece of the puzzle to draw reliable conclusions from.

When there's a discrepancy between an accurate measurement and observed reality, the meaurement is either inadequate or irrelevant. You might want to go back and re-read the post by analytical chemist and Zu druid owner Ait. Among other things, he points out that a synthesis of seemingly unrelated data can give a useful (though imperfect) understanding of what's going on. [I grasp at frequency response and impedance curves, allusions to muffler technology, and subjective impressions (including my own) in trying to understand the Druids' bass system.]

With loudspeaker systems, the causes of perception are particularly likely to be complex and/or elusive. I can go into detail as to why if you would like. But given enough relevant pieces of the puzzle in my opinion it is possible to assemble a useful understanding of what's going on - what "Z" is.

Duke

---"Having 20 gourmet chefs doing the same taste test would give far more meaningful results as to the quality of the vegetable."---

What are the specs for a "quality" piece of broccoli? And how can 20 gourmet chefs decide whether YOU like the taste of it?

I have a respect and understanding of the need for extensive R&D, lab testing, and measurements of loudspeakers and other equipment. This is how loudspeakers are designed, engineered, and created. But when consumers are deciding on which speaker to buy, do they need to look at this data? Or can they simply go listen to several speakers and decide what they like best? Again, that is a personal preference. Some may choose to decide what sounds good by looking at graphs and charts...nothing wrong with that at all. Some might just take their favorite CD in to a store, play it on 5 different speakers, and pick number 3 because they were more emotionally drawn into the music than any of the other speakers. Certainly there is no wrong-doing there either. Different strokes for different folks. :)

This is why we have these "arguements" in audio....because it is NOT an absolute science. There arent concrete plans for building the ultimate music playback system. Anything that involves using our senses for determining any kind of result is going to be this way. Simply because not everyone likes the same smells, sights, sounds, or tastes. Period. No matter how many lab tests, blind tests, measurements are taken, the simple beauty of human individuality takes over.

It does matter what the gauges and measurements say. Two people eating broccoli isn't a well thought out measurement. Having 20 gourmet chefs doing the same taste test would give far more meaningful results as to the quality of the vegetable. In audio, progress is being made by those people who know how to design, analyze and then correlate test measurements with good sound. In other words, you have the intelligence to know what you're doing.

I wonder if Jack simply tired of all the rhetoric and went on vacation.

Which isn't a bad idea.

F1audio: I can only offer my opinion of the hour and a half I spent with Sean of Zu in his basement listening to the Druids. I was very impressed....enough so, that I am planning to buy a set....even though I work at a high end retailer and have access to virtually any other speaker out there.

I would be curious to know specific brands/models that you have heard and can say you'd prefer Druids to them. Thanks.

Agreed.

Jack, go get some Druids! ;-)

If you like the speaker or vegetable or movie, it doesn't really matter what the gauges, meters, formulae or critics say.

I understand this subjective view. However, whether you like broccoli more than potatoes is hardly useful to another in helping understand how either will taste. I believe there is a place for trying to objectively measure and describe performance just as their is a place for subjective hyperbole. While neither viewpoint tells the whole story (and how one may personally react to Zu Druid's sound), IMHO there is space and value for both views on these forums, rather than dismissing all measurements as..."it doesn't really matter".

Once again, let me reiterate how great Zu Druid speakers are. This is not an attack on Zu Druid's fine speakers. I am defending measurements which seem to be so easily dismissed as useless on not just this thread but many threads on these forums.

Duke,

Thanks. I did get that part of your post, and appreciate the support for explaining how the Druids can sound despite the measurements, especially those specs that appear in the review of Soundstage.(I have some thoughts on that at the end of this post.) I have always loved reading your threads and respect your wisdom and understanding of speaker designing and building, and comments from you regarding the Zu's interesting and intruiging designs are a great resource and welcomed info.. Not something everyone (especially me) can do, and do well. If anyone is qualified to ad anything helpful and constructive here it definitely is you.So, no dis-respect to you.

My rant is only due to the limited comments from those who have actually listened and compared by their own experience, in their own systems, the speakers the orig. posted lsited as asking for help with, namely the Usher 6 series and Klipsch in particular. I just see so many comments, and so little real info and answers of what was being asked for.

I assumed the orig. poster saw many threads as mentioned in his post, and had a chance to read them..but alas, some here are quick to take a "ho-hum"..here we go again stance. Did they own 6 series Usher or Klipsch speaker and then own Druids to make a fair comparison?? If so, they dont say such was the case. That really was my main point in my rant.

I will say this as to the Druids. They are critical as to set up, regardless of those that feel they are easliy placed within the room. I have read that they can be placed very close to the front wall and sound great, but like most designs I have used, they are much better placed well out in the room. The Cardas ratio seems to work well in my instance. I think many give up, or are unwilling or unable as the case is, and thus sell them, perhaps too soon, without taking the time to work with them, place them and toe them for best sound. Once set up and tweeked and fed good electronics, they shine nicely.I am floored at how much good bass there is in the speaker!

Anyway, thanks and apologies to all for my rant. ;-)

Regards,
Ken

F1audio made my point much better than I did.
If you like the speaker or vegetable or movie, it doesn't really matter what the gauges, meters, formulae or critics say.
All that counts is that you are enjoying yourself. The Absolute Sound paradigm has completely distracted us all away from our own judgement. It's like letting Hugh Hefner tell you who to marry.

Sorry to those affronted by "grandstanding" with unecessary detailed discussion here on the Zu Druids. As several have pointed out and continue to reiterate "measurements have no meaning", as the Zu Druids are a fantastic speaker irregardless of what a lab measurement would indicate (better than all other high end speakers according to F1Audio) and Sean is a great guy. I don't dispute any of this. For the record, I already stated " Zu Druid's are undoubtedly good speakers."

I understand the need for subjectivists to jump in and aggressively defend preferences given that they select audio equipment without heed to measurements. On the flip side, please understand that objectivists enjoy and learn a lot through technical discussions with people such as Duke.

I can only offer my opinion of the hour and a half I spent with Sean of Zu in his basement listening to the Druids. I was very impressed....enough so, that I am planning to buy a set....even though I work at a high end retailer and have access to virtually any other speaker out there.

My take on the "subjective/objective" debate that seems to pop its ugly head up a lot is that musical enjoyment is a taste. Take 2 people, some broccoli, and some lab equipment....measure 2 pieces of broccoli to ensure they are identical, then feed them to the 2 people. One likes it, one hates it. How do you explain this? In short, you cant determine that broccoli tastes good nor bad by measuring it. Period.

My point is that you cant draw subjective results from objective data. In other words, you cant say that product "X" sounds "Y" because of "Z". Because no matter how many people agree with that statement, there will always be someone who disagrees. And no matter how small the minority may be, they are right as well. End rant. :)

Kehut,

The original poster said that the Druids "have peaked my interest". I didn't read that as excluding interest in all commentary other than a direct comparison with Usher and/or Klipsch speakers.

And... well, I don't know any other way to say this. Since when is talking about speaker design on the "Speakers" board in a thread about a speaker with an intriguing and mysterious design "grandstanding"?

Kehut, not everyone shares your belief system that "scientific measurements dont offer any help at all as to the sound of any speaker". (Have you run that by Sean and Adam?) I guess you missed it, but what I was doing was explaining to the best of my understanding (given the lack of published design details) how the Druids can still have decent-sounding bass when they measured 25 dB down at their rated low frequency limit (38 Hz) and have a similar notch at 150 Hz. On paper, that really is abysmal performance. Come on man indeed... I was trying to keep your speaker in the running in the eyes of someone who may still give science some credibility.

Duke

OK, I'll remember from now on:
No digressions from simple answers to simple questions.
Thanks for filling me in on the rules here.

Macro...I agree completely!! Why does this happen so frequently? I posted my impressions of the Zu's sound in comparison to the Ushers as the original posted requested...NO one else makes mention with the exception of Mondonitro about how the Ushers compare or that they heard them at all.

Look you are all entitled to your opinions and offer your suggestions, but lets keep to the posters query,and not make it a platform to grandstand your knowledge of speaker designing,, share scientific measurements that dont offer any help at all as to the sound of any speaker, much less a comparison of two differnt designs, or bash a very sucessful company (Zu) who got it right and still has many detractors who cry over that fact.. Im sure Mr. Jack Dotson is left scratching his head over all this...come on man!

Sorry, guys. I didn't mean to attack anybody but time and again I have seen these simple requests turned into engineering dialogues which completely abandon the original poster. I suppose if he were to come on board and request clarification this might make sense. As it is, I believe he has been left high and dry.
For a few of you, the emphasis seems to be on what went into the speaker but you may be surprised to learn that most of us only care about what comes out of it.

Macrojack,

The issue of the SoundStage measurements came up. I posted a possible explanation. Note that Zu hasn't really described what their enclosures do, so we are left to surmise - and note also my request for clarification and correction on the specifics. Is trying to understand the SoundStage measurements and correlate what little we know about the encloure design with subjective impressions really so out of place as to be called "hijacking"?

I'm going to do it again, just so you know. Shadorne commented on a similar-looking frequency response curve in a PMC loudspeaker as possibly shedding light on the Druid's design. I'm going to reply to him.

Also, just so you know, it's not the numbers themselves that I value. It's the knowledge and insight that can be conveyed if you understand what the numbers are saying. I wish to understand loudspeaker design (and the Druids are a particularly interesting design), and I wish to share my understanding with others who are interested in loudspeaker design. If you feel I have mischaracterized the Druids in some way, by all means take me up on my request for correction. If you just object to my interjecting numbers and science in general, I invite you to start another thread and we'll discuss it.

Shadorne,

Thanks for bringing up SoundStage's measurements of the PMC speaker. I think there's some information there that may shed light on the mysterious Druids.

The PMC is clearly a tuned pipe enclosure - in this case a transmission line having a factory-specified line length of "2 meters". The midbass notch location would lead me to expect a line length of about 2.15 meters, so the specified line length corresponds pretty darn close with the location of the notch. I think the notch is too severe and too low in frequency to be related to an internal resonance. It looks like what I used to get in some of my transmission line designs. I'm pretty sure the PMC woofer has a higher Qts than the fullrange driver in the Druid, which would be consistent with the PMC's measured response holding up better below 100 Hz.

From the location of the notches, we can conclude that the PMC and Druid have similar path lengths. The PMC uses a three-fold transmission line. We don't know what's inside the Druid yet. Maybe one of these days I'll try to map out the internal partitions by knuckle-rapping.

There's something else we might gain insight into from a comparision with the PMC measurements. Take a look at both impedance curves. You see how the Druid's impedance peaks rise up much higher in the bass region? My guess is that's partly due to the Druid having relatively little damping material in its enclosure. Now some of the difference could also be due to high a high mechanical Q (Qms) of the Druid's driver, but even a little damping material in a tuned pipe should bring those peaks down considerably. I'm not saying there's no damping material in the Druid, but what's there is evidently not very effective at low frequencies (intentionally, I would guess - the impedance curve may be an indication of the design's muffler heritage).

By looking at both speakers' frequency response and impedance curves, I think you can see a family resemblance. Something similar to the PMC's transmission line - but obviously not identical - seems to be going on in the Druid's enclosure.

Duke

Duke,
Please take note that people ate before they began tinkering with agriculture. I'm not sure my correction is any more pertinient than your analogy attempt but I felt like pointing out that discrepancy.
Now, as for science, I am well aware that scientific data and techniques were applied to the creation of the Zu designs. What I am mocking is the ongoing second guessing so many of you feel qualified to apply to other peoples designs. Jack is asking for fellow members to share any experience they have with two specific speakers. He is not seeking prognostication. I've reread his post and he has not asked for opinions of what the speaker SHOULD sound like based upon an educated guess. The whole laboratory/measurement debate is stupid but if you are one who values those numbers, hell, it's your money , do your thing. I'm sure a lot of people will jump to your defense at this point and Tvad will surely scold me. Nonetheless, I maintain that the lab talk should be witheld until requested. It muddies too many discussions and hijacks too many threads.

Shardone - Some of this or that might be related to rainbows and puppydogs. If the driver is breaking up anywhere in its band I can't hear it. You couldn't either.

When the frequency response becomes very spikey above a certain frequency cone break up is often the explanation. The fall off in off axis response is probably beaming. IMHO the "whizzer" cone is there for a reason.

As Duke points out...our hearing is remarkably well able to deal with notches in the frequency response (spikes are actually much more acceptable than sustained drops)

So the break up may not be audible.

The uneven power response: Although the "whizzer" fixes the on axis to a large extent....I expect that the roll off in off axis response above 2 Khz will be clearly audible. The speaker will probably sound different as you walk from directly in front to 45 degrees off axis - this is not a bad thing - just the way it will behave and will make speaker positioning/toe-in quite important - thats all.

Duke,

I agree with you. Underdamped/high Q design is a much better explanation for the severe notch at 150 HZ. The cone will respond to cabinet resonance.

Here is another example PMC GB1 of a speaker with a similar notch.

There is a superficial similarity in the tall narrow cabinet dimensions and overal response, however the GB1 is crossed over on the tweeter much lower and therefore has a more even off axis response at higher frequencies.
PMC = 6.1"W x 9.21D x 34.25" H
Zu Druid = 10 1/2"W x 6 3/8"D x 50"H

I agree that the notch at 150 Hz will likely be inaudible - many rooms may have sharp notches like this anyway from wall reflections/modes - so no big deal.

However an underdamped design will differ quite audibly from a critically damped design. As you suggest, longer oscillations in the low end may give more of a bass impression than the frequency plot alone may suggest.

----------------

All goes to show that measurements are meaningful and do tell us something about the design and the performance.

Of course, I would NEVER recommend to select a speaker based on measurements alone. Nevertheless I would not recommend to stick ones head in the sand and totally ignore meaurements either.

Let me finish by saying Zu Druid's are undoubtedly good speakers. The high efficiency and dynamics from this design is likely to be extremely impressive even with very modest amplification power. My intent was never to bash these great speakers. Sorry if it sounded that way...but I was only trying to defend the value of measurements.

Ait,

Thanks for the input from your perspective - that of someone with a professional scientific background.

Here's a link that talks about an effort to better correlate measurements with perception in audio by means of a psychoacoustically-weighted metric derived from several different measurements, but focusing on the shape of the transfer function rather than on spectral changes:

http://www.audiomasterclass.com/learn.cfm?a=3651

See also Audio Engineering Society preprints number 5890, 5891, and 6888.

Duke

As an analytical chemist for over 25 years, I know that there are many measurements one can make of a system, be it a chemical system, a biological system or a sound system, and that we do not have measurements that explain every phenomenon precisely. Measurements are useful to describe certain aspects of a system, but rarely do they descibe a system fully. We do the best we can with our existing tools and try to invent new ones to make the measurements the existing tools can't. New tools such as informatics and chemometrics allow us to take many seemingly disparate measurements and synthesize them into a representation of what is truly important about a system - for example, one can take measurements of a person's blood, breath, urine, etc. that are fairly useless in and of themselves and through some chemometric data treatment actually diagnose that person's health, and what diseases they may be susceptible to.

As a Zu Druid owner, I know that the published measurements seem to show something that should sound pretty bad, but the Druids absolutely SING to me. Perhaps we need some new measurements, or some ways to treat the data from the old measurements so that we actually determine the true capabilities of the system.

I don't really understand audiophiles belittling science. That's like people who eat belittling agriculture.

Now there are discrepancies between commonly used measurements and subjective preference, but that's hardly a secret. The applicable term is "psychoacoustics", and guess what - it's a science.

If a product works and sounds good, it's because somebody got the science right.

Duke

Bob_reynolds, you are exactly right.. pretty little hardware, big snake like power cables... much is just marketing hype in the audiophile world, that is the good thing about Zu actually as you point out,, They are directly derived from the PRo arena and concepts used in live pro equipment, and the designs use Pro drivers, designed for a purpose period, without all the extra frills and correction circuitry needed with mainstream audio drivers. But of course they had to break down and start adding pretty colors, machined custom plates etc, to look like a hi end product, but all the money is put in the right place with Zu designs, the Performance, reliability, and sound.

What is the value of all this speculation about whether of not the Druid design should work? It clearly works for a lot of people. "Science Says" is a fun game for awhile for a certain sort of person but the proof is in the listening.
I have no expertise in speaker design but I have wondered if the unusually short excursion of the full range driver could explain anything about the success the Druid enjoys. The driver movement is not visible until you reach very high listening levels and then only slightly.
Also, why should the diameter of the driver be a limiting factor? The QUAD 57, to which I hear the Druid compared sometimes, has a much larger radiating surface. Does it also defy the calculations of our critics? Or does it also benefit from very short excursion? Is it transitional speed that benefits both in defying projections that should limit them?
Maybe it is possible that Zu started out with a design that should not be able to work and manipulated it in such a way that it works quite well. I don't know their secrets but I remember being told that they took old technology and found ways to improve upon it using modern tools and materials. Maybe they did that. Maybe not. Still, the speaker is a marvel and deserves investigation. If it turns out you don't like it, you will have had some fun experimenting and you will be able to provide us with an educated and informed opinion.

jack,,you still have great speakers

I have built underdamped pipe speakers, and speculate that the Druid's enclosure may be a variation on an underdamped pipe.

The 150 Hz notch would indicate an internal path length of about 90 inches. When the path length is equal to one wavelength, the backwave energy emerging from the end of the pipe is 180 degrees out of phase with the front wave of the driver, so cancellation occurs. The depth of the notch makes me suspect the line is underdamped. Note that the ear is much more tolerant of frequency response dips than it is of peaks; without that SoundStage measurement, I bet very few people would know it's there.

Brave move on the part of Adam and Sean, sending their speaker to be measured when I'm sure they knew full well that its measured response would raise eyebrows.

If the 90 inches ballpark path length is correct, we'd expect to see a local response maximum at about 75 Hz, with response rolling off slowly to about 37.5 Hz and then falling off rapidly below that. This is reasonably consistent with the SoundStage measurements.

To my ears, the Druids sound like they have much more bass than the SoundStage measurements indicate is possible, even optimistically factoring in boundary reinforcement.

Normal boundary reinforcement will of course bring up the response in the lower octaves, but not all that much. I do not understand why the gap between the vent and the floor is so critical, but can accept that it is. Zu claims to use muffler technology invented by a man named Griewe, which I have been unable to find details of so presumably it's not patented. Mufflers.... hmmmm.... Jackson Browne.... hmmmm....

There are two ways to bring up the apparent loudness of a signal. The most obvious is to increase the intensity, or sound pressure level, of the signal. A less obvious way is to make the signal last longer. If presented with two brief signals of equal intensity but different duration, the ear will perceive the one lasting longer as being louder. Perhaps the muffler-like characteristics of the Griewe enclosure take advantage of this psychoacoustic phenomenon, filling in the perceived bass a bit by sustaining bass energy for just a little bit longer. "Oh won't you staaaaaay, just a little bit longer...." This is just a SWAG on my part, and I invite clarification and correction from anyone who knows better.

Duke

In the real world of sound, the druids sound like a superior speaker to many regardless if people are stuck on some crazy thoughts that a guitar will sound like a violin thru or something crazy... They easily exceed real world listening conditions in the application, even over some of the best Altec lansing Computer speakers :) (last part was a sarcastic joke) Try them to learn the truth for yourself..

These are an extremly sucessful speaker so don't get caught up listening to all the static noise coming from behind your computer screen and pool of internet speculation, most companies would be out of business if most of the stuff shown was true or truley effecting performance... Take K-horns till this day people don't believe the design is really any good, and the are still one of the better most popular classics, it was seen as nutty at the time too from reading the history on it. Yep you need Corners to make them work or they are pretty much crap.. same issue applies here, but nowhere near the Requirement to put you speaker on a floor vs. having open corners!!

Ha! A question on how the measurements are flawed turns into a discussion of them. I'm not sufficiently adept technically to answer these questions completely, but I'll speculate wildly (something I'm good at too).

Shardone - Some of this or that might be related to rainbows and puppydogs. If the driver is breaking up anywhere in its band I can't hear it. You couldn't either. Placement of the Druids is incredibly flexible without changing the character of the sound. Hanging the Druids in free air would probably have been acceptable had they bothered to load the chamber with an attached hard plate at the base of the speaker AS IT WOULD BE IN ANY LISTENING ENVIRONMENT.

Bob - I don't know of any technical literature related to their proprietary "Griewe" loading technique. I do know it is distinct from other ventilation schemes. Where horns have wall-distances they prefer, as well as bass reflex designs, the Druids have an ideal floor distance. They don't care much how far they are from walls. Druids are extremely coherent. Blame the faulty graphs, not the speakers.

Bear in mind also, these measurements were made on a two-generations-old model.

I don't pretend Druids are perfect for everyone, but misinformation and derivative speculation should stop.

I bought a pair of Zu Definitions sight unseen. I auditioned a number of other speakers and enjoyed a few that would have made me very happy. Two things impressed me abut Zu speakers: (1) the passions that they elicited - both positive and negative and (2) the fact that Sean or Adam answered the phone at ZuAudio and were very open about answering questions. Plus they fit my "needs list" for size, ease of positioning, off-axis listening, ability to fill a room with sound, full-range, ability to handle almost any type of music, visual appeal, etc.

I must admit to being also seduced by the full refund policy. However, once the speakers arrived, I realized that this was merely good marketing. Returning them would have been much more than a mere annoyance, it would have been a royal pain, something that I immediately factored into the decicion to keep them.

The current state of audio is confusing; there are a lot of good speakers available at all different price points rather than only correct one solution for each situation. Once I realized this, I stopped looking for the one perfect speaker, the only one that could possibly fit my needs. I gambled a bit, and an quite pleased that I did; but not everyone will agree.

The problem with the Soundstage measurements was that they hung the speakers in free-air, per standard protocol. They were informed of the speakers' need for floor loading but they were unwilling to break procedure to measure the speakers. The effect was akin to removing the port from another speaker and enlarging the hole

I looked at the soundstage measurements and they don't look at all surprising. Looks like the 10" cone is seriously breaking up above 2KHz (as one would expect); the whizzer ameliorates some of the on axis response in this range but not the off axis response.

The sharp drop in response at 150 Hz might be related to a cabinet waffle or box resonance (cancelling the speaker primary response). It is indeed possible that firmly placed on a solid floor (spikes through a carpet) that this resonance might be better damped (improvingthe bass).

Anechoic measurements are always performed in a way that minimizes effects from the room. It is the only way to make a standard measurement.

Placement/sweetspot of this kind of speaker may be absolutely critical. Just my two cents...based on the measurements (superficial comments and much speculation of course - so don't take this very seriously).

The problem with the Soundstage measurements was that they hung the speakers in free-air, per standard protocol. They were informed of the speakers' need for floor loading but they were unwilling to break procedure to measure the speakers. The effect was akin to removing the port from another speaker and enlarging the hole.

So the measurements were valid, assuming you hang the speakers from the ceiling. Any Druid owner will tell you that floor-gap is critical in tuning the bass. 1/4" makes a huge difference and having a hard surface under the speaker is crucial. If placing on carpet, an "artificial" hard tile or such will seriously improve bass response.

I'm a Zu guy, having owned the Druids, Def. 1.5's and Pro's. But, not everyone is. The strengths of the Druids will not easily be surpassed anywhere near their price, but lots of folks have different sets of priorities which don't align with them. Those folks will leave saying "I don't get it". That's OK, but somewhat of a pain if the speakers were purchased for the audition.

The advice of hearing them first is good. Try to make it as lengthy of an audition as possible, as many who have been through my room say it took a little time to lock on but that they really dug it once they figured it out.

Some folks can't imagine "going back" from Zu, others can't imagine "going to". There's no way to know without taking 'em for a spin.

Oh yeah, they *really* like tubes!

Listening before you buy is unnecessary advice with the Druids except when you buy used. New Druids are only available from the Zu factory and they automatically provide you with a 60 day return option. If you don't like them, you will only have spent round trip shipping. Call Zu for a precise shipping quote and you will know how much money you are risking.
In the case of used Druids, they appear to sell immediately for their asking price so I should think the financial risk there is even less than for new ones.
If you choose not to keep them, think of the expenditure as a 60 day rental fee or as the cost of research. In either case, U.S. buyers will find the gamble insignificant. Shipping is surprisingly cheap via FedEx ground.

Jack,

To answer one of your questions, the Druids sound nothing like Klipsch. They are very, very different. I have owned the Druids, extensively auditioned the 6381's, and currently own a pair of vintage Cornwalls in a 2nd system. Nutella is absolutely correct in his post. Druids are very nice, and Zu is a great company. The Ushers are also very nice. It's tough to say which you'll prefer. Audition before you buy, or take advantage of Zu's in-home trial. Do not, however, sell your Ushers assuming you'll like the Druids better.

Jeff

you have great speakers.