September 2002Zu Cable Druid Loudspeakers
by John Potis
One of the things that fuels interest in high-end audio is the vast array of available choices. Tubes, solid state, hybrids, horns, planars, electrostatics, dynamics -- audio equipment comes in a staggering array of sizes, designs and sonic flavors. Nobody can complain about cookie-cutter products or a lack of fresh ideas. Nevertheless, its nice to see new companies trying something different.
From the beginning, Zu Cable had its own ideas on how best to go about designing speakers. Believing that dynamics are as important a performance parameter as any other, they made their design goal a relatively full-range speaker of high efficiency and resolution. They broke down their quest into three different design challenges: a full-range driver with high dynamics and good sound, an enclosure with proper loading, and a signal-delivery system (speaker cable) as good or better than any on the market.
Zu Cable sought a driver thats high in efficiency and low in mass, and would minimize noise. By strict definition, lower noise levels should translate to higher resolution. The $3600-USD-per-pair Druids nearly full-range 10" driver is a proprietary design constructed in-house from purchased components made in the US. Zu Cable claims a very low moving mass of 25 grams and a very high motor strength --with very tight tolerances. They also claim dramatically reduced high-frequency lobing through proper cone shape and structure, which includes the use of a "whizzer" and center wave guide. They contend that a properly engineered full-range driver can combine linear amplitude response, wide bandwidth, high sensitivity, linear impedance (when properly loaded), high SPL output, and little or no dynamic damping.
For a fresh approach on the enclosure, Zu Cables Sean Casey teamed up with Ron Griewe, a life-long motorcyclist and motorcycle engineer with several original cycle-related designs to his credit and 14 years as editor-in-chief of Cycleworld Magazine. Griewe had already invented and engineered an exhaust design that enabled an internal combustion engine to develop more power with less noise. Casey obtained permission to use Griewes research for loudspeaker applications in an effort to push the envelope with a speaker that developed more power with less noise and a broader usable bandwidth. Additionally, Zu Cable claims increased low-frequency efficiency, increased control over the driver, reduced internal noise over ported designs, reduced group delay, and more linear overall electrical impedance.
Then there was signal delivery. Zu Cable turned to their own Wax speaker cable for interface with the amplifier, and the companys B3 connection scheme is a very new wrinkle as it utilizes the unique locking Neutrik connector. The design and specifics are proprietary, but the reasons for the B3 connection stem from the fact that the Druid loudspeaker is a completely crossoverless design. Wired internally with Zu Cables Wax cable, there are absolutely no components of any kind between the speakers Neutrik input connection and the primary drivers voice coil. When you use Zu Cables Wax speaker cable, the Neutrik eight-pole connector offers a straight-line connection between the amp and speaker drivers without altering the cables unique geometry, and thus the B3 offers the most direct and unadulterated connection possible between your amplifier and the speaker. But for those who have already invested in their own cables, Zu Cable has graciously included a pair of high-quality Cardas binding posts that feature unplated pure copper contact points but dont accept banana plugs -- spades only.
The Druids midrange/bass driver is fairly full-range, but it does enlist the aid of a 3/4" Audax soft-dome super tweeter at 12kHz utilizing a first-order 6dB per octave slope. The Druid is quoted as having a 12-ohm load and a sensitivity of 101dB, but Zu Cable says the speakers are "realistically rated at 300 watts RMS and are not specifically marketed to tube owners." The Druid uses a unique venting system (vented from the bottom of the speaker) that Zu Cable fully explains on their website. Claimed frequency response is 45Hz to 25kHz (-3dB).
I was struck by the fact that for the product of a new company, the Druid was solidly constructed and beautifully finished. The spiked, brushed-aluminum plinth on which the speaker sits is attractive and well designed as it stabilizes the speaker nicely. The review pair of speakers came in a very nicely finished high-gloss red. The Druid measures 10 1/2"W x 6 3/8"D x 50"H and weighs 60 pounds.
Zu Cable included with the speakers a pair of Wax cables terminated with spade lugs on one end and the BC3 interface on the other ($650 for a 10' pair). While I used the Wax cables whenever I used the Druids, I didnt get the chance to try to compare them to other cables due to the fact that the BC3 interface precluded use of the cables on my own speakers, and its difficult enough to grasp the intricacies of a new speaker without trying to use them to assess the relative virtues of different speaker cables.
Sources during the review period were a Pioneer DV-535 DVD player used as transport to feed a Bel Canto DAC1.1, and a Sony SCD-CE775 player for SACD playback. The preamplifier in use was a Herron VTSP-1A, and amplifiers included Opera Reference 9.9A monoblocks and an Audio Research VS55, with extensive use of the Audion Sterling integrated amplifier. Interconnects were the JPS Labs Ultraconductor as were the single-run speaker cables. Accessories included Vibrapods and the Audio Magic Stealth power purifier.
After trying several amplifiers with the Druid, I settled on the Audion Sterling EL34 integrated amp. The Sterling is a reasonably priced 12-watt SET integrated amplifier utilizing a pair of EL34 tubes to produce a warm and rich sonic character. Its also the sort of amp that will likely be used with the highly sensitive Druid.
I found room positioning as important to the Druids midrange as to its bass. Just drop them where you are accustomed to placing speakers and you run the risk of not getting anything close to what these speakers can offer. I spent many hours not getting the best from the Druids before I discovered the correct positioning in my room. Sitting close to the speakers, I found the midrange could be a little grainy and male vocals could be left unsupported through a slight suck-out in the lower midrange. Deep bass also benefited greatly through closer proximity to the wall behind than I generally use -- about one foot closer, which put the face of the speakers 35" from the front wall.
Zu Cable makes much of the Druids dynamics, and this aspect of the speakers sound is something to behold. The Druids can fill a large room with just a handful of watts. But thats not what I would call the Druids biggest draw. Ive found that efficient speakers can generally play loudly, but what they also excel at is playing softly. Many speakers, particularly ones that are difficult to drive, can play as loudly as the Druids, but they wont get your juices flowing until you pump a lot of juice into them. At low or middle volumes, they generally sound lethargic and unexciting, often obscuring inner detail and slurring microdynamics. Not the Druids. At whisper volumes, you get from them most of what is important in the music. Inner detail is very good, and though bass power is largely absent, the speakers balance is unchanged.
Speaking of bass, it is the Druids nether regions that will probably be the deal maker or deal breaker for most people. The Druids are not a small speaker, and given their large 10" driver, they are noticeably light in the bass. This is perhaps a design compromise made so that the overall efficiency could be maintained without mandating an enclosure the size of a refrigerator. While the Druids track very well into the upper bass and do well in the reproduction of both electric and acoustic bass, they fall off pretty quickly below that region. The Druids largely ignore deep bass drums and other subsonic effects. In terms of extension and bass power, the Druids are about what one can expect from a very good stand-mounted speaker or a smallish floorstanding one.
The only nit I can pick with the speakers midrange is that its not quite as smooth and flowing as that of my reference speakers. The Druids do produce just a touch of grain -- not a lot, but a touch. On the positive side, the midrange is very clear and articulate. And when I say articulate, Im not just talking about a speaker that doesnt slur its speech; Im talking about a speaker that articulates in the dynamic realm like very few can. When the music calls upon the Druids to do so, these speakers climb up in your face and shout at you -- try Becks Odelay [DGC DGCD-24823] for an example. This is a function of excellent microdynamic capabilities. Where most speakers seemingly gloss over such detail, the Druids dont. They track it accurately and put it right in front of you. On cue they can surpass any speaker that Ive had experience with in the area of getting crude and rude, and then at the change of a CD they return to a generally polite demeanor. Its actually something to hear as the speaker does rare artistic justice to both Vivaldi and Van Halen.
The treble region of the Druid is largely what you make of it through positioning and amplifier choice. Through its money region, the treble originates from the 10" driver, which makes it pretty directional even though the aforementioned whizzer cone and wave-guide aid in this regard. Though the Druid has broad enough treble dispersion to sound generally good throughout the room, it is directional enough to "tune" through judicious toe-in. How much toe-in I used depended on which amplifier I was using. I started with the Audio Research VS55 and used the speakers with very little toe-in at all. Later, when I switched to the Audion integrated amplifier, I gave the Druids much greater toe-in, to the point where the speaker axes crossed just behind my head. Generally, I found the ARC amp a poor mate with the Druids as the treble was razor sharp and piercing. My own Herron M150s and the Audion Sterling proved much better matches.
One day I decided to move the Druids into my larger family room. I wanted to hear just how loudly they could play without obvious distortion, but the first thing I noticed was how nice they looked in real living quarters. What I discovered was that in my roughly 18' by 25' room, the Druids could play plenty loud. Really loud. The problem was that in that room they really did need a subwoofer. They just couldnt supply enough bass for a balanced presentation. The good news is that with a sub, even the inexpensive Polk PSW550 that happened to be available, the Druids gave me more clean and balanced SPLs than Ive ever wished for. I had no problem mating the Druids with the Polk sub, and together they made for a presentation that was extraordinarily clean and precise no matter the volume level I chose. Together they sounded like much larger and more powerful (and expensive!) speakers. Of course, they were also providing this on just a few watts from the main amplifier.
Back in my smaller room and without the sub, I cued up James Taylors Hourglass [Columbia CK67912]. I patiently waited until "Gaia" came up. Not that an extraordinary amount of patience was required. Cut after cut was pleasantly reproduced, and what I heard was a smoothly balanced presentation with focus placed in the center of the audible spectrum. That bass was warm, clean and fairly well detailed, just not very deep. But it was also nicely balanced by the treble, which was surprisingly polite and had a notable lack of glare or edge.
Once "Gaia" began, several things struck me. First, the soundstaging was wonderful. It was deep and wide and extended well behind both speakers; it also filled out the rear corners of the room nicely. It was also tall and spacious, though not quite as open and airy as with some other, albeit more expensive speakers Ive been using. Very nicely done, actually. Taylors voice was firmly centered between the speakers, though not as sharply focused as it could have been. His voice was lacking a little of the fullness that I mentioned earlier. While not honky at all, it was simply missing some of his resonance in the lower registers. I wont use the word nasal either, but the voice was slightly thinner than usual. I also noticed that the ride cymbal on "Up From Your Life" was present and smooth enough, but it did lack some of the delicacy a dedicated midrange/tweeter combination may bring. These are small aberrations, to be sure, but I cant say that they bothered me much because of other things the speakers could do.
After that, things got better and better. Very important to "Gaia" are the electric bass lines. What the Druids did was reproduce them very clearly with excellent tonality and body. No, the traveling bass drum near the end of the song didnt possess the kind of weight and authority that a lot of other speakers could bring to the table, but two things arose from the midrange to give the song a new focus: first was the alto sax. Its absolutely blissful melody originated at center-stage and then radiated outward in all three dimensions until it reached an almost celestial presence. Then there was the piano that was as articulate as it was spacious. It really was as emotionally charged, or more so, than I ever recall. I was suddenly given a new appreciation for the song I previously thought of for its bass drama.
One CD that I thought the Druids were going to do complete justice to was The Complete Louis Armstrong & Duke Ellington Sessions [Roulette/Capitol CDP 593844], and I was right. The recording has a somewhat dated sound, which is limited at the frequency extremes, and soundstaging is bunched up in the middle, but the midrange is superb, with Armstrongs vocals properly captured. "Dukes Place" made the Druids sound most eloquent. Stand-up-bass lines were clearly discerned, lacking only in the lowest "power zone" but very musical nevertheless. Armstrongs trumpet was penetrating (in a good way), as was the coronet. Armstrongs voice was positively arresting in its clarity and transparency, and I could clearly hear what made Satchmo Satchmo.
Hardly suited exclusively to vintage jazz recordings, the Druids were good with something a little more modern and raucous too. Pearl Jams Ten [Epic ZK 47857] seemed like a good choice. Somewhat surprising was the job the Druids did on "Alive." The presentation was up front and in my face, as it should be, and by this time I had the treble dialed in such that the speakers were bright enough to be exciting but very much lacking in a real fatigue factor (this wasnt the case early on). As expected, the Druids handled the program material with total aplomb, providing a hard-driving performance. Vocals were forward in the mix and very well done. And what a soundstage the Druids threw on "Black": deep, wide and high with well-placed instruments, most of which were positioned well behind the vocalist. Rhythm and drive were first-rate on the entire disc and well suited to any dyed-in-the-wool rock enthusiast.
The Druids are comparable to the Silverline Sonatina IIs in many ways. The Druids are slightly less expensive, but much more sensitive. Bass power between the speakers was the biggest difference, with the Sonatina IIs having greater low bass. But once the Druids were positioned for best sound, the gap was narrowed, with the edge still going to the Sonatina IIs. The Druids midrange and treble are less reserved than those of the Sonatina IIs. The Druids are more alive and energetic by comparison, and the same holds true for the treble. The Silverlines treble is much more polite and forgiving, where the Druids give a slightly larger helping -- like it or not.
Zu Cable Cables Druid loudspeaker must be judged on its own terms. While there were compromises that needed to be made in order to create the speaker, I judge them wisely chosen given Zu Cables design goals. The Druids dont have much deep bass, but Ive been using subwoofers for years, and I like the added flexibility a sub can add to a system while it reduces the demand low bass makes on the main amplifier. This flexibility also means that one way or another the Druid can be used in just about any room -- another plus.
When you consider the excellent build quality, high sensitivity and remarkable dynamics, both macro and micro, with just a few watts, Zu Cables Druid is worthy of an audition if youre into low-power amps. Further, when you consider that most speakers as frugal with a watt are much larger and often much more expensive than the Druids, the speaker from Zu Cable is again worthy of your consideration.
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