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Equipment Review

July 2001

Diapason Nux Loudspeakers

by Bill Cowen


Review Summary
Sound "On the warm side of neutral," but not "slow, syrupy or rolled off" -- more "an expression of forgiveness and an absence of forced detail and treble etch"; "in the soundstaging and imaging departments, the Nux was more like a good minimonitor than a floorstander"; "what the Nux is ultimately all about: reproducing music, not hi-fi."
Features "The front baffle is solid walnut, and the remaining 'walls' consist of seven plies of real-wood veneers bonded together"; the crossover "consists of a single high-quality capacitor," and "the woofer is designed to operate full range."
Use Despite the quoted 89.5dB sensitivity and 8-ohm load, Bill found the that the Nux needed 50Wpc to come alive.
Value Bill hasn't "heard a speaker in this price range that does so many things so well, and one that deals with the limitations imposed by cost so effectively."

I don’t understand Italians. Everything they do -- from making cars to buildings to clothing and, yes, even to audio equipment -- is done with such elegance and style. Have you ever seen a Ferrari shaped like a Ford Taurus? Ever seen an Italian woman dressed in polyester, complete with a few snags to complete the look? Ever seen an Italian loudspeaker covered from top to bottom with a black sock? Me neither.

Enter the Diapason Nux, a loudspeaker so very Italian with its gorgeous cosmetics, and so very Italian in its keen attention to style and detail. Maybe it’s Americans I don’t understand.


The $2499 USD Nux loudspeaker is the product of Sound Center Diapason and was designed by Alessandro Schiavi. Lest you think that the gorgeous walnut exterior was meant to hide something, understand that there is as much under the skin as there is on it. With a rated sensitivity of 89.5dB and a nominal impedance of 8 ohms, the two-way Nux should be a relatively easy load for most any amplifier.

The cabinet is unconventional in that it’s not made from traditional speaker materials -- no MDF, concrete, or polymer. The front baffle is solid walnut, and the remaining "walls" consist of seven plies of real-wood veneers bonded together, with the grain orientation of each layer laid opposite to the next. These layers are then heated and formed to produce the desired shape, resulting in a multi-angled cabinet without any parallel surfaces. The rounded back was designed for best sonics, and Schiavi even went through three different cabinet manufacturers before he was satisfied with the quality of the construction. Carrying on in unconventional mode is the lack of any insulation (or "stuffing") inside the speaker. Nothing there but air. A curved tube is utilized internally, culminating in a rear-firing port. The tweeter is a 21mm-diameter isodynamic design, specially built for Diapason, and the bass driver a 165mm polymetylpentene-coned unit. Both drivers are matched between stereo-pair cabinets to a 1% tolerance. Specified frequency response is 40Hz-20 kHz.

Moving on to the crossover, there’s not much to describe -- it consists of a single high-quality capacitor. This cap acts as a high-pass filter for the tweeter, while the woofer is designed to operate full range. Huh? To quote the owner’s manual: "In more than 10 years of advanced research and design, Diapason has developed the system known as Direct Drive, which allows a direct connection between the amplifier and bass driver, thereby eliminating the disadvantages of a low-pass filter, such as loss [of] efficiency and phase rotation." Sounds logical, but the final sonic result is all that matters to these ears.

The binding posts are set into the bottom of the speaker, which helps to maintain a full 360-degree exterior finish. With heavy, bulky speakers, bottom-mounted binding posts are only fit for back-pain-obsessive masochists. With the Nux, they proved to be no problem due to the ease of moving and lifting the cabinets. An oblong cutout exists in the back of the base, which allows ample room for even reasonably thick speaker cables to exit without interference. The review pair of speakers was configured for biwiring, but according to Alan Kafton, Diapason’s US distributor, currently manufactured units come standard with a single pair of binding posts. Biwire capability is still available, but only on special order. Spikes are included for coupling to the floor, although it was a bit difficult to get the speaker to settle down through my thick carpet, due mostly to the minimal weight of the speakers.

Finally, the review pair was finished in the standard real walnut. Custom automotive finishes are also available at extra cost and include a deep anthracite metalflake and BMW silver metalflake. Even more colors are available by special order. I saw the deep anthracite finish at the last CES, and it was simply stunning. The walnut provides a more traditional appearance, while the custom finishes can turn this speaker into an objet d’art.


The Nux is a refreshing change of pace from the usual behemoths that dominate the audiophile speaker range. No hernias, no slipping the neighbor’s kid a $20 to help schlep them around, and no complaints from the significant other about them obliterating and/or dominating the décor. Even better, placement is not a finicky, irritating ritual. They won’t work best right up against the wall, but neither do they need to sit out in the middle of the room like a highway barricade.

I found the best balance in my 17'6" x 25'6" room with the speakers 38" from the rear wall, 51" in from the side walls, and just slightly toed-in. But note that this position was what worked best in my room, so feel free to experiment on your own. Rooms are as different as the speakers that occupy them.

The Nuxes (Nuxii?) spent time powered by a number of different tube amplifiers: the Wavac MD-300B (10Wpc SET), an Audio Electronics AE-25 Super Amp (15Wpc push-pull), a Cary V-12 (50Wpc push-pull) and the Cary 805Cs (50Wpc SET). Despite the speakers' sensitivity rating, I didn’t feel that they came to life with either of the lower-powered amplifiers. They would play moderately loud, but they were lacking some of the bass slam and drive that I found them to be quite capable of providing. A low-powered solid-state amplifier may produce entirely different results, but I had none on hand to try.

Things changed considerably, however, with either of the 50-watters. The Nux just jumped up and danced, and the listening notes below derive from listening with one of the two 50-watt amps listed above. If you’re considering the Nux with a low-powered tube amp, be sure to give the combo a try before you buy. If you have 50 watts or more of tube or solid-state juice available, you’ll have all you need to get the best that the Nux has to offer.


As Alan Kafton had done the ultimate reviewer-dude favor of breaking-in the speakers prior to shipping them, I plopped them into place, and after some initial placement experimentation, fired up the 45 RPM LP of Frankie Goes to Hollywood’s "Relax" from the disc of the same title [Island 601096-213]. This recording can give the dual 10" woofers of the $9000 Coincident Total Eclipses a run for the money, so I figured I’d see if the Nux could really rock, or merely provide a reasonable facsimile thereof. I was unable to crack any sheetrock, but considering the size of the speaker's single woofer, I was most pleased with the bass output -- clean, clear, nicely defined, totally absent of boom, slop, or mud, and possessing a very nice rhythmic quality. While falling a tad short on the Richter scale when compared to larger speakers with larger woofers, the bass displayed adequate weight and bloom. This recording provided a nice glimpse into what the Nux is ultimately all about: reproducing music, not hi-fi.

Associated Equipment

Loudspeakers – Coincident Speaker Technology Total Eclipse, Köchel K200.

Amplifiers – Audio Electronic Supply AE-25 Super Amp, Cary Audio Design 805C monoblocks, Cary Audio Design 280SE "V-12."

Preamplifiers – Cary Audio Design SLP-98.

Phono stages – Cary Audio Design PH-301 Mk 2, Audio Electronic Supply PH-1.

Digital – Electrocompaniet EMC-1.

Analog – Eurokit Premiere turntable, Graham 2.0 tonearm, Benz-Micro MC-SCHEU and Dynavector Te Kaitora cartridges, Greater Ranges Neuance isolation shelf.

Interconnects and speaker cables – Coincident Speaker Technology interconnects and speaker cables, Coincident and Cardas Golden Cross phono cable.

Power conditioners and power cords – Shunyata Research Hydra power-distribution center, Shunyata Research PowerSnakes King Cobra and Black Mamba power cords.

Accessories – Black Diamond Racing cones and Round Things, Michael Green Designs Pressure Zone Controllers, SolidSteel rack, home-brew sandboxes, Silent Running Audio amp stands (custom for the 805Cs), ASC Half Rounds and Tower Traps, Marigo Audio Labs VTS tuning dots.

Tonally, the Nux falls on the warm side of neutral. Don’t confuse "warm" with slow, syrupy or rolled off, but more as an expression of forgiveness and an absence of forced detail and treble etch. Gunter Wand's interpretation of Bruckner’s Symphony No.9 [EMI 60365-2-RC] provides a good example. String tone was quite realistic, with a nice reproduction of the bow sliding across the strings, but without any screechiness or aggression. Brass had the right bite, but didn’t bite my head off. Kettle drums had proper tone, good impact, and while not breaking the mold with transient speed, they were quick enough to be convincing. Again, rhythmic drive was excellent (and good enough to be worth mentioning again), as I found my foot subconsciously keeping time to the music.

In the soundstaging and imaging departments, the Nux was more like a good minimonitor than a floorstander. Depth was very good, width was wall-to-wall, and layering was good, if not excellent. On Billy Vera’s "Someone Will School You, Someone Will Cool You," from This Ones For You [LP, Rhino RNLP70858], the piano was slightly left of center, and Vera’s vocals were right there along with it, but just to the rear. It was pretty easy to visualize the location of each performer and instrument, with adequate space and air around each. While not particularly evincing of the term "3D," the presentation was very nice and certainly outstanding for a speaker at this price level.

On Joan Armatrading’s "Always" (Hearts and Flowers [A&M 75021 5298 2]), the vocal rendition was spot on. The intimacy and delicacy of this particular song were goosebump-inducing as portrayed by the Nux. "Sweet, articulate, and believable" were the notes I scribbled down while listening. In fact, across many different recordings, the Nux was always quite adept at the vocal thing. On some recordings, I noted a slight chestiness to male voice that does not come through on my Coincident speakers. I’d have to label this as a coloration with the Nux, but it’s very slight in nature and does not get in the way of the music.

Finally, the Nux does not lay bare every sniffle, wheeze, and chair creak from the recording venue, but neither are they muffled or indistinct. The detail and transparency levels, while not scaling the heights of pricier designs, were quite natural -- you hear the notes, the music and the artists, not the extraneous, amusical artifacts. Resolution is a double-edged sword, and if you consider the compatibly priced ancillary components that are likely to be mated with the Nux, the balance between resolution and forgiveness would seem to be about perfect. Personally, I haven’t heard a speaker in this price range that does so many things so well, and one that deals with the limitations imposed by cost so effectively. There’s no free lunch in the speaker world, although with the Nux, you just might get some free dessert.


On hand at the time the Nux arrived were the Köchel K200s, reviewed here previously. The Köchels are nearly twice the price of the Nux and a horn-loaded design with the associated increase in sensitivity. As I noted in the Köchel review, it would be difficult to find two more different-sounding loudspeakers. The Nux is warmer balanced tonally, and provides a more relaxed, more intimate presentation. The Köchels are more vivid, lay out more detail, and are on the more lively side of the tonal palette. While the Köchels were supremely enjoyable speakers with tube amplification, I would recommend a thorough audition if a solid-state amplifier was the intended driving force. With the Nux, although I didn’t have any decent solid-state amps around to try, I can clearly envision enjoyable sonics with even inexpensive (but competent) solid-state amps. Don’t fret -- I’m not throwing rocks at the solid-state amp brigade here, only noting that some speakers have voicing that lends itself better to tubes and some others to solid-state. The Nux could do quite well with both.

Dynamically, the Köchels had the slight edge, both in the micro and macro sense, although I got a little more resolution and definition in the bass through the Nux. Both speakers were similar as far as bass extension, and both had enough weight and bloom that a subwoofer could be used, but would not be a necessity for anything other than pipe-organ recitals and Béla Fleck hippo escapades. In all, the Köchels provided more of a glimpse into the recording, while the Nux provided more of a glimpse into the music itself. As always, your taste and desires will dictate which speaker best satiates your musical craving.


The Diapason Nux was an absolute pleasure to listen to. While not plumbing the depths in the bass or bringing out the crystalline transparency of far more expensive speakers, it produced music on an entirely enjoyable level. Free of obvious colorations that plague many speakers at this end of the price spectrum, the Nux rewarded with many, many hours of freedom from audio-neurosis. If you’re an audio compulsive looking for the most piercing, analytical and expose-every-recording-flaw kind of speaker to be found, sail right on past the Nux (and be sure your wallet is commensurately thicker as well). If you’re searching for a speaker that looks better than most of your furniture, brings across the true musical nature of what’s on the recording and provides purely enjoyable listening, then hook up the Nux and take a long vacation from the audio rat race.

...Bill Cowen

Diapason Nux Loudspeakers
$2499 USD in walnut finish, $2799 in metallic finishes.
Warranty: Five years parts and labor.

Sound Center Diapason
Via delle Tofane, 15
25128 Brescia, Italy

Website: www.diapason-italia.com

US distributor:
audio excellence az
940 East Cavalier Drive
Phoenix, AZ 85014-1912
Phone: (602) 277-0799
Fax: (602) 212-9600

E-mail: alan@audioexcellenceaz.com
Website: www.audioexcellenceaz.com

audio excellence az responds:

Firstly, many thanks to Bill Cowen for a thorough and carefully written review. Without a doubt, he captured all the sonic and aesthetic attributes of the Nux. For those who are questioning the derivation of the name, there is a simple answer. Alessandro Schiavi has chosen an ancient Greek word, as he has done with other Diapason loudspeakers. Nux is ancient Greek for "night."

Some comments regarding the stated bass frequency response of 40Hz. The original prototype was measured at 34Hz-20kHz, but Alessandro, being his careful and conservative self, reduced the stated bass response, so the 40Hz number would be "more accurate for most rooms." He is loath to overstate performance as some manufacturers are fond of doing. Realistically, the Nux plays cleanly into the low 30s. We were achieving 32Hz in our room at CES, which was one of the features that originally impressed Bill Cowen. Of course, each room acoustic will vary.

Regarding the very low-powered amplifiers used in the review, 10 and 15 watts IS a bit low for the best mating with the Nux. However, the amplifier with which Bill first heard the Nux was the EAR V20 -- 24 watts of 12AX7 power. A lovely match indeed. Additionally, the Nux, like all Diapason models, seems to "love" solid-state amplification as well as its "glass bottle" brethren. Bill didn't have the opportunity to experience this, but there is no question that the Nux will "rock" with solid-state designs.

All in all, a superb review. Absolutely no nits to pick. Thank you, again, to Bill Cowen and the SoundStage! crew.

Alan M. Kafton
audio excellence az

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