First Sounds: Stenheim Alumine Two

by Roy Gregory | March 1, 2017

ust as the audio world seems intent on discovering a silver-bullet solution, the one magic ingredient that guarantees results, it seems equally willing to simply dismiss a given material or technology. There are those who can’t listen to silver cables; there are those who won’t entertain metal-dome tweeters; there are those for whom MDF is anathema; and for each and every one of these listeners there’s another who is just as committed to the opposing view. It’s one of the things that makes high-end audio endlessly fascinating -- but it’s also an object lesson in the dangers of determinism.

If the expression, "altogether too much of a good thing" could have been coined to encapsulate the apparently hard-wired tendency of audio designers to over commit, then "the best of both worlds" might just sum up their ultimate goal. It certainly sums up the Stenheim Alumine Two ($14,975/pair), one of the most impressive and surprising small speakers I’ve listened to. At first glance it would be easy to assume that the little Stenheim fits an established sonic mold: strangely familiar proportions, aluminum cabinet, clean lines -- and super-clean sound? Well, no. Representing proof that it’s not what you use but how you use it that matters, the sound of the Alumine Two defies expectations, both in terms of character and scale. Unlike a lot of the competition, this isn’t a little speaker that sounds bigger than it is; it’s a little speaker that does big music convincingly -- and that’s a far better balance of virtues.

Aluminum cabinets get mixed reviews, not least because their biggest (and loudest) advocates brook no dissent. Company’s like Magico and YG Acoustics are far from wallflowers when it comes to proclaiming the superiority of their approach, and their speakers certainly have their fans. They also have their detractors, listeners who point to bleached tonality, constipated dynamics and disjointed sound -- and who also point accusingly at those substantial metal cabinets. But like most things in hi-fi, it really isn’t that simple. Whilst the cabinet certainly has a huge impact on the sound of a speaker, so do the drivers and crossover, with both Magico and YG employing high-tech drivers and complex crossovers, each with their own sonic shortcomings. But there’s more to a cabinet than the material it’s made from. Aluminum is rightly recognized for its stiffness, but that also means it has a tendency to ring. In fact, get it wrong and it rings like a bell. Shaping of the cabinet walls and bracing can help, but the peaks in an aluminum cabinet panel are so pronounced that simple constant chord braces risk spreading the problem rather than dealing with it.

Originally founded by a quartet of ex-Goldmund employees, Stenheim travels a distinct and distinctly individual path. Those familiar proportions derive from the golden ratio used to develop each speaker's dimensions, an approach also used by Goldmund. The Alumine Two’s thin-wall cabinet is beautifully machined from 10mm aluminum sheet, precisely jointed and bolted together and to a 15mm front baffle by a host of machine screws and strategically placed brackets. Having witnessed the removal and then reattachment the baffle on a large Magico (a process that resulted in two broken mallets, which brought new meaning to the phrase "Get a bigger hammer") the ease and precision with which the Alumine Two goes together is both a revelation and a relief. As well as silicon sealant on all of the joints, the individual panels are damped with large multi-layer pads, each consisting of a bituminous layer, an open foam core and an outer impervious layer. The combination of small, carefully shaped walls, solid fixing and critical damping creates a compact, surprisingly dense and beautifully behaved (and beautiful-looking) enclosure.

But what sets the Stenheim speakers apart from so much of the competition is the choice of drivers. In stark contrast to the much-trumpeted high-tech units employed by the likes of Magico and YG, Stenheim pair their precision-crafted cabinets with drive units that are most kindly described as traditional but might as easily be lambasted as plain old-fashioned by those advocates of metal, carbon, ceramic or diamond diaphragms. Yet it’s this mix of modern cabinet materials and long-established driver technologies that makes the Alumine Two so fascinating -- and arguably so successful.

The drivers are cleanly mounted from the rear of the baffle, making for hidden fixings and a clean acoustic transition. High frequencies are handled by a classic 1" fabric-dome tweeter paired with a shallow waveguide machined into the front baffle. The bass-mid driver is from French professional producer PHL, a 5" heavily doped pulp cone built onto a substantial 6 1/2" basket with an equally substantial motor.

The drivers are laced together with a hybrid, low-order crossover that pays considerable attention to component quality as well as attenuating out-of-band output. The final package is neat and attractive, even if its broad base makes it look a little dumpy to start with. At near enough 13" tall, 9" wide, 11" deep and weighing in at 37 1/2 pounds, the Alumine Two might justifiably be described as squat. More importantly, those wide hips, combined with the thin cabinet walls make for a much larger cabinet volume than you might assume given the speaker’s overall size and appearance. That’s a hidden asset that you are going to seriously appreciate once you start listening, reflected in the very healthy 90dB sensitivity for a speaker this size. An easy load, that sensitivity and the low-loss cabinet with its rigid driver mounting and absence of lossy stuffing all suggest that the little Stenheim might well pack a surprising punch.

With any small speaker the real musical issue isn’t so much its bandwidth as the confidence with which it’s delivered. There’s bass and then there’s the sense of bass. That’s where voicing is crucial -- and not just at the bottom end. The easiest way to make a speaker sound bass shy is to give it a sparkly, extended, attention-grabbing top end. The Alumine Two is perhaps the most convincing compact speaker I’ve used, precisely because it avoids the classic pitfalls that plague most such designs.

Cue up the Berglund/BSO performance of the Sibelius First Symphony [Warner Classics 9 73600 2] and prepare to be astonished. It’s not just that this really isn’t small-speaker music; with its massive and sudden dynamic swings, its rich tonality and broad emotional sweep, the Berglund is all about sheer muscle and energy. Yet the little Stenheims defy expectations, not just surviving the experience but embracing it with gusto, delivering the performance with all of its dynamic and emotional range, it’s raw bone and jagged structure. The plaintive opening theme is beautifully delicate and fragile, but it also brings a sense not just of instrumental location but overall acoustic scale and space. The relentless increase in complexity and level as the first movement climbs and fights its way to its mighty closing crescendo is mapped in all its anguished effort, the shifting grip of the contrasting instrumental groups allowing the music to breathe and swell, surge and recoil as it rises to the explosive climax -- and all from a compact two-way. Shut your eyes and it’s hard to believe that such an emphatic musical performance can possibly have emerged from cabinets of such unassuming dimensions. But more than that, that the speakers can achieve such impressive musical communication and poise on the end of a pair of OTL amplifiers. With the quick, lucid but far from muscle-bound Berning Quadrature Z monoblocks doing the driving, the sheer musical enthusiasm, purpose and intent that result are impressive in every sense, both musical and sonic.

So what’s Stenheim's secret? Arguably this is a speaker that trades low-frequency extension for sensitivity, the opposite tendency of so many compact designs. The result might be less bass, but what there is is demonstrably more effective, not least because of the speed with which it arrives and its ability to respond so easily to the subtleties and nuance in the incoming signal. That’s where that larger-than-expected internal volume comes in -- and the massive front-firing port that couples it to the outside world. Crucially, the bottom end reaches down as far as the all-important 50Hz mark, where proper musical underpinnings really start. (Stenheim does offer a pair of passive subwoofer columns to quite literally underpin the Alumine Two, but that’s a whole different product, a whole different price and a whole different set of compromises, leading to a whole different article.) Sacrifice sensitivity and you could push that low-frequency roll-off down quite a bit further, but then you’d end up with another hard-to-drive miniature that sounds too big for its boots.

This is about delivering musical power, and the Alumine Two’s speed of response, the willingness with which it reacts to input, is all-important to its conspicuous success. It’s no surprise that if the Alumine Two reminds me of any other speaker, it’s the Reference 3A de Capo, another squat two-way with a bigger-than-average bass driver and a higher-than-expected sensitivity, but the Alumine Two is in a different league when it comes to detail and refinement, resolution and focus. The Stenheim is remarkably cultured, devoid of rough edges; energetic and enthusiastic it might be, but never at the expense of its musical manners. The lack of dynamic compression in the Bernings is meat and drink to the Alumine Twos, as are their transparency and resolution. Together the amps and speakers are an astonishingly effective pairing: just add signal derived from a high-quality front-end.

As with all speakers, changing amps required a shift in speaker position, especially when swapping between the Gryphon Diablo 300 and the Bernings. The Icon Audio Stereo 60 shared a position closer to that of the Gryphon than the OTLs, but all three amps shared a siting that was quite a bit closer to the wall than expected, without compromising the depth dimension. The other thing they all shared was their easy interaction with the Alumine Two, the speaker feeding off and reflecting the character and the quality of the driving amps. One peculiarity I did note was that the Stenheims opened up significantly, breathing more easily on taller stands. I set the speakers up on Track Audio stands with their modular columns, starting with a height of 24" but actually preferred them slightly higher, adding another 4" insert to bring the top of the speaker up to 41". That aside, the Alumine Two was a joy to use, playing nicely with a whole host of different playmates, never getting grumpy or fractious.

A lot of that musical integrity derived from the carefully executed hybrid crossover and the equally carefully tailored top end. For those used to the latest wunder tweeters, laden with exotic materials and with the sort of claimed extension to worry any passing bats, the Alumine Two’s lowly fabric dome might seem distinctly infra-dig, its top end somewhat dull and shut in, and, in truth, I suspect that in terms of frequency response they might well be right. But if the Alumine Two’s tweeter does roll off a tadge prematurely, in doing so it maintains an almost perfect sense of balance against the bottom end, leaving neither exposed. The result is a musical whole that is significantly greater than the (numerical) sum of its parts -- and is no mistake. Combine that with the speaker’s superb temporal accuracy, seamless integration and even tonality and its spatial, rhythmic and musical coherence start to make sense. In many ways, the Stenheim Alumine Two is living proof that less really can be more -- and that newer isn’t necessarily better.

Turning to music that plays to traditional small-speaker strengths, it’s no surprise to find the Stenheims reveling in the opportunity offered. A Petite Bande recording of Corelli Concerti Grossi [Deutche Harmonia Mundi/Sony Music 88750 37502] has all of the structure and precision you’d expect from these baroque masterpieces, but is also full of the characteristic body, life and energy that inform this orchestra’s work. Lorraine Hunt Lieberson’s performance of Handel Arias [Avie AV0030] has an astonishingly natural vocal quality, her enunciation and articulation making what can be arcane music both immediate and affecting, the range and purity of her mezzo-soprano voice a perfect contrast to the studied poise of the period accompaniment from Harry Bicket and the OAE.

But before you go getting the idea that these speakers are all about polite classical performance (in every sense of that phrase), just play something that’s seriously rude -- at least in recording and production terms. How about the impromptu Alison Krauss/Gillian Welch duet "I’ll Fly Away" from the Down From The Mountain concert [Lost Highway 088 170221-2]? The separation of the voices, the pace and attack of the guitar and mandolin, the chemistry that exists between the performers, all are clearly apparent and, in their own way, point directly to what makes the Alumine Two such an impressive performer: its ability, irrespective of scale or genre, to cut to the core of and communicate the sense and purpose in the performance. It’s the way in which this speaker allows each performer and each performance both to reveal its own voice and to speak for itself that places it in a very select group indeed. To do so from such a small enclosure and at the same time with such convincing dynamics and scale, yet to place such an easy load on the driving amplifier, make the Alumine Two unique, at least in my experience. The Reference 3A treads some way down the same path, but it can’t match the Swiss speaker for refinement, resolution, the natural sense of scale and balance it brings to the music, or fit, finish and appearance.

Sadly, this pair needs to return to the land of chocolate, cheese and cuckoo clocks, but even in a house blessed with way more than its fair share of serious and seriously expensive loudspeakers -- and where hi-fi is hardly space limited -- the Stenheim speakers carved themselves a niche that’s going to be hard to fill. Is this the nearest thing I’ve come to a genuine do-it-all, do-it-anywhere loudspeaker? It might just be. It’s certainly my favorite two-way since the original Wilson Duette started standing with its back against the wall. How much of that easy, rhythmic fluidity and grace under pressure are founded on its sensitivity and the easy load that it presents to the driving amp is an interesting question. Is the Alumine Two a great-sounding speaker or simply one that brings the best out of your amplifier? This really is the definition of a moot point, given that you can only listen to a system, but it’s also significant that I enjoyed a lot of fine-sounding systems with the Alumine Two hanging on the end of them.

If you need a compact speaker that allows your music to breathe, that’s big on expression, big on intimacy and big communication but isn’t phased by big or loud, then the Alumine Two could be just what you’re looking for. Other brands might make more noise about (and with) their aluminum boxes, but right now it’s the Stenheims that are delivering the musical goods.

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