The Stenheim Alumine 5-SX Loudspeaker
By Roy Gregory
Since its arrival, over a decade ago, Stenheim’s Alumine 5 has become something of a benchmark in the market place – and a fixture around these parts. It quickly established a reputation as a versatile and musically engaging performer, one that remained largely unfazed by different partnering equipment and different sized rooms. Equally at home with tubes or solid-state amplification, it grew into large spaces and yet seemed just as happy and enthusiastically entertaining in smaller ones. It’s no surprise that for an increasing number of dealers it has become the ‘go-to’ option, for an increasing number of listeners, the end-game speaker.
On the surface, the reasons seem clear. With its classic, three-way, twin bass driver, large diameter midrange line-up – a format first established (if not first implemented) by the WATT/Puppy, coated silk and paper drivers and machined aluminium cabinet, it would be easy to assume that the A5 sits in the sweet spot between Wilson and Magico designs. Sonically at least, you wouldn’t be far wrong, with the Stenheim’s easy dynamics and musical energy combined with excellent linearity, integration and clarity scoring on both musical and technical grounds. But look closer and things are not that simple. For starters, there’s the whole question of which A5 you are talking about. But beyond that you need to look beneath the skin to appreciate how and why the A5 succeeds. This is a speaker in which the correlation between technical and material execution and the results achieved sees unusually clear – something that becomes even more apparent with the latest iteration and the introduction of the SX base.
Start at the beginning…
But first (for all those who haven’t been paying attention, or who’ve arrived late at the party) a brief primer on the basics. The rather bluff, four-square cabinet of the A5 conceals a number of important and far from trivial factors, all of which have a direct impact on its sonic and musical performance. The critically braced aluminium enclosure allows for thin walls without sacrificing rigidity. That in turn allows for a much greater internal volume than the external dimensions suggest: volume that can be directly translated into bandwidth and/or sensitivity. The difference between a 15mm cabinet wall and a 40mm one might not seem like much, but do the maths…
Keeping things simple, we’ll propose a cabinet with 25 x 50 x 100cm dimensions, giving a total external volume of 125,000cc. With simple 15mm walls, that would offer an internal volume of 100,298cc. With 40mm walls that drops to 65,688cc! That gives the thin-wall cabinet over 50% more internal volume than the thicker-wall alternative, for the same external dimensions – and domestic impact. That’s a serious increase in bottom-end extension or sensitivity – or a bit of both. Throw in a pair of 10” bass drivers and you’ve got a potent recipe.
Stenheim doubles down on the advantages of their thin-wall cabinet design by using low-volume damping materials, rather than stuffing the cabinets with ‘fluff’. Their sophisticated dual-layer damping pads control the mechanical behaviour of the cabinet walls without slowing or over-damping the enclosed air mass. They control THAT with golden ratio cabinet proportions and carefully calculated slot ports, one for each bass driver and asymmetrical internal spaces for each of the drivers. All of which helps explain just how lively and vibrant the Alumine 5s sound. Looking at the numbers, the A5 offers the surprising combination (at least it’s surprising given its external dimensions) of 94dB sensitivity and a 28Hz to 35kHz bandwidth.
