High-end audio has a long history of manufacturers refining their existing products and then applying the “Mk II” designation. Given that high-end audio designers are perfectionists by nature, it’s understandable that they will revisit a design and try to make it better. Usually, the product’s basic platform stays the same while the implementation and parts quality are upgraded. In my experience, Mk II versions tinker at the margins of a product’s sound, but do not fundamentally change it. The product’s sonic character is still apparent, with perhaps a little more transparency, lower noise, smoother timbre, or other such incremental advances.
The new Mk II version of Magico’s Q7 loudspeaker is not one of these products. Yes, the changes appear to be minor; nonetheless, the Mk II takes the Q7’s sonic character in a new and unexpected direction. The Mk II updates, surprisingly, allow a very different listening experience to unfold.
In my review of the Q7 in the January 2013 issue, I concluded that Magico’s flagship was “the single most impressive product—in any category—in my 23 years of full-time reviewing.” Nothing in the intervening two-and-a-half years has changed that opinion. To recap, the Q7 is a four-way, five-driver dynamic loudspeaker in a sealed enclosure. The drivers are all custom built specifically for the Q7, including the dual 12" woofers, 10" mid/bass driver, 6" midrange, and 1" beryllium dome tweeter. The drivers’ motor structures are extremely sophisticated, and the diaphragms are made from a woven carbon-fiber material called Nano-tec. The enclosure is as heroic as the drivers; the 750-pound speaker is built from solid slabs of aluminum reinforced by an intricate three-axis aluminum bracing. Although the Q7 appears from the outside to be simply a scaled-up Q5, the Q7’s enclosure and driver technology are significantly more sophisticated. (See my review in Issue 229 for the technical details.)
So how can such a tour de force in loudspeaker design be improved? On paper, the Q7 Mk II appears to be a minor update rather than a major overhaul. The “only” differences in the Mk II are a new midrange driver diaphragm, a new tweeter, and a revised crossover. That’s it. The price has increased from $185,000 to $229,000. Q7 owners can upgrade for $44,000, exactly the price difference between the models.
Let’s look at the upgrade in detail. The midrange diaphragm, which had been made from Magico’s carbon-fiber-based Nano-tec material, has been replaced with a different carbon-based material. This new and highly advanced material is 30 percent lighter than Nano-tec, yet is 300 percent stiffer. The combination of lightness and stiffness is the Holy Grail of driver design; the lightness allows the diaphragm to start and stop quickly by virtue of its low mass, and the stiffness prevents the diaphragm from flexing (and thus introducing distortion) under the stress of being driven by a voice coil attached to it near the diaphragm’s center. A light diaphragm can also provide superior low-level resolution; music’s very fine details are not obscured by the diaphragm’s inertia. Think about the very low-level components of an audio signal—the most delicate musical details of timbre, microdynamics, and ambience—applied to two drivers, one of them with a high-mass diaphragm and a stiff surround material, and the second with a featherweight cone and very compliant surround. It’s easy to visualize how, with the high-mass cone, music’s very fine structure would fall below the driver’s ability to move in response to that signal. The driver’s mechanical structures set a threshold below which no information can be resolved. But the lighter the diaphragm, the more powerful and sophisticated the motor structure, and the more carefully designed the surround material and its shape, the lower that threshold becomes. The result is an increase in low-level detail. Moreover, lighter diaphragms more faithfully reproduce the leading-edge attack of transients, which translates to a greater sense of realism and better conveys microdynamic expression.
The new diaphragm’s improved characteristics were made possible by a breakthrough carbon material called graphene. In conventional carbon fiber, the fibers are woven into thin sheets layered atop one another. Resin added to the carbon fiber melts when heated, and then cures when cooled, bonding the layers into a single structure. This resin accounts for most of the weight of a carbon-fiber diaphragm. But graphene isn’t a carbon fiber. Rather, according to Wikipedia, it is “a two-dimensional, atomic-scale hexagonal lattice in which one atom forms each vertex” (see illustration at right). That is, this form of carbon isn’t a fiber or a nanotube, but a lattice structure just one atom thick. Again according to Wikipedia, “Graphene has many extraordinary properties. It is about 200 times stronger than steel by weight, conducts heat and electricity with great efficiency, and is nearly transparent.” Although graphene’s existence was known for decades, it became a commercial product after a series of groundbreaking experiments by Andre Geim and Konstantin Novoselov at the University of Manchester, for which they were awarded the Nobel Prize in Physics in 2010. Magico’s research into new diaphragm materials led them to graphene. When Magico contacted the company making it, the company was surprised to learn that graphene had an application in loudspeaker drivers.
The Mk II’s tweeter is a ground-up design three years in the making. The new dome’s diameter is slightly larger than that of the Q7 (28mm vs. 26mm), and the beryllium dome is now coated with a thin diamond layer. The diamond coating increases the dome’s stiffness, reducing distortion and extending the frequency range over which the dome moves as a perfect piston. Diamond also adds a bit of mass to the dome, but presumably this disadvantage is more than offset by the greater stiffness. The tweeter’s geometry is completely new, including the magnet structure and the chamber behind the dome.