A Primer on our Materials Science

Outside of our unique DSP correction, perhaps the most innovative aspect of our loudspeaker designs is our cutting edge materials science deployment. Three areas stand out in particular.

Let’s begin with our cabinets themselves, which are made from a high performance engineered wood composite called Valchromat. The first duty of any loudspeaker cabinet, but especially a sealed cabinet that has to stand up to the back pressure of a high output subwoofer like ours, is to be acoustically inert. What we mean by this is essentially that it should vibrate, flex and move as little as possible – only the driver should move in a loudspeaker. Cabinet vibrations at best destructively couple with the output of the drivers themselves, contributing to vagueness and muddiness, especially in the low end, and at worse can create audible rattling or resonances.

Broadly speaking, there are three ways to make a cabinet dead. The first is to make it so massive that the acoustic force of driver’s pressure wave is functionally negligible relative to the sheer weight of the cabinet itself. The second is to make it extremely stiff, by selecting rigid materials and by adding internal bracing to the cabinets, making it difficult for them to ripple and vibrate. The third is to dampen any vibrations that do couple to the panels – traditionally the best way to achieve this was through a method called constrained layer damping, wherein a limp, shock absorbing material like rubber is sandwiched in between two rigid layers, like plywood, causing coupled vibration to be dissipated as heat into the constrained layer.

Valchromat gives us all three of these attributes in a single material that can still be precisely machined and joined, allowing us to maintain an acoustically optimal shape and an airtight, void free cabinet with no metal joinery (which can vibrate and loosen over time). It is significantly denser than traditional MDF or plywood, far stiffer than standard MDF or composites, and perhaps most uniquely, highly intrinsically damped due to its construction method. As deployed in our cabinets, with 30mm thick front and side panels and extensive internal cross-bracing, it makes for an extremely dead, extremely high performance cabinet, even at high volumes.

Next, let’s look at our midrange diaphragm material, a thin-ply, woven carbon fiber material called Textreme. A driver diaphragm shares two of the three needs of a cabinet, namely to be both stiff and well damped. Conversely, however, a diaphragm should be as light as possible, in part because the heavier the diaphragm, the less efficient the driver and the more energy must be wasted to move it, and in part because stiffness to weight ratio is the primary determining factor of the highest frequency a given diaphragm of a given diameter can reproduce linearly before it begins to breakup into rocking and distortion modes. When a driver does begin to breakup, as all pistonic drivers eventually will, a high degree of damping ensures that the breakup is well controlled, and does not continue to ring indefinitely or intermodulate distortion products back down into the linear range.

Textreme first and foremost exhibits a superb stiffness to weight ratio. Because of its unique construction, it can be formed into a wide range of geometries, making it perfect for our midranges which must be shaped precisely to form an ideal waveguide for our tweeters. Perhaps most beneficial for our midrange, which must be 6.5” in diameter to optimally load our tweeter radiation, its fiber orientation and direction can be adjusted and optimized to any given geometry to reinforce the cone where it’s weakest, and to localize and distribute rocking modes to much smaller, individual nodes rather than the much larger, uniaxial peak that more traditional materials exhibit during breakup. The 4 triangular patches you see at the corners of the diaphragm represent this optimization in our deployment. As a result, our midrange remains a perfect piston to 9khz, over two octaves past its in use range, and shows a very well controlled breakup thereafter.

Finally, there’s our tweeter diaphragm material, GrapheneQ™, a revolutionary new graphene-oxide matrix developed specifically for acoustic applications, which our loudspeakers are the first ever to deploy. The tweeter diaphragm in any loudspeaker is rather much like the anchor of a relay race. A subwoofer or midrange driver can be crossed over before it begins to exhibit non-linear behavior and breakup, but an ideal tweeter must both remain linear throughout the remaining range of human hearing and show an extremely well damped breakup, as any ringing or distortion modes that occur before Nyquist will still be reproduced. Traditionally one could select a well damped diaphragm material, like a treated textile or silk, that would breakup within the audible hearing range but that would control this breakup well, or a very rigid material, like an engineering metal that can remain pistonic to past 20khz, but that shows an aggressive, uncontrolled breakup when it does. Hence an engineer historically would have to choose between a smooth, non-fatiguing response or a high degree of resolution and detail, but could not have both. Innovations such as ribbons and air motion tweeters addressed this to some degree, but came with their own drawbacks such as extremely narrow sweet spots and dispersion patterns.

GrapheneQ™ shatters this binary. It exhibits a better stiffness to weight ratio than titanium, yet remains as well damped as a paper or textile dome. In our tweeter geometries it remains perfectly linear to 30khz, and its breakup peak is so small, well localized and well controlled that it can be entirely suppressed in our DSP. Importantly, the tweeter response simply falls off after breakup instead of continuing to ring, such that no harsh IMD product finds its way into the audible range. GrapheneQ™ allows us to deploy a tweeter that’s optimally shaped for dispersion pattern, granting a super wide sweet spot in combination with our midrange waveguides without incurring any of the drawbacks of an FEA optimized dome in terms of frequency extension or distortion.