Its industrial name is Curv®, "a self-reinforced 100% thermoplastic composite made from heat-compacted woven polymer fibres". On the stiffness-to-weight index, Curv scores three times higher than polypropylene and twice as high as polycarbonate. On impact resistance it's ten times better than polypropylene. "In a unique and patented process, highly drawn polypropylene tapes are heat treated to selectively melt every surface. The melted material bonds the tapes together to produce a single polymer composite that enhances the material properties through molecular orientation resulting in self reinforcement.
"This unique structure bridges the performance of isotropic polypropylene and continuous glass-reinforced polypropylene composites". SEAS explain that the material's properties allow their Curv diaphragms to use low-loss surrounds unlike classic polypropylene which required high-loss surrounds. In 2020 Mike Klasco wrote in Voice Coil that the most promising development with poly cones is Propex's Curv which has the benefits of injection moulding and the low tooling cost of compression thermoforming.
"Yet after more than a decade since its introduction, only a few vendors have achieved exceptional results. Curv offers high stiffness, high tensile strength and outstanding impact resistance at low density and half the weight of glass-reinforced materials with higher resistance to temperature extremes. Sophisticated European boutique brands like SEAS and Wilson Benesch have mastered the technique of forming without degrading Curv's molecular grain orientation." Might we call Curv the poorer cousin of spread-tow carbon-fibre? Its key assets for speaker membranes seem to be its combination of strength, lightness and imperviousness to moisture plus cost-effective manufacture. In Wilson Benesch lingo, they refer to their related drivers as various generations of Tactic. That's short for isotactic polypropylene, a material they developed in partnership with physicist professor Ian Ward of Leeds University funded by a government research grant. Whilst their material isn't the Propex Curv formulation and process, according to the earlier Klasco quote it is a similar parallel invention. For another wrinkle on beyond-polypropylene efforts, consider the Harbeth Radial cone and its history.
The above photo is from The-Ear.net's report of the 2025 UK show to stress that the British racing green finery on display there wasn't exclusive to Frida but grows just as readily on Gro.
Gro for groceries? As an abstinent fruitarian, your grocery list will be far narrower than an omnivore's with its meat, fish, fowl, alcohol and vape. Some speakers tune for special diets. Others are what Germans call Hans Dampf, the English Jack of all trades. Hence a Schwalbe all-terrain tyre for mountain bikes goes by Hans Dampf. Germans also have the 08/15 idiom. It can affix to anything shy on individuality or creativity. It says mediocre or simply, ordinary. The expression immortalizes the MG 08/15 as the most common mass-produced German machine gun of WW1 with its tendency to jam. You see the lines. Being excellent at certain things means being less so at others. Otherwise nothing can stand out. That specializes appeal. We don't hire a brain surgeon for a bum knee. Being uniformly good implies that nothing does stand out. It aims lower in the full saying Jack of all trades, master of none. Like Mao's dress code, uniformity also limits individuality. What's best? Complete excellence at the highest level where everything stands tall including distinctive individuality? If we put Gro on our grocery list, is that what we get? To stick to a name theme, Google proposed 332 words beginning with gro. Just 42 of them are common. Let's see which suit this narrative.
SV-Audio's 7-inch version | four of them in Fenja for a compound surface of one 14" woofer for claimed 12Hz reach.
