ShtormStone — the material
The front of a Ref. K is cast from ShtormStone — a granite-and-quartz composite we developed because nothing we could buy was good enough. This page is the long answer to a short question: why would anyone go to this much trouble for a loudspeaker baffle?
Start with the physics ↓ ← Back to the Ref. K01What density buys
A loudspeaker driver is a reciprocating machine. Several hundred times a second it throws its moving mass forward and hauls it back, and every stroke pushes on the panel it is bolted to. If that panel moves — flexes, shudders, rings — it becomes a loudspeaker of its own, playing a smeared copy of the music on top of the music. You hear it as thickness, as glare, as a cabinet sound that never quite leaves.
There are three defences, and you need all of them at once. Mass, so the panel barely accelerates when pushed. Stiffness, so it cannot bend between the fixings. Damping, so whatever energy does get in is turned to heat instead of ringing on. Wood and MDF offer damping, but neither mass nor real stiffness. Metal is stiff — which is why bells are made of it. Solid stone slabs ring too — ask anyone who has tapped a granite worktop.
A particle composite is the way through: stone locked, grain by grain, into a polymer network. Dense like stone, stiff like stone, and every grain boundary scatters and dissipates vibration on its way through. It is the same reasoning that puts granite-epoxy beds under precision machine tools, where a micron of flex ruins the work. At roughly three times the density of MDF, ShtormStone simply refuses to be shaken — there are eighteen kilograms of it around the midrange alone.
“A driver is only as precise as the thing it pushes against.”
The whole brief, in one sentence02Our own mix
Engineered stone is an industry — for kitchens. Every commercial blend on earth is optimised for scratch resistance, stain resistance and how it photographs in a showroom. The one trade that optimises stone for damping casts machine beds, bolts them down out of sight, and never has to listen to the result. Nobody makes such a stone to be seen — and nobody makes it to be heard.
So ShtormStone is not bought. It is made, by us, batch by batch. We buy raw granite and quartz aggregate, resins and mineral modifiers from suppliers who have no idea what we do with them, and combine them to targets that matter for sound and for nothing else: density, stiffness and internal damping, in that order of difficulty. No one makes this material for us, and no one else has it.
03Preparation
Crushed stone arrives dirty in every way that matters. Rock flour, traces of clay, films you cannot see — all of it sitting on the surface of every grain, exactly where the resin is supposed to bond. Cast it as delivered and the epoxy grips dust instead of granite: the material comes out weaker, duller in the wrong way, and different from batch to batch.
So the aggregate is washed. Then it is decanted — settled out in water and poured off, the slow way, until the fines and the floaters are gone and only clean, sharp stone remains. Then it is dried, completely, because epoxy tolerates moisture at the bond line about as well as a camera tolerates sand. It is unglamorous work, all of it done before a single gram of resin is involved. It is also why the finished composite behaves like one solid object instead of an aggregate of compromises.
Every grain rinsed free of rock flour and the films that would come between stone and resin.
Settled in water and poured off, again and again, until only sharp, clean aggregate is left.
Dried right through, so there is no moisture left at the bond line to sabotage the chemistry.
04Interface chemistry
Even perfectly clean mineral gives epoxy only a mechanical grip — resin keyed into microscopic roughness. Good enough for a worktop. Not good enough here.
So the aggregate is treated with silane coupling agents: molecules with two different ends. One end bonds chemically to the mineral surface; the other cross-links into the epoxy as it cures. The result is a continuous molecular bridge from stone to polymer — the same chemistry that keeps dental composites in teeth and glass-fibre composites in one piece. Each grain stops being filler in plastic and becomes structure. Strength goes up, micro-voids go down, and grain ten thousand damps exactly like grain one.
05The matrix
Between the visible chips, the epoxy itself is engineered. Wollastonite — a mineral that crystallises as fine needles — laces through the matrix like reinforcement bar at the scale of a human hair, stiffening it in every direction and stopping micro-cracks before they start. Fine silica powders pack the spaces between the larger grains, pushing density up and leaving less unfilled resin free to flex.
Those are two of the modifiers, and the only two we will name. The rest of the list — and every proportion, particle gradation, mixing order and cure window — stays ours. A formula is not an ingredient list. It is ratios and process, and those stay home.
06The cast
Every face is cast in one piece, in a mould taken from a hand-polished master — baffle, waveguide, port flares and driver recesses together, so there is not a joint anywhere in the load path. The casting then cures for days, unhurried, because a slow cure is a low-stress cure, and a low-stress panel stays flat.
Only then is the face ground back, wet, until the granite shows through — every chip cut to a flat, polished section — and sealed in clear polyurethane. What happens between the mixer and the mould — the order, the temperatures, the times — is the part we keep. Twenty-five kilograms of stone, and not one shortcut in it.
Aggregate, modifiers and resin, weighed out batch by batch — in proportions that are nobody's business but ours.
One pour, one piece: waveguide, port flares and recesses, with no joints in the load path.
Days, not hours. A slow cure carries no locked-in stress, and the panel stays flat.
Ground back wet to a true terrazzo polish, sealed in clear polyurethane, inspected, and only then trusted with drivers.
07The honest comparison
Most loudspeakers at most prices are built the same way: sheet material, a router, holes, veneer. A competent shop can make that baffle in an afternoon, and for most speakers it is honestly fine. That is the problem. We were not trying to build a speaker that is honestly fine.
Our way takes washed and decanted stone, silane chemistry, a cure measured in days and a long wet grind — per face. Nobody needs a mechanical watch; the phone beside it keeps better time, and people pay for the watch anyway, because what they are buying is the engineering — the thousand decisions resolved in a small space. The Ref. K asks to be understood the same way, with one difference. Here, the craftsmanship is not only something you own. It is something you hear.
“We did not set out to make a stone. We set out to make silence for the drivers to work against — and had to invent the stone to get it.”
Request an auditionOne hundred pairs a year, each pair numbered. Auditions by appointment — John Dougan, +7 903 220 0175