What's as rigid as Kevlar, as stiff as carbon fibre, light, self-damping and yet easy to use in automated manufacturing?

Whatever it is, it sounds like an ideal material for the manufacture of loudspeaker drivers – and for French company Focal, the solution to finding a new material for forthcoming mid-range speakers was in a traditional industry.

Focal's new drive units, to be used in car speakers rolling out today, and future domestic speaker designs, use one of the most famous of French materials: flax.

France is Europe's main supplier of flax, and its fibres – grown in Flanders, Picardy and Normandy – are used to make top-quality linen fabric prized by the clothing industry worldwide.

For Focal, which had been working for ten years to develop a high-quality drive unit to slot between its Polyglass drivers and the expensive 'W' sandwich cones it uses in its high-end speakers, flax has provided the solution it has long been seeking, giving low mass, rigidity and self-damping properties.

That it's also from a sustainable source appeals to ecological demands – and I get the impression that being a celebrated French material also boosted the attraction for the company, which prides itself in still building its speakers, and the drivers they use, in its factories in France.

During a recent visit to Focal in Saint-Etienne, I was introduced to the company's new material, discovered the reasons for its adoption, saw drive-units being manufactured, and had a first chance to listen to the new speakers using the new flax drivers.

Focal explains that it wanted to improve on the performance of the Polyglass drivers it's been using – and improving – since 1985, and bring them closer to the 'W' drivers, so-called because they use a sandwich of two layers of glass fibre with a foam core. 'V' stands for 'verre' – 'glass' in French, and 'W' in French is of course 'double-V'.

Trouble is, the 'double-V' drivers are expensive to make, because their cones can still only be assembled by hand, as was demonstrated to in the Saint-Etienne factory, where I watched painstaking stretching and smoothing of fibre-glass over formers.

Now Focal isn't averse to doing things the hard way: the company has a clean-room facility where an employee in a 'space suit' supervises the moulding and cutting of Beryllium domes for tweeters – the material is ultra-light and extremely, but can be highly toxic when being worked.

However, the flax material enables the kind of mass-production of larger drive-units required to make affordable high-performance speakers.

Flax/fibreglass sandwich
The new drivers use 0.4mm fibreglass layers sandwiching a 0.4mm woven flax core, and by varying the density of the layers different characteristics can be imparted. In woofers, for maximum stiffness, the fibreglass layers are of a 100g/sq.m material, and the flax 250g/sq.m; for midrange drivers, requiring lightness and maximum damping, 50g/sq.m fibreglass sandwiches a 150g/sq.m flax core.

There'll be no mistaking the drivers, as they have an unusual 'woven fabric' look to them, in a 'natural linen' colour – mainly because they're basically woven natural linen!

It'll be interesting to hear how they perform in home speakers, although the initial signs were positive given the brief listen we had in one of the Saint-Etienne listening rooms.

What was absolutely clear was that, unlike the precision manipulation of delicate materials required to make the W drivers used in the company's Utopia range, the Flax drivers are simpler and faster to put together. At the time of my visit a month or so back the company already had its first production-line up and running making them, with capacity to increase production very quickly, and space to install more lines, as demand requires.

That simpler, faster production process also makes the Flax drivers much less expensive than the W cones (which will continue in the company's flagship models). Whereas W drivers are almost for five times as expensive as the Polyglass units in Focal's entry-level speakers, the flax-based technology just about halves that price differential, while still delivering mechanical and acoustic properties closer to the high-end drivers than the basic models.

Watching the driver cones being made, and then assembled into chassis, connected up and tested – and let's face it, there aren't many speaker companies where you still see that happening alongside cabinet construction, assembly and finishing these days – it was clear Focal has great expectations of its new Flax drivers.

In-house, from start to finish
In common with other models in the company's range, the in-house design and manufacture of these new drive units is critical to the whole speaker production process: by making specific drivers tailored for each model in the range, knowing their characteristics and being able to control the tolerances to which they're assembled, Focal is able to simplify its crossover designs.

That's at odds with many other speaker companies reliant on bought-in drive units, and thus forced to design electronics to make those drivers work in their chosen enclosures. In Focal's view, that really is making life difficult for yourself.

Focal's Flax car speakers are now on sale, with the first home speakers using the technology expected next month: there'll be more on the designs using this new twist on an ancient textile technology as soon as information is available…

Written by Andrew Everard