The cones are the drivers that do the heavy lifting — the woofer, mid-bass and midrange that move air to make bass and voices. Their material gets a lot of marketing attention: Kevlar, aluminium, flax, carbon fibre, exotic sandwiches. Some of it is genuine engineering and some is just a colour you can see through the grille.
This guide explains what each common cone material actually does. For the tweeter's diaphragm — a separate world of soft domes, metal, ribbons and AMTs — see the companion guide, Tweeter types explained.
The three things a cone can't all have at once
Every cone material is a compromise between three properties, and no material maxes out all three at the same time:
- Stiffness — a stiff cone stays rigid and moves as one piece (a clean 'piston'), instead of flexing and adding its own sound.
- Lightness — a light cone starts and stops fast and is easier to drive (higher sensitivity).
- Damping — internal damping absorbs vibration, so when the cone does flex, it doesn't ring like a bell.
The key failure mode is breakup: at some frequency the cone stops behaving as a piston and starts resonating, adding a harsh peak. Stiff materials push breakup higher (good) but often ring hard when it finally happens (bad, unless it's damped or filtered out by the crossover). That tension is the whole story of cone materials.
Paper and cellulose — the original, and still great
The first cones were paper, and treated paper (or natural cellulose pulp) is still one of the best all-rounders. It's light and naturally well-damped, which tends to give a warm, musical, easy-to-listen midrange — the reason so many classic and studio designs stick with it. Modern versions coat or blend the pulp to add stiffness and resist humidity.
Dali is perhaps the best-known example of all — it mixes wood fibre into its paper pulp, giving an uneven, low-loss cone that runs through almost its whole range, from the affordable Oberon line up to the Epicon flagships. Triangle uses natural cellulose-pulp midranges across its French-built ranges, and Fyne Audio drives its point-source designs with a multi-fibre cone in the same tradition.
Polypropylene and filled plastics
Polypropylene and mineral-filled plastics are inexpensive, consistent to manufacture and very well-damped, which is why they're common in budget speakers and in a lot of pro/monitor gear. They keep breakup benign and rarely sound harsh; the trade-off is that a plain plastic cone can sound a touch soft or lacking in the last bit of detail compared with a stiffer material.
You'll see them most at entry price points — for example in the powered ConneX models from ELAC.
Metal cones — aluminium and magnesium
Aluminium and magnesium cones are very stiff and light, so they stay pistonic and detailed across their working range and extract fine detail from a recording. The catch is a sharp, high breakup peak: metal doesn't self-damp, so a good design either pushes that resonance above the crossover or uses a precise filter (a 'notch') to kill it. Done well, metal cones are clean and articulate; done badly, they can sound bright or metallic.
Monitor Audio's gold-coloured C-CAM (ceramic-coated aluminium-magnesium) cones are a signature example, and Paradigm uses aluminium (X-PAL) and aluminium-magnesium (AL-MAG) cones through much of its range.
Woven composites — Kevlar, fibreglass and carbon fibre
Woven-fibre cones aim for the stiffness of metal with more built-in damping. Because the weave breaks up in a scattered, gradual way rather than in one sharp resonance, its failure is more benign and less obviously 'ringy'.
- Aramid / Kevlar: stiff and self-damping; the yellow Kevlar cone was a long-running icon of Bowers & Wilkins before its Continuum successor. ELAC uses aramid-fibre cones in its Debut range.
- Fibreglass: a cost-effective stiff/damped balance, used for the woofers in Triangle's floorstanders.
- Carbon fibre: stiffer and lighter again, increasingly common in higher-end woofers — Paradigm's Carbon-X cones are one example.
Sandwich and composite cones
The cleverest way around the stiffness-versus-damping trade-off is a sandwich cone: two thin, stiff outer skins bonded to a light, damped core (a foam or honeycomb). The result can be extremely stiff and well-damped, at the cost of complexity and some added weight. Focal is the best-known practitioner, with its 'W' cone (glass-fibre skins over a foam core) and its flax-sandwich cones that sandwich natural flax fibre between glass layers.
The exotic tip: ceramic, diamond, beryllium
At the top of the market, cones and mid-domes are made from ceramic (hard-anodised aluminium oxide), beryllium or even diamond — materials so stiff that breakup is pushed clean out of the audible band, for near-textbook pistonic behaviour. They're also brittle, unforgiving to manufacture and very expensive, which is why they appear only in flagship designs. The performance is real, but it's the far end of a curve with steeply diminishing returns.
The cone isn't the whole driver
Two parts around the cone matter almost as much and rarely get a mention. The surround — the flexible ring at the cone's edge — is usually rubber (durable and well-damped), sometimes foam (light but it can perish over years) or treated cloth; it controls how far the cone can travel and adds its own damping. Behind the cone, the motor (magnet and voice coil) and a rigid, non-resonant basket determine control and power handling. A modest cone on an excellent motor beats an exotic cone on a cheap one.
So which material should you look for?
None in particular. Cone material sets a tendency — paper leans warm and forgiving, metal leans detailed, composites and sandwiches chase both — but how well it's implemented, the surround, the motor and the crossover matter more than the name of the material. Treat it the way you'd treat a spec: a hint about character, not a score. There's more on this mindset in How to read a speaker spec sheet.
Every TrueScale page lists the driver materials in plain language. Find a character you like the sound of, explore the brands that build it, and line your shortlist up in TrueSpecs to weigh the whole design, not just the cone.