Why Kapton-aluminium ribbon construction?
Aluminium is the conductor; Kapton gives the foil the dimensional stability to stay flat and corrugation-true over decades of vibration and heat.
Not every Clarisys ribbon is built the same way. The mid-range and treble ribbons are pure aluminium — a free-standing foil with no substrate of any kind. The bass ribbon is the only section that uses a composite: a pure aluminium foil bonded to a Kapton (polyimide) substrate. Each construction is chosen for the demands of the band it serves.
Mid-range and treble — pure aluminium bipole ribbons
In the mid-range and treble sections the aluminium foil alone is both the conductor and the diaphragm. There is no Kapton, no Mylar, no carrier film and no adhesive. This gives the lowest possible moving mass — measured in milligrams — and the fastest, most direct conversion of electrical energy into motion. Both sections run as a bipole: a second pure-aluminium ribbon on the rear, driven in phase with the front.
Bass — the aluminium-Kapton composite
The bass ribbon is the one section that needs a substrate. Its large radiating area and the deep excursions of low-frequency reproduction demand dimensional stability that a thin foil alone cannot hold over decades. So the bass ribbon bonds the pure aluminium foil to a Kapton (polyimide) substrate:
- thermal stability — continuous use up to ~400 °C, so high-current peaks do not degrade it;
- high dielectric strength — it insulates the aluminium from the magnet poles even under flex;
- outstanding mechanical toughness — it gives the thin aluminium the dimensional stability it needs to remain flat and corrugation-true over thousands of hours of vibration.
Without the Kapton, the thin aluminium of the bass ribbon would sag, wrinkle, or creep under tension and heat, eventually shorting against the magnet poles or changing its electrical characteristics. The aluminium-Kapton composite is what allows the bass ribbon to remain stable and consistent for decades rather than seasons.
Why the split
The mid-range and treble demand the lowest mass and the purest ribbon behaviour — so they get pure aluminium, no substrate, in a bipole configuration. The bass demands stability above all — so it is the only Clarisys ribbon that is a composite.