OFC Copper

• Purity: at least 99.995% Cu, often 99.999% (4N) or higher
• Feature: almost oxygen-free (typically <10 ppm)
• Result: more stable grain boundaries, less oxide formation, more uniform electron flow

Polypropylene as the Insulator

The conductor of the coil is a foil made of (Angelique) copper, silver, or (Angelique) silver-gold. Unlike enameled copper wire, for example, the foil is not coated with enamel for insulation; instead, a polypropylene film wound together with the foil conductor serves as the insulator.

Electrical strengths

• Compared to wire enamels, polypropylene has a low dielectric constant and very low dielectric losses → very low parasitic capacitance
• The polypropylene film is thicker than a typical wire enamel coating → further reduced parasitic capacitance
• A foil coil tightly wound with PP film forms an extremely solid block. The softer PP film also provides strong damping against mechanical vibrations.

Massive Metal Foil

Solid metal foil means: A real metal foil forms the electrode — not a wafer-thin coating. This provides very high, uniform conductivity along the coil, reduces field gradients and enables high current carrying capacity. The higher film weight reduces field force-related vibrations and the electrode remains stable even under impulse load. This creates a robust basis for demanding applications that transfers energy directly and in a load-stable manner — without “flickering” on the electrode side.

Tonal effects

• More pressure and control in the bass/root tone, with clearer contours instead of buzzing
• Superior at level peaks: less compression, more headroom and punch without harshness
• Cleaner transients and more stable dynamics, even with fast pulse trains
• Quieter, more ordered sound: less flicker/internal discolouration, better audibility in complex passages

Air coils

Air coils are the uncompromising reference: maximally linear, without distortions caused by the core. They deliver maximum impulse fidelity and particularly natural, open playback. If space and a sufficiently low DC resistance are possible, air is the first choice.