The optimal core material for inductors is air. For physical reasons, air-core coils are superior to all metal-core inductors in impulse fidelity and freedom from distortion, because no core-related losses, nonlinearities or saturation effects can occur. They can therefore be used in all sections of a crossover: as an inductor in the midrange branch, as a bass inductor with a large conductor cross-section for low resistance, or as an equalization inductor in a correction network with a thinner wire gauge. Especially in high-quality loudspeakers, air-core coils convince with fine detail, precision and dynamics. They thus form the basis for a lifelike, harmonically beautiful music reproduction. The prerequisite is appropriate dimensioning of inductance and DC resistance as well as clean installation, so that the coil can fully realize its potential.