Considerations in high-fidelity moving-coil earphone design

The theory of simple moving-coil earphone behavior is briefly described. Some considerations concerning the measurement of sound pressure response and harmonic distortion are mentioned, with special reference to difficulties encountered at high frequencies. Several design objectives are presented, followed by a discussion of design techniques including two new approaches: 1) the introduction of a damping grease into the air gap of the magnetic structure for increased power handling ability, smoother sound pressure response and improved transient performance near the fundamental resonance; 2) a resonant back-loading cavity for improved low-frequency performance when air leaks are present.