Balanced Armature

Usually used only in in-ear monitors such as Etymotic, Shure, Sensaphonics, and Ultimate Ears. They generally are limited at the extremes of the hearing spectrum (<16 kilohertz, >50 hertz) and require a seal more than other types of drivers to deliver their full potential. Some in-ear monitors, such as the Ultimate Ears super.fi 5EB, combine an armature driver (for high frequencies) and a small dynamic driver (for low frequencies), for the benefit of lower costs. For the higher-end models, such as super.fi 5 Pro and the Shure SE420/E5, two balanced armature drivers were utilized for a more balanced picture. Flagship models such as the Ultimate Ears UE-10, Shure E500/SE530, and Westone ES3 employ three balanced armature drivers with a view to enhance the sound towards perfection. However, multiple-driver earphones tend to have the problems of inaccurate spacing and emphasis in the bass department, thus losing some fidelity. This is compensated by a couple of technologies, such as routing a balanced armature to handle a dedicated range of notes, utilizing a specialized port (or air duct) to allow air to flow through the armature for increased efficiency, and utilizing inline crossovers to ensure accurate reproduction of high, mid, and low notes to rectify these weakness.

Besides the construction of the actual sound producer, the amount of "load" or impedance on the line is an important differentiating factor among headphone design. Many common headphones using a dynamic driver resting on or slightly in the ear have 32 ohms impedance. Smaller, in-the-ear types may have an impedance as low as 16 or 11 ohms. "Studio" and noise-reducing headphones tend to have much higher impedances, ranging from 300 in some cases to as high as 5000 ohms in other.