Portable speakers with passive emitter

Passive emitter

— a passive radiator is a device in the form of a speaker cone, behind which there is no coil with a magnet; such a radiator is not a sound source, it follows the vibrations from the main speaker (speakers). By using such additional cones, usually, the sound of the speaker at low frequencies improves; a phase inverter performs a similar function (see the relevant paragraph), but passive radiators are more compact and simpler in design, which positively affects the price and dimensions.