Operation of a passive radiator

The passive radiator (or passive loudspeaker) fits into a box with an active loudspeaker. This passive radiator, although it may at first glance look like a "classic" loudspeaker, in fact has no engine parts. Thus, there is no coil, magnet and power supply in its design. In the same way, it will not be electrically connected to a power amplifier.

To diffuse sound, the passive radiator will use the air pressures and depressions induced by the active loudspeaker in the cabinet to vibrate its diaphragm to deliver deep bass. Its resonance frequency is determined by its mass and the air contained in the cabinet. It is therefore possible to vary its resonance frequency on many models and tune it to the speaker by adding mass.