Operation of a passive radiator

The passive radiator (or passive loudspeaker) fits into a box with an active loudspeaker. This passive radiator, while at first glance it may look like a "classic" loudspeaker, does not actually have any engine parts. Thus, there will be no coil, magnet or power supply in its design. Similarly, 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 body to vibrate its membrane and produce a sound, thus providing deep bass. Its resonance frequency is determined by its mass and the air contained in the enclosure. It will therefore be possible to vary its resonance frequency on many models and tune it to the speaker by adding or removing mass.