Simple Explanation

A diaphragm or cone that looks like a woofer but doesn’t have a motor. It helps reinforce the bass output of a speaker by responding to air pressure.

Concise Technical Definition

A diaphragm or cone that operates like a woofer but without a motor. It is used to reinforce the bass response of a speaker and is acoustically similar to a port, but it functions as a 5th order device.

Layman-Friendly Analogy

Think of it like a balloon that moves in and out to help push more air—similar to a woofer, but without the electrical power. It helps make the bass sound deeper and more pronounced.

Industry Usage Summary

Passive radiators are used in speaker designs to enhance bass response without the need for a port. They are particularly useful in compact speaker systems where a port might be difficult to implement. By moving in response to the air pressure created by the active driver, they allow the system to achieve deeper bass without increasing the size of the enclosure.

Engineering Shortcut

A diaphragm or cone without a motor that reinforces bass output in a speaker system.

Full Technical Explanation

A passive radiator is a diaphragm or cone that behaves similarly to a woofer but lacks an attached motor or voice coil. It works by responding to the air pressure changes created by the active woofer in the speaker system. This action helps reinforce the bass response, making the system sound deeper. Unlike a port, which allows air to pass in and out of the enclosure, the passive radiator moves in response to the pressure variations inside the cabinet. It is classified as a 5th order device, meaning its performance is characterized by a specific combination of frequency response and damping characteristics that are different from simpler devices like ports or vents. Passive radiators are particularly useful in compact speaker designs where traditional ports might be impractical.