I’m an audiophile and home theatre enthusiast. I keep hearing the term “passive radiator” and when I google it everything just goes over my head. Can someone explain like I’m 5?
In: Technology
One way of making a speaker is to place your driver in a ported box, which basically turns your speaker into a tube with a driver at one end and a hole in the other end.
Depending on how long you make the “tube”, you can change the resonant frequency of the speaker; this is the same as how a trombone gets longer and shorter and this changes the pitch. Changing the length of the tube, and so the resonant frequency of the box can be helpful to, for example, increase the bass response of your speaker.
A passive radiator is a basically a speaker “hack” to do the same thing. In a speaker with a passive radiator, instead of having a hole in the box, we completely seal the box, we then add a springy diaphragm to one part of the box; something that keeps the box air sealed but can still move in and out.
As the pressure inside the box goes up and down from your driver moving back and forth, the pressure will push the passive radiator in and out. By adjusting the properties of the passive radiator, such as it’s mass and how springy the diaphragm is, we can adjust the resonant frequency of our sealed box, which again can be used to change the sound, such as increasing the bass.
Passive radiators are often useful if your trying to keep the size of the box small, but want to boost the bass, as to do this with a ported speaker would need a long “tube” and so would need a big box.
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