I have the Logitech Z523. The subwoofer has a 4" powered driver with a 6.5" passive radiator. My question is, do passive radiators actually make any "sound" or "noise"?
asked Oct 12 '12 at 14:47
Passive just means that it isn't powered. It's more of a diaphragm that amplifies the bass from the speaker box. It's essentially a speaker with no magnet or driver.
answered Oct 12 '12 at 16:56
Yep the passive diaphragm does produce sound. A more extreme example of the passive design is the subwoofer on the logitech z-640
the z3e also uses this design
here is a video of how it sounds without the passive element http://www.youtube.com/watch?v=h0wkpv5IAYk&feature=related
not very impressive
now with the passive element http://www.youtube.com/watch?v=3h3AAletuiU
To lower the cost, a smaller speaker designed to caused the most change in air pressure is places in a sealed enclosure, then the pressure change then causes the passive element to move. this filters out any higher pitched sounds that sub woofers do not handle well (with out the need of any special electronics), it also makes the sound less focused so it becomes more room filling (a larger diaphragm with less movement fills a room more than a small diaphragm with a lot of movement.
Here is a more in depth look at the passive design http://www.jeff7.com/projects/z-640/index.htm
answered Oct 13 '12 at 12:36