Passive radiator


Were passive radiators an ultimate failure? Does any speaker company still use them? A friend of mine is asking about them in regard to vintage speakers, and all I remember is being unimpressed. But I don't want to tell him that without some back-up.
arnettpartners
It's a speaker with all the components removed including the
magnet. It is used to replace a port.
The correct way to design a passive radiator, is to run the
Thiele/Small parameters of the woofer and cabinet internal
volume, for a ported/bass reflex(ie:Fourth Order) alignment,
using the diameter of the radiator as, "port diameter." .
Then adjust the weight/mass of the passive radiator's cone, to
match the mass of the air that would have occupied the
resultant port's volume. A passive radiator should always be
1.5 to 2 times the diameter of the woofer.
The cabinet should be sealed, to avoid noise and messing up the alignment. It will, however, operate as a bass reflex system. "Sealed enclosure" indicates an Acoustic Suspension system.