Passive Radiators

[KillaCam]

So I know what they are and what they do but I wanna know the advantages/disadvantages, the type of situations to use them in. All that jazz.

Also if you have a passive radiator setup how does it sound? Or if you prefer it over a port.

I never heard of them until I saw Steve put them in his towers, so I just want to know more about them.

[bigkevy]

i second that. they look pretty cool

[Superjay]

unless you have LOTS of experience with design (and know how to read specs and what they all mean, and what happens when you change them) I'd avoid passive radiator applications.

[bumpinTL364]

+1, it essentially acts as a port as the cone can be tuned to a spec frequency by adding/taking off mass. they are essentially a woofer without the powering componants (just basket, cone, and voice coil)

[Superjay]

actually, the passive is a basket, diaphragm, surround, spider and weight...no voice coil. essentially it creates constructive interference when tuned properly. When not tuned properly it creates DEstructive interference. it is very easy to not tune properly.

[fritosaregood]

Passive radiators are not that hard to use.

You can tune it just like you tune a ported box. the way you tune the is by adding mass to the radiator, so its mass equals the mass of air inside a round port of the same volume with the length needed for the desired tune.

you generally need twice the displacement in passive radiators as you have in active subwoofers.

pros that i now of are: space savings, no port noise, essentially as easy to build as a sealed box.(build not design), easily allows you too adjust tuning.

cons: it wont make for a high spl box, and you have to make the box to fit a 12/15/18" radiator where it might have been easier to do a 4" wide port

Ive even made a passive radiator setup out of a blow top assembly from and audiopulse axis sub, it turned out to be the perfect mass for my tuning, and worked out great.