I have exactly 1.5 cubic feet total internal volume available for an enclosure. My choices are to either do a ported 12" with a net volume of 1.31 ft^3 after sub and port (round 4"x7.5", as a slot port will take too much volume...port noise is worrying me as well) displacement. This will give me a tune of 42 hz.....or....I can use a passive radiator and essentially tune where i want, but will cost 80.00 more. What's the major drawback to the passive vs. ported system except cost?

 

passive radiator gives u the spl of ported but with the sound of a sealed box.. and u can tune the passive using the weights that they supply.. easier to tune anyway... if its available to u with the sub ur running id go for it

 

How many passive radiator systems do you see on the market compared to vented? If the results outweighed the cost and effort, you would see more, but they don't.

 

home theater seems to have more of them

 

Yep - there someone has spent the time to make a static enclosure, tuned the PR, and then cranked out copy after copy. Not so well suited to car audio. Vent chuff is a bigger issue in home audio as well.

 

PR has a steeper roll off. I don't know if the sub can become unloaded, can it?

 

A steeper rolloff? Please explain how.

Both the sub and PR can unload.

 

My bad I was thinking bandpass.

PR is -18db per octave.

Sealed -12, ported -24.

 

Bandpass is 4th order as well, -24db/octave, at least on the top end. If it is a sealed bandpass, the bottom end is still -12db/octave.

How does a PR achieve 3rd order rolloff? Link to that info?