Passive radiator confusion

[Jzett]

I'm building a box for my sundown x 15 and am going to be using a passive radiator instead of a port. I need to know how big my PR needs to be. Could I use an 18" PR with the same xmax or would i be able to save a bit of money and get a 15 with double the xmax? Or would i simply have to use two 15" PRs?

 

[timofred]

No expert, but I think I remember that the PR should be 50% larger in surface area ?

 

[Jzett]

So I should get the 18" PR then?

 

[Gibsonian]

Yes, two 15's or an 18, either would work ime.

 

[Jzett]

Awesome, thanks for the help guys!