I've been trying to figure out what to do with my 18 XXX. I finally decided on a 4-5 cube sealed box, depending on how large an area I can fit in my trunk, but the 4-5 cubes are the definite range. I was going to go just sealed, but love low end & was wondering if I could do passive radiators w/ the xxx.

Corey don't kill me for makin this post, just figured it'd help!

By the way, if any of you end up not liking me one bit, blame Corey A., he's the one who told me to come here.

Anyway, thanks for any help or any insight in this idea.

You could do passives... but you would need some HUGE passives to work with the XXX.

Don't worry about low end sealed... it will be there

I have read the passives need to double the cone area of the 18. It is also a matter of I want to do this. Sealed is fun & I'm not ignoring your advice at all, but wondering what the possibilities are with the pr's. I've never got to use them before & thought it might help w/ my box size also. Every time i measure my trunk it just seems to get smaller, lol.

thanks for the quick reply jacob!

It certainly won't make the box any smaller than a sealed box

You can try it if you like... those will have to be some hefty 18" PRs.

I have read the passives need to double the cone area of the 18.

The PR needs to be at least double the swept volume of the driver. So if your 18" has an xmax of 30mm, then the 18" PR needs at least 60mm of 1 way travel. Most I've seen stop around 40mm so you would need a pair of them. Remember that PRs need to mount on a vertical plane. Their weight would cause major cone sag if you mount them horizontally.

TC Sounds and AE Speakers are the only two places I know that build PRs in this range.

-Robert

I can't think of a reason why you'd want to use PR's in a vehicle.

It can be done, but it's making things much more difficult than it needs to be...

reduce gross box voume, since the port would not be taking up space?

Use external ports?

I would use externals but I'm firing into the cabin & sealing off the trunk, so I don't have the room for external ports, plus I don't know if the 18 would like 4-5 cubes ported. I have 42" of width, which can be increased if I angle the baffles, so I can fit a pair of pr's i think.

What would be the big advantage to this, I am just assuming low end, but after seeing JimJ say it's pointless, i just want to know why, that's all. Cuz if this is too much hassle/work for no real advantage, then I'll def. not waste my time.

thanks for all the help so far guys!

BTW if I did get Pr's I'd get them from Fi, I was told they can make them. Does any one know how to calculate or could direct me in the direction of how to calculate how many pr's or what the pr's would need to handle.

I have the vertical plane to mount the pr's, thinking a pair of 15" pr's could handle the 1 xxx 18.

I feel so stupid for forgetting to post this, but the xxx 18 is an 02-03 motor w/ fi soft parts! HA! Wow, so yes, i am insanely dumb for forgetting to mention this!

BTW I'll have about 3500 rms @ 4 ohms going to the sub, not sure how the pr's affect the sub in terms of power handling.

Thanks again guys!

-nate

Well, after some great advice from jacob, i'm going to pass on the pr's & just do the box sealed. I'll take pics of the build, should be within the next week or so. Whenever corey gives me my opti amp & fi sends the sub to me

Thanks for all the help!