Placement of PR on a sub box

[Stantob]

I am planning to build a sub with the classic Peerless XLS and a passive radiator. PR is new to me and I have searched the net to learn. But one thing remains unsolved to me. I have seen solutions where the passive element is facing all directions.
Doesn't this have any influence on the construction? Phase problems? I want to place the PR on the same side as the main element, pointing downwards.
Does the distance between the elements have any importance?
Thanks!

 

[simon5]

A passive radiator is usually VERY heavy so pointing downwards is usually a very BAD idea.

If you crossover low, the PR can be anywhere, even behind.

 

[Stantob]

Didn’t think of that! Is it the same problem with XLS drive element pointing down? A solution could be using a vented system. A long vent should not be a problem in my design.

 

[simon5]

You can have the XLS pointing down if you have less than 5% of sag.

It's mostly a problem with PRs, but some drivers can't achieve less than 5% of sag too.

You can't use a frontfiring PR?

 

[Stantob]

It is more of an aesthetical problem. I want the speaker to be "invisible". Two 12" elements poining at your fase is not.

 

[simon5]

But the woofer under and the PR behind, as long as you doesn't put the subwoofer too close to a wall it will be ok.