Vifa xt25 & p13

Have made several pairs trying different XO configs. My conclusion:
For moderate SPL's and a small enclosure, a simple two-way using 3rd order filter works well, but don't expect much bass from a single P13 in a sealed (fc=110hz)box.

For higher SPL's, consider an MTM (along lines of Ariel/ME2). A ported box (Fc=75Hz) or X-line will bring up bass response.

Still, expect to use a woofer/sub below 80Hz.

For a tried and proven XO filter, see:

http://www.quadesl.com/okara.shtml