What crossover for this:

try this

You may try the following. We used it in an 11 L resonant box with 130 cm wo + 25 mm tw (units similar to those you inform, but Seas brand).

Lopass: 2,5 mH series inductor (0,9 ohms resistance wire) + 35 microF parallel capacitor.

Hi pass: 7,3 microF series capacitor + 0,7 mH parallel inductor(0,44 ohms resistance wire).

Note: to balance units sensitivity was necessary to add a series resistance 4,7 ohms /10W to the tweeter at the hi-pass output.

You may need to change this value. What I do is measuring the output sensitivity of each one with a radioshack sound meter, feeding them with TV audio signal of a non broadcasting (or empty) channel, that gives white noise.

I am sorry but I am a poorman.

I hope this could work for you.

Kind regards.

Hugo