This speaker uses the same bass driver crossover as Troels Gravesen's Eekel speaker which creates a third-order acoustic rolloff.
The tweeter has to be heavily padded down to meet the low sensitivity bass driver and also uses an acoustic third-order rolloff. The crossover frequency is just under 3000Hz which is slighty higher than Troels' but the Seas Nextel driver has no problem playing this high.
The combined response shows a slight hump in the bass range which appears in Troel's measurements as well if not so pronounced. The size of this bass hump is partly due to my imperfect measurement location which results in reflections.
I also modeled this by looking at the response with the tweeter inverted to ensure phase alignment. As you can see the tweeter has a deep null when inverted.
All in all this is a nice but inefficient speaker. It is capable of playing quite loudly but my next step will be to go active with one of the Hypex two-way digital plate amplifiers and use them as near-field computer speakers.