What parameter makes those drivers designed for open baffle and not suitable in a closed box? What is it missed in the simulation?
Good point.
Nothing prevents from using the L26RO4Y in a variety of box alignments. Maybe sealed is not naturally optimal, but you can do lots of great things with sealed plus EQ.
Here is the info from the Madisound website, which is apparently quoting Seas, with an odd quote from SL in the middle:
"The L26RO4Y subwoofer. Developed in cooperation with Linkwitz Laboratories in Corte Medera, California, the L26RO4Y saw its first application in the highly acclaimed Linkwitz ORION open baffle loudspeaker, and is currently used in the Linkwitz LX521. The L26RO4Y substantially improved the ORION's bass performance and dynamic capabilities, and has since been incorporated in all Linkwitz lab designs. We at SEAS are also very proud that the ORION, LX521, LXstudio and LXmini+2 loudspeakers use all SEAS drive units!
"There is more to a woofer than its published TS small signal parameters and X-max, derived from mechanical measurements. In an open baffle, a woofer operates in the large signal domain; and its distortion, dynamic stability and limiting behavior determine the sound. An open baffle is the most demanding and difficult environment for a long throw woofer." -- Siegfried Linkwitz
To meet these stringent demands, the L26RO4Y subwoofer builds upon the already excellent chassis, magnet system, cone, and surround of our L26ROY. An all new FEA designed spider and 4 layer voice coil wound on a stiff glass fibre former have been employed, resulting in a driver with ultra long throw, very low distortion, and extremely stable mechanical operation under all conditions; including open baffle systems. The low Qts and Fs are ideally suited for active open baffle bass systems, but the L26RO4Y can also produce excellent results in enclosure based subwoofer and multi-way systems."
More importantly, here are the datasheets with the TS parameters (despite what SL said!!!):
Clearly, the L26RO4Y is going to work in a range of applications. I know little about open-baffle, it seems the key here is lower compliance and higher moving mass with the same resonance frequency as the L26ROY sibling, with slightly more linear excursion capability.