The Equalized Quasi-Sealed System - EQSS™ - is a patent-pending method for achieving improved bass response in a loudspeaker. It combines the best features of a sealed system and a vented system. The method is employed in the Athena speaker system and also in the EQSS™ subwoofer, described elsewhere on this site.

A White Paper describing this technique can be found here. It includes much more detail than the earlier description and also includes several application examples.