Seamless Stealth Subwoofer
The SpeakerCraft Seamless subwoofer is a rectangular surface and has more cone moving bass creating surface area than a 15" comparably sized round subwoofer.
A rectangular subwoofer will sound louder than a traditional 15" round subwoofer because the four corners give you more moving air capability with greater cone area.
The extra surface generates a higher frequency response as well. For a speaker that is 100% invisible the amount of bass response is tight and accurate all the way down to 20Hz.