Does not quite meet the parameters you posted, but very impressive low frequency extension for speaker type and cabinet size. Smaller footprint then the majority of stand mounts.
http://www.decware.com/newsite/HORN.html
Scroll down the page for specifications.
No affiliation with Decware
http://www.decware.com/newsite/HORN.html
Scroll down the page for specifications.
No affiliation with Decware