The SI driver has a frame like the Alpha, but everything else is different. The cone is covered in concentric rings from one edge to the other. The Qts is around 0.9. The XO point is around 2500Hz, give or take a few.

The origional speaker that Darrel Hawthorne done his experimenting with was an Alpha. The results were so good that he worked with Eminence to develop a coaxial driver with all the strong points of the Alpha but even better suited for OB coaxial use. The engineers at Eminence came up with the present Siver Iris, which seems to be a great OB speaker. Those that have the origional XO really need to get the new one to really hear what these drivers can do. The origional XO had some serious problems. It was not an Eminence design, BTW, but from an independant company.

I'm keeping my SI for a long time.

Dave