Nelson Pass, I’ve heard these speakers and 2 or 3 slightly different versions.
Single concentric drivers every time. I love horns.
Now if mozartfan would pay just a little attention he might see something interesting for a dual purpose single chassis driver and a well designed horn. 7 watts with a 101 sensitivity is incredibly loud..
If you looked up through the throat they weren't matched very well at the flange connections. We matching the ports on ours. That top "U" had highland sheep wool. The best sounding was rough coat the last 18" or so of the outlet. I ran mine with MC240 Macs. Just about 30 watts to much. I wish I would have had a MC225 at the time. That would have been the ticket.. :-)
Not according to Mr Pass though. :-)
He was designing Threshold at the time I think.. It was a while back.. Sure supported his products through the years. See him just popup in a Pass talk group..
Regards