Project May has undergone quite a few changes since the original idea presented by Mike Baker back in November of 2003.
First it was based on the old JBL 434x 4-way loudspeaker systems of the late 70's and early 80's. Then Don got JBL involved and it changed into a "K2-S9800 system with an extra pair of 1500Al's". I'm not sure what conversations Don had with JBL but I am quite sure of the conversations I had with JBL and it was pretty much an exercise in futility from the start. We moved ahead anyway.
Some folks wanted to stick a 10-inch driver in between the 1500Al's and the H9800/435Be for various reasons. Greg Timbers' response was "won't work" and the 10-inch drivers were not added to the complement. We could have bought a pair on our dime anyway but we didn't.
During this time Greg was just starting work on the Everest II system. He measured the dual 1500Al's in the anechoic chamber, along with the prototype network on the second 1500Al "helper", and passed the information on to me. I incorporated that prototype filter into the prototype K2-S9800-based filter and sent the whole thing to Mr. Widget. If I remember correctly, no one at the first listening session cared for any of it.
The dual 1500Al's weren't going to work for JBL so they came up with the dual 1501Al's. These drivers had a larger gap to increase power handling as well as a higher impedance to facilitate using in pairs. Same concept as the 1200FE-8 (4428) and 1200FE-12 (K2-S5800).
We are pretty much stuck with the 1500Al's and that means that Don is going to have to use an amp that doesn't have any problems driving a low impedance load.
It has taken us no less than a year and a half to obtain the replacement 1500Al's (two were damaged and JBL didn't have replacements at the time) and the new 476Be's to replace the 435Be's and 045Be's.
The delays in the Project have actually been quite fortuitous. The Project now consists of dual 1500Al's and the 476Be on the H9800. Don can run the system in MTM format or 2-1/2-way format. The biggest news is that we have finally found a craftsman to handle the responsibilities of the former Enclosure Team. I expect to get with him in the next six to eight weeks when I can make the eight hour drive and we'll get started on assembly of the final enclosures.