After much listening, tweaking, changing, and even an unintentional mistake that led to the final product, this is the current crossover schematic for the 2241H/2251J/Heil AMT.

The unintentional mistake that led to an unconventional wiring arrangement lets the 2251H sing so clearly that the detail is unreal, probably about the best I've heard, certainly in my home at concert levels. (Perhaps the Harbeths that were here for a day or my LS3/5s sound better at lower volumes, but I've not done a head-to-head comparison.)

If you look at the schematic you see that the 6.8 mfd cap for the 2251 actually attaches to the woofer's positive lead rather than directly to ground. The connection was supposed to go to ground (the other side of the 47 mfd cap), and did in one crossover. But I accidently put the wire on the wrong side of the cap in the other crossover, and in head-to-head comparisons, one was head-over-heels better. (Had to figure out why.) This works with the wedgie in the AMT and the UHF control brings the "air" back in, not that there's not plenty without it. But when I would listen to the 2405 I could hear more "top end sizzle." This takes care of that top end without adding sibilence, and the 2405 looses its advantage here.