Quote Originally Posted by Art J. View Post
Altecs solution was the 30923 slope attenuator board added to the horn circuit to tame it down for home use.
Best solution.
Personally, I believe 'best' would be driving them with a ~matching impedance SET amp to get the desired CD horn EQ , with second best being an electrical filter equivalent for a very low output impedance; though I doubt the 30923's component values designed for the more efficient 802 are going to be acceptable for the 806 due to its lower gain BW, faster HF roll off, but not aware of an 511/806 variant.

As you noted, there's still the issue of woofer/horn time alignment at least at the XO point, so for a passive solution, what's really needed is a M19 style XO that effectively has the proper CD horn EQ plus electrical offset for the longer 511 horn, but don't recall seeing one.

Seems then that for the casual DIYer, adjustable active XO/TD is the way to go with this combo.

GM