In Reply to: 511's in a three-way posted by Wayne Parham on June 16, 2003 at 11:37:39:
You may be interested in the referenced Altec page that advises crossing over the 902-A at 1200 Hz on the 511 or 811. http://nleinternet.net/alteclansingunofficial/proloudspeakers/sectoralhorns/511B&811B-Data.pdf