This is a list of the other places/things that were helpful to me in the search for loudspeaker design formulas, information, parts, and tips. Each list is organized according to your design experience - that is the first item should be considered as a fundamental item or necessary to understand the items following it. I will be adding more information and links to some other excellent websites soon.
Books
How to Select and Use Loudspeakers and Enclosures - Murray P. Rosenthal Hayden Book Company, Inc. Rochelle Park, New Jersey ISBN 0-8104-0831-7
Great Sound Stereo Speaker Manual with Projects - David B. Weems TAB Books Division of McGraw-Hill, Inc.
Blue Ridge Summit, PA 17294-0850 ISBN 0-8306-3274-3
Audax Industries You will have to purchase from one of their distibutors, but this site has excellent information on the high quality Audax product line.
Audio Concepts, Inc. (ACI) 901 South 4th Street, La Crosse, WI 54601 608-784-4570 Drivers, parts, and kits. Check out my home-theater subwoofer design using the AC12DV.
Madisound Speaker Components 8608 University Green, PO Box 44283, Madison, WI 53744-4283 608-831-3433 Drivers, parts, and kits.
MCM Electronics 650 Congress Park Drive Centerville, OH 45459 Toll Free: 800-543-4330 Everything related to electronics.
Meniscus Audio Parts, speakers, accessories. Excellent products. Some products exclusively available from Meniscus.
Old Colony Sound Lab P.O. Box 243, 305 Union Street, Peterborough, NH 03458-0243 603-924-6371 or 6526 Everything for audio design work - except components.
Parts Express 340 E. First Street, Dayton, Ohio 45402-1257 513-222-0173 Parts, kits, and speakers.
Solen Electronique Inc. 4470 Thibault Ave. St-Hubert, QC J3Y 7T9 Canada 500-656-2759 In my opinion, the most cost effective capacitors. Excellent selection of inductors. They also sell drivers.