Originally Posted by
Horn Fanatic
Since you're starting from scratch, and you have the A7's, I would load them with the 515. There are folks out there who load the A7 with the 421, but that driver is not a decent horn loader either. If you had scored a deal, and wanted to use the 4560 I would have suggested the 2220 or E130. Mr. Widget is correct, the later model ( after 1974 ) ALTEC 15" speakers are larger, but the 16 inch frames will fit on the A7 baffle with 1/16 inch to spare between the inside top panel. The A7 and 816 baffles are the same dimension, and the newer frames were used in the 816.
If you have the wherewithal, I'll suggest that you contact Bill Hanuschak at Great Plains Audio for a nice new pair of 515-8G's, rather than take your chances on an Ebay sale for speakers with no warranty, and possibly re-coned with after market kits.
H.F.