Are there any differences between the Altec 515 & JBL LE15 15" woofers?

[Ronald Lee]

I now the 515 has a 3" VC, and the LE15 has a 4" VC.

[speakerdave]

I now the 515 has a 3" VC, and the LE15 has a 4" VC.

Assuming you mean the 515b I would say these woofers represent two different schools of thought, and intended application, on woofer design. They have two similarities. Both have under hung voice coils and both had Alnico motors in their original versions. Everything else is different. I would suggest you begin by reading the manufacturer information about them posted on the Lansing Heritage website (for the LE15 read about the 2215 version in the pro driver section-it's the same). Then find their listings in T&S charts. Even if you don't understand the significance of all the parameters this will give you some sense of what the two woofers are about. Then look at the ways the manufacturers deployed them in speaker systems as well as their cabinet recommendations for DIYers. Also, a pleasant couple of hours can be spent following the catalog history of the two at the same website. Finally, the LH forum site, this one, Audio asylum, diy audio and other online audio discussion sites will all have past threads on these two drivers, threads that you can find using the provided search engines. There's a lot of legwork you can do for yourself in answering this question.