Quote Originally Posted by valhallax View Post
could have sworn the 413 had a 4 inch voice coil....
Only the 411, nearly everything about the 411 is unique and not shared by any other Altec woofer, even the frame is different and only shared by one or two duplex ceiling speakers(950-xx?).

Martin, there might be specs posted at the T/S website, but i'd take them with a grain of salt as they could be a very "novice" submission and far from accurate. Your best bet is probably to seek someone local to you with analysis software/set-up and run the gamut on both your woofers.

A quick search here at Hostboard will bring up some informative threads on 413. It's production span was so brief that "official" specs may have never been published.

Just my .02............................

EDIT: http://www.thielesmall.com/default.asp The entries here look like they were basically copied from the "unofficial" Altec site list of T/S parameters, no 413 listed.