I'm probably wrong, but the limited literature I've been able to find on the EV SP-15B indicates that it's closer to the SP-15, both with whizzer cones, ceramic mags, stamped-steel baskets, and intended for hi-fi use. The SP-15 even had a midrange/treble control. The SP-15A has a cast basket, and an Alnico mag (I think).

You may well be right that there is little difference among them, but in one piece of EV lit I found regarding the SP-15B, it was suggested that it's best use was in an infinite baffle. If I understand that application correctly, which I probably don't, then it might be that the SP-15B has a much higher Qts, making it a very different animal.

I think I'm going to get that woofer tester from PE.

Thanks again for the link ... I found info on several other speakers I was having trouble finding.

Happy Thanksgiving to all!

Best,

Jim