Some people have emailed me offline especially about the differences between the 15-ohm and 11-ohm versions.
I am starting this thread with a visual guide to identifying the 15ohm and 11ohm versions. Please chime in with your other tips and experiences so we can compile a knowlegebase on this topic.
First off, there are the 15ohm and 11ohm versions. These are not the ratings of the main B110 driver but a combination of the T27 tweeter, xover and B110.
There are so-called Rogers pseudo-15ohmers. These have been documented to start at serial no. 321xxx. Earlier serial numbers by Rogers are REAL 15ohmers. Those after this cutoff are actually 11 ohm units but mislabelled as 15ohms. The common belief is that Rogers had excess 15ohm labels and just pasted them on the new production (at the time) 11 ohmers.
Aside from the serial number, how would one identify a 15ohm unit vs an 11ohm unit? I compiled the image below to show the differences:
I'll add other photos, especially of the xovers later on. Feel free to contribute.