This again refers to the early 12" field coil version as in the 1945 patent which is quite a bit different than the larger 15" version which the Speakerlab "K" was cloned from.Gives me the willies that Speakerlab was so blatently uninformed about what they were doing! Blindly copying.
But at least its not a bad copy, anyway. Couple of improvements, to boot!
DM