If I remember correctly, Fried produced a version of their model C satellite speaker (C-6?) with a special crossover and dual voice coil mid bass drivers. There was a way to connect the two speakers so that the second voice coil was out of phase and was supposed to enhance the spatial presentation of the speakers. It was specific to those models that had the specially designed crossover though.
I believe VanL speaker works out of Chicago had a speaker that did something similar. I don't remember the model though.