Unfortunately, dual voice coils is not an option. I'm building a force feedback chair of sorts and am using a bass shaker for the low end vibration. When looking at the application I dicovered it would basically use signals that look very much like audio signals (obviously it would need to be optimised later). So. I'm running any audio signal through a cheap DIY chip-amp and then into the speakers/shaker. But I need to xover and sum the signals to the shaker.
The more I thought about it, would it work to build two crossovers and then common the signal line of the load side of each xover (on the low fequency output) to the shaker?