It's going to be hard to explain this over the internet, I kind of have to draw you a picture but here goes: on a dual voice coil sub there are in fact two sets of negative and positive inputs, one on both side of the speaker.
But then you ask the question: The back of the box only has two sets of inputs to run out to my amp what now? Usually a dual voice coil setup can run using 8 ohms which is good becuse you have the ability to bridge with out damage to the amp and get good strong sound out of the subs. Remember that when ever you bridge an amp you cut the ohm load into half, so if you have 8 ohm speakers you now will have 4 ohm speakers. You have to find a two channel amp that will be a stable bridge and will run off 4 ohms, you gotta read the specs of the amp though. When it says run 4 ohms don't run anything lower or higher because you will burn that amp up, they have those ohm loads there for a reason.
So how to I set up the speaker? I am going to tell you how I have mine set up. This set up works, my car bangs and I only have two 12's and I get comments about it all the time, not to mention all the numerous stereo violation tickets I have from the cops.
On the back of the speaker the positive and negative inputs will be off set form each side, meaning one side will be positive - negative and the other side will be negative - positive.
1) You run a piece of wire from one positive side to the negative side of the speaker, over the magnet.
2) Then from the other inputs run those positive and negative wires to the back of the box like any normal sub.
3) Run the wires from the back of the amp and bridge that bitch and you will have mad power to run your sub, but watch out for those damn cops!!
I hope I didn't lose you, I really need to draw a picture. Email me if you have more questions, I might be able to draw a piture and scan it onto my computer and send it to you. Good luck!
