dvc means that there are two voice coils instead of one (I know, I'm a genius) -- but seriously: you can run twice as much power to the sub by connecting 2 amps.(if you want to, but that's rarely the case except for competition) you can run both vc's in series to double the impedance if your amp is not stable for the rated ohms of the subs vc's you can run the vc's in parallel, effectively cutting the impedance in half. this makes your amp "seem" more powerful but is dangerous to equipment that is not designed to do so. most amps that you buy will list rated power at different loads. for example- THIS IS NOT REAL GUYS, DON'T PICK ON ME remember that you can always run an amp at a higher impedance than it's rated for without damaging the equipment, but you can rarely get away with going lower. anyway, example: you buy a 1200 watt one channel amp, and hook it up to one 8 ohm sub, the output may be something like 400watts in that setup. you hook it up to two 8 ohm subs, wired in series (thus giving 16 ohm impedance), then your amp outputs 300watts (yeah, I suck at math!) you hook the same subs up in parallel, the amp may output something like 900watts, because the load on the amp is now 4 ohms. you take one dvc sub which has two 4ohm vc's, and hook them up in parallel so that the impedance is 2 ohms, then your amp should be outputting close to 1200watts (provided that the amp is rated as being 2 ohm stable.) it's just a way to get more power to the subs because voice coils can only handle so much power, and they are all made differently. remember that I am not quoting any specific manufacturer and am pretty sure that my example figures are nowhere near accurate, I'm just using them to signify increase/decrease in an attempt to explain the purpose of dvc subs. in short, a dvc sub has two inputs that can be wired seperately if desired, but this is hardly the case.. people usually use them to make a 2 or 1 ohm sub that can take lots of power. I run 2 8 ohm dvc's in parallel with themselves (to make 4 ohms each) and then parallel with eachother (to make 2 ohms total). hope I didn't confuse..
basically dual voice coil makes it so you have more wiring options avaliable for hooking up multiple subs and trying to hit a certain target impedance. sometimes the power handling does not go up due to 2 voice coils because they can only fit so much wire into the magnet structure and they rest of the engineering is the same so the vents and other pieces that help with power handling are the same, so only a certain power handling is avaliable.
you have to be careful with 2voicecoil drivers because the parameters are only correct if you hook up both coils in parallel. If you use only 1 coil or in series you get completely different parameters! I am happy to calculate the new parameters for you if you want. Ok you can match the impedance better, correct. However the powerhandling does not really change if you use a single coil with the same impedance and same wire length and total layer height as with a dual coil in parallel (or any other way). This is a bit of a misconception. Those who do not believe that can have the mathematical proof from me. All in all: if you want an 8Ohm (nominal) woofer then a dual coil is of not much an advantage. If you want to hook up 2 amps together on one woofer, then a dual coil comes in handy.
Basically what everyone is trying to say is: Dual Voice Coils = more variety to wiring options to amp(s) No change in power handling if same sub is single or dual voice coil
