These are single voice coil. All JL Audio woofers are single voice coil except W6 and the 13w7.

a voice coil is the electromagnet that causes a speaker horn to move in response to the electrical impulses received from the amplifier.

They will either pull in or push out depending on the polarity of the DC voltage and remain stationary.

This is a bad idea as the DC resistance of the voice coil is much less than the AC impedance of the voice coil and it is possible to overheat and burn out the voice coil due to the much higher current the DC voltage can produce in the voice coil compared to the AC voltage that would drive the voice coil in normal operation.

When connecting a dual voice coil sub in series you should use the powered subs.

There are a few types of speakers, but generally, the "voice coil" type speaker is the most common used for sound systems. It consists of a strong and lightweight paper or plastic cone which is attached to a coil. The coil is aligned so that it surrounds a magnet, but the magnet does not touch the coil. When a voltage potential is connected to the voice coil, the coil and therefore the cone moves. By applying voltage at a specific frequency, the voice coil will move in synchronization with the electrical frequency. The voice coil can be moving slowly, as is required by a low frequency sound, and at the same time a high frequency electrical signal can also be injected into the signal. By overlaying multiple electrical frequencies at the same time, the voice coil will move to produce a wide range of simultaneous sounds.