Dual-Cone Speakers
Some factory installed and replacement auto source speakers are of the dual cone type. Sometimes also referred to as a "full-range" speaker, it uses an inexpensive, but efficient design. The small "whizzer" cone attached to the center of the main cone extends the high frequency range, but not with the wide dispersion or intensity of a separate tweeter driver. The main advantage of such speakers lie in their low cost.

Dual-Voice-Coil Or Dual-Channel Speakers
These are woofers with two separate voice coils mounted on a cylinder connected to a common cone. These are most often interconnected so as to allow the woofer to handle a lower impedance load at it's optimal power capacity.

They can also be connected to separate amplifiers in order to produce a common bass wave from two amplifier channels through a single woofer. Since bass has a non-directional character, this does not interfere with the optimum reproduction of the stereo image in the other speakers. Thus, a correctly configured single driver can often provide as much bass as multiple drivers, and in a smaller enclosure.

Great care should be taken in making connection from the amplifier, to observe proper polarities, especially when conected to separate channels. Failure to do so, can result in the quick extinction of the driver if the amplifiers are pulling the voice coil form in different directions at once.

Impedances for these speakers can be configured in a variety of values including different levels for each one. The most popular format is to have each coil optimized for 4 ohms, although 6, 3, 2, and even 1 ohm coils are not uncommon. Some specialized units may have 4 and 2, or 8 and 4 ohm coils, although these are fairly rare and usually proprietary designs.

The same considerations of enclosure volume, power handling, and frequency response apply to these drivers as they do to all others.