There are many different types and sizes of car subwoofers on the market today. While the quality of standard OEM sound equipment has improved over the years, you still need some sort of subwoofer in the system to produce that rich sounding bass that most of us are fond of when listening to our home stereo systems.
You can find subwoofers ranging in size from 6 inches up to 18 inches in diameter from dozens of automotive electronics companies. Many times a shopper will purchase a specific brand sub in the largest size available thinking that "bigger" must be "better". Then after getting it home, they realize that they have no room to devote to the enclosure that is needed, not to mention that they failed to budget for the powerful amplifier they'll need to power their beast.
Planning ahead is essential when upgrading your car audio system with a subwoofer. But it can be quite rewarding and enjoyable if you follow a few simple suggestions. If you are limited on available space and simply want better bass then your standard full range speakers are capable of, then you might consider one of the amplified enclosed subs. These are easy to install and you'll find them available from companies like Boss, Infinity and Bazooka. They are small six to eight inch subwoofers installed in small enclosures or tubes and they have a basic amplifier integrated into the unit. Considering that they offer a sub, enclosure and amplifier included into one small package, they should be your least expensive option while providing the smallest footprint in regards to space.
But if you enjoy rap music, popular music or just about any music where you want deep bass which can vibrate the windows, then you'll probably want to go with separate components. Years ago a buyer would have to go with either a sub made for SPL (loudness) or SQ (musical sound quality) and this is usually related to size, but today there are a few subwoofers available which are well known for both.
So the first place to start when shopping for a subwoofer setup is to determine just how much space you want to dedicate to your subwoofer enclosure and amplifier. You can do this by starting with smaller subs such as 8 inch. Read their specifics and see what type and size enclosure your selected sub requires. There are two basic types of enclosures which are sealed and vented. The small sealed sub boxes will be smaller then any vented box in most circumstances. So if you start looking at sealed enclosures you'll get a good idea of the minimum amount of space needed. In most cases, the larger the subwoofer, the more air is moved so the more bass is produced.
Your second step would be to see the power requirements of your selected subwoofer. Just match the suggested power and match it to a power amplifier. Look at the exterior dimensions of the amp and realize you'll need a bit more space for air circulation and wiring and this will allow you to estimate the space needed for your own subwoofer setup.
As you can imagine, even a twelve inch subwoofer and amplifier installation could eat up a good amount of trunk or hatch space in modern vehicles. You can find a variety of subwoofers from brands like Alpine, Boss, JL Audio, Kicker, Lanzar, MTX, Pioneer and Rockford Fosgate just to mention a few. Many provide slim mount or shallow mount subwoofers as well as standard subs. The shallow subs allow mounting in smaller boxes which may be mounted behind or under a seat in some applications.
So you should not be intimidated by the decision making process. There are other options to consider such as single or dual voice coil subwoofers and the benefit of each. Generally speaking a dual voice coil model subwoofer will enable more flexible wiring options and this is especially important when running two or more subs.
From my experience over the years, 10 inch subwoofers are the most popular and will provide you will a huge variety of factory made subwoofer enclosures to choose from. Besides the standard sub boxes there are many special fit enclosures made for specific cars and trucks. When ever you find a custom-fit application you'll see you can save on space since they are made to fit into areas of wasted space in vehicles.
Again, if you follow the simple steps of estimating your allowed space for subwoofer and amplifier before purchasing, you'll be much happier with the end results. Buying car subwoofers can be easy and fun.