First you must decide what exactly you wish to do. If you are wanting to build a car audio system for a daily driver (the car you drive back and forth to work) with good sounds, but you are not interested in competing, a system can easily be put together for under $1000. However, if you are looking for the all-out bass monster, be prepared to drop in some big bucks into your system.
One of the most important things to keep in mind when building a car audio system is planning. Get an idea of where you are going to place components, subwoofers, amplifiers, and power distribution. A lot of headache can be avoided with the proper planning!!
For the basic system, lets look at some of the components needed.
Let's first start with the head unit (CD player). Obviously you are going to want a nice head unit. If you start with a good quality cd player, and choose to upgrade your sound system in the future, purchase a head unit that will grow with you. Some of the features you may want to keep in mind are:
1. CD changer controls
2. XM / Sirius controls (if you decide to add Satellite radio in the future)
3. Dual RCA outputs (carries signal to the amplifiers)
4. Pause button (important for competing)
5. Detachable face, or other security devices
6. High voltage line driver - this will send the sound signal at a higher voltage to your amplifier/s reducing noise and improving overall sound quality.
After you have chosen your head unit, you will want to make a decision on amplifiers and subwoofers. Keep in mind that you get what you pay for. A $30 subwoofer will be as big as a $300 subwoofer, but the capacities of each will differ greatly. Look at the power handling of each subwoofer and decide accordingly. You will want subwoofers will work with your amplifier/s (see compatibility).
You must also keep in mind the available space in your vehicle. Are you willing to give up your entire cargo area? How many subwoofers will fit? Decide on the size. Sizes will vary from 8" up to 18", some are square (Kicker), but most are round. Also keep in mind the resistance (ohms) of the subwoofer and make sure they are compatible with your amplifier/s (see compatibility). The subwoofer decision will also have an effect on the enclosure you decide to build or buy. For the basic system, I would recommend purchasing a pre-fabricated subwoofer enclosure. This will save you a bit of money and headache (especially if you end up building it two or three times!!). Make sure you take accurate measurement of your cargo area before building or buying an enclosure!!
Other components may be needed depending on the type of system you are building and how elaborate you want your sound to be. For the competition vehicle, figure on upgrading your alternator, adding a battery to your system (maybe more), running high quality RCA cables, power cables, ground cables, and speaker cable. You may need to add a capacitor to provide your amplifier with a reservoir of power for bigger hits from the subs. You may need an electronic crossover, an equalizer, replacement factory speakers, an amplifier for your mid-range and tweeters, additional speakers within your vehicle for staging, etc.
