Top 10 Car Audio Components

Speakers are the basis of any car audio system; without them, you'll hear nary a thing but wind, the hum of the engine and the bustle of traffic. With speakers, our cars come alive with music. They work by translating the electrical signals from an input like a CD into vibrations that our ear registers as sound.

Not all car speaker systems are alike. There are two primary classifications of car speakers: coaxial and component. Coaxial speakers are what you'll commonly find in a factory-installed car audio setup -- in other words, unless you've installed a custom audio kit in your car, it likely has coaxial speakers. A coaxial speaker consists of a woofer that produces low- and mid-range sounds and a tweeter that sits atop the woofer producing high range sound. Superior coaxial units will add extra tweeters to better reproduce the high range sound.

Component speakers are comprised of several separate units -- the woofers and tweeters are not built together into one part. Component speakers also utilize a crossover network to direct sound to the right speaker units, producing superior sound quality. The crossover network helps component speakers deliver better audio than you'll get from an average coaxial setup. Because of that advanced crossover network, component systems don't need as many tweeters as coaxials to produce high-quality sound -- a two-way component speaker setup is as good or better than three-way, four-way or five-way coaxial speakers. Not surprisingly, component speaker systems can be pricier than coaxial speakers. No matter which kind of speaker system you're interested in, there's a huge price range: Inexpensive coaxial and component sets can be had for $20 to $40, but high-end gear can cost in the hundreds of dollars -- or more! Look for some popular audio brands like JL Audio, Alpine and Infinity.

Now we come to the classification of speakers we love best: subwoofers. If you've ever been to a nightclub and felt the music pounding in your ears -- or if you happen to have noisy neighbors who party way too loud -- you know all about the power of bass. Subwoofers are responsible for reproducing the lowest, deepest sound ranges that add body to any audio mix. Music just isn't the same without a good subwoofer.

We learned on the last page that component speaker systems consist of individual sound units connected together to accurately reproduce the sound from a CD, MP3 player or radio broadcast. Component subwoofers tie into the audio package, enriching the low frequency sound with powerful bass. As with coaxial and component speakers, you can spend hundreds of dollars on high-end component subwoofers. Two other necessary pieces of equipment will add to the expense: To install and run a subwoofer, you'll need a subwoofer enclosure and an amp (which we'll discuss later) for your system. The enclosure will ensure maximum performance from your subwoofer, while the amp will give it the power needed to deliver that deep bass [source: Sonic Electronix].

One word of warning about subwoofers: There is such a thing as too much bass. Crank it up too high, and you'll hear (and feel) powerful vibrations that distort the sound of your music. Find a happy medium that enriches your music with bass but doesn't rattle your windows with overpowering low frequency sound.

One of the most flexible, useful modern additions to car audio is the wireless communication technology Bluetooth. Most mobile phones, especially smart phones, are Bluetooth capable. They can use the wireless protocol to communicate with other devices and transmit data.

To use a car's built-in Bluetooth capabilities, simply enable your phone's Bluetooth radio and pair the device with the car. Take BMW's Bluetooth options, for example: Once you pair a phone with a BMW car, you can browse through your contacts with buttons on the steering wheel and use the car's receiver display to access the information on your phone. During a call, your voice will be picked up by a microphone in the car, and the voice on the other end will broadcast over the speaker system [source: BMW]. In states that have hands-free cell phone laws, built-in Bluetooth is an efficient way to stay in touch while your cell phone remains in your pocket.

Your car may not have come with the luxury of Bluetooth built into the audio system. If you're interested in Bluetooth, that's an easy problem to fix: Both Bluetooth and our next car audio component can be added to a car with a quality receiver, often called a head unit or stereo.

Car CD players haven't quite gone extinct just yet, but they're slowly moving the way of the cassette as MP3 players and smart phones become our preferred way to play music. It's a natural evolution: These new storage mediums can hold far more music than audio CDs, and 3G and 4G data plans allow us to wirelessly stream music from services like Pandora. But MP3 players and smart phones have been designed with headphones in mind, which means car audio systems need a way to interface with these digital devices.

Luckily, many modern cars now include built-in connectors for these modern devices. We already covered Bluetooth, which can wirelessly link with some devices to play music or handle phone calls. Car manufacturers like Toyota offer optional auxiliary audio ports in their car stereos in the form of a 3.5mm (1/8-inch) mini stereo jack that can plug into anything with a headphone port [source: Toyota]. Others include USB ports that can also facilitate music playback from an iPod or similar device.

Don't have a brand new car with an auxiliary jack or USB port built in? Don't sweat it -- that's where our next car audio component, the head unit, comes in. With this one piece of equipment, you can dramatically improve the functionality of your car audio system.

Receivers go by many names: multimedia receivers, car stereos and head units. No matter the name, the receiver is possibly the most important piece of any audio system. Sure, you won't get much sound without speakers, but it's the stereo that gives you control over music and radio, equalizer settings to tweak how your system sounds, and a way to interface with data on CDs, cassettes, smart phones, MP3 players or DVDs.

Receivers typically include displays to show you what your audio system is currently playing and buttons for switching inputs and presets. Car stereos adhere to certain sizes, which makes them easy to upgrade. If you're still using a plain ol' CD head unit in a 2003 Corolla, for instance, consider upgrading to a model with a multi-disc changer and a USB port for connecting to an iPod. Some receivers are compatible with satellite radio, which is a must if you're interested in Sirius XM. Of course, if you want a multimedia receiver with wireless capabilities, get a Bluetooth car stereo.

The head unit is the brain center of your audio system; make sure it enables all the functionality you're looking for. Next we'll take a look at an even more advanced system often embedded in car dashboards: GPS.

GPS, or global positioning system, helps guide you to your destination by pinpointing your location and referencing street data. Many smart phones today offer built-in GPS functionality, and you can easily purchase a dedicated GPS unit for your car. But to truly tie the advantages of GPS into your audio system, there's in-dash GPS.

In-dash GPS systems are essentially head units with GPS functionality. They offer large screens for viewing map data and they usually include the same features you'll typically find in a nice receiver, like Bluetooth and USB support.

Naturally, a GPS head unit tied directly into your car audio system will be able to pipe directions straight through your speakers. Today's more expensive cars will offer an in-dash GPS system as an optional extra, but you can always buy an aftermarket unit, too. Just like the head units we covered on the last page, in-dash GPS systems are readily available from a variety of manufacturers. Just keep in mind that they won't be cheap -- expect to pay several hundred dollars for a high-end GPS receiver.

By now we've covered all sorts of goodies that make car audio a more fun experience. We've hit on speakers that make car audio possible, subwoofers that deliver deep bass and inputs that enhance the listening experience. Now we'll take a look at how to make it all sound even better.

Subwoofers require amplifiers to deliver those low frequency sounds. Amplifiers work by boosting an audio signal into something powerful enough for the speakers to output. Think of an amp like a high-tech megaphone: Your mouth is the audio input from the radio/CD/MP3 player, the megaphone is an amplifier connected to your speakers, and the loud voice coming out of the megaphone is the sound your speakers can produce. Speaker systems need amplifiers to work, which means your car already has one, just like it has basic speakers built in.

But if you plan on expanding your car audio system with nice component speakers and a subwoofer, an aftermarket amplifier is a must. The power will give your audio new life; in fact, without a new amplifier, your audio system probably won't work at all. Each speaker needs an audio channel; while a two-channel amplifier would work for a two-way component speaker setup or a two-way coaxial speaker, you need more channels if you plan on adding more speakers to the component setup. And, of course the subwoofer needs its own channel. Amplifiers with four or more channels will work with a subwoofer and component speaker arrangement [source: ABT].

When choosing an amplifier, there are two ratings to pay attention to: RMS and peak power. RMS power refers to the amount of continuous power applied to the amp, while peak power rates how much power an amp can deliver during an especially loud moment. Think of RMS power as a steady rhythm, key to maintaining quality sound over the long term. Peak power is like a blaring trumpet blast: You want it to be as powerful as possible, but it's less indicative of the overall performance of the system [source: Crutchfield]. With an amplifier and all those speakers in place, there's still one key element missing: the crossover.

Tweeters, woofers, subwoofers -- each type of speaker has a specific role to play in an audio setup. The subwoofer isn't designed to output Robert Plant's high-pitched wails any more than the tweeter is designed to handle the low-pitch rhythms of an upright bass. How do we make sure each speaker is doing its job correctly? The answer lies in the crossover.

A crossover directs audio frequencies to the proper targets, making sure only high-frequency sound reaches the tweeters and low-frequency sound finds its way to the subwoofer. Simple coaxial speaker setups -- like the kind that come standard with a new car -- have passive crossover circuitry already in place. As we mentioned previously in the section on amplifiers, you won't need to add anything special to one of these systems. But if you plan an upgrade to component speakers with an amplifier and a subwoofer, the crossover is an important part of the package.

Passive crossovers tie into the wired connection between an amplifier and the speakers and block unwanted frequencies. Active or electronic crossovers stand between the receiver and the amplifier, where they can direct frequencies to the proper speakers before the amplification process. Active crossovers are more efficient because they handle the sound before it goes through the amplifier, and they're more customizable than passive crossovers [source: Crutchfield].

Picture your favorite way to listen to music. Is it at home, on a comfy couch, with a surround sound system? Is it at a computer with a pair of noise-cancelling headphones? As a general rule, it's nice to be able to hear music without interference from external sound. Cars produce quite a bit of noise, which can make them a less-than-ideal listening environment. That's where soundproofing comes in.

Unless you're driving a luxury car with an incredibly quiet interior, installing some simple soundproofing can help reduce engine noise. Less engine noise means a better listening experience. A popular choice is a sound deadening material called vinyl nitrile foam. Lining the car hood with soundproofing material will cut down on the rumble of the engine and make the car interior more peaceful [source: Nash].

Sound can sneak through the doors, too, but the same practice works there: Simply purchase a soundproofing kit and apply the material to the inside of the door to reduce road noise. Soundproofing.org details the process of lining a car hood with a piece of cut-out soundproofing foam and an adhesive to stick it to the hood of a car. Sites like Parts Express sell inexpensive sheets of foam soundproofing for less than $5. Another option is sound dampening foam. When it's sprayed in a door or some nook or cranny, it dampens vibrations and reduces unnecessary noise.

Nine down, one to go. What could be left for any car audio system? It's soundproofed, packed to the brim with speakers and amplifiers that are all tied to a powerful and flexible receiver. There's only one last step to take: enter into the realm of video.

If you're going for all-out luxury with your car's audio system, look no further than a DVD player. DVD players consist of several parts and are ideal for families with kids to entertain. One component of the DVD player is a receiver. The GPS receivers we mentioned earlier sometimes include DVD support, which makes sense; the GPS head units typically include a large screen that would work for DVD playback [source: Billmeier].

Backseat DVD systems are typically installed in the driver and passenger headrests. If you don't want to go out and buy a brand-new luxury car with an integrated DVD system, consider buying one that can mount on a headrest. Many companies even sell detachable headrests with the screens already installed.

Despite the luxury and expense of mobile DVD systems, we may not see them in cars for much longer. Portable devices like smart phones and tablets offer individuals their own screens to use for movies or games. But if you decide to go with an in-dash GPS or DVD receiver, your car audio system should be able to handle virtually any media you throw at it.