Car Audio Buying Guide

Car audio buying tips

What kind of listener are you? Do you just want a good sound while driving to work, or do you want astounding sound because you live in your car? Choose your car stereo system (and its cost) based on what you want out of it. If good is good enough, buy some simple 6x9 car speakers and a stereo receiver and you're done. If it has to be the best, spend what you need and don't worry about the price. (Of course, at Overstock.com, you never need to worry about the price.)

You can read Overstock.com's audio buying guide for more complete information on the tech-speak involved in choosing a quality car stereo, but your first concern is simple: do the components match? Electricity is like cooking -- almost any ingredients, mixed properly, can turn out good eating, while the best ingredients, mixed improperly, get you dog food. You'll see two important ratings on every car stereo systems component--power and impedance.

• Power: The amount of electricity each speaker can use before exploding (okay, before being damaged). Measured in watts (W), most components carry two numbers: normal and maximum power (which is almost always twice normal). For example, a component is marked "75W RMS/150W peak power" or "75W continuous/150W peak". RMS is "root-mean-square;" a meaningless phrase unless you're an engineer, except that it describes steady power use. Peak is the maximum safe load. Think of wind -- RMS is a breeze, peak is a gust; too much and your audio speakers will look like the first two little pigs after the big, bad wolf got done with them!
• Impedance: Wires and microchips are solid objects, so they impede (ever so slightly) the flow of electricity. Think of a water pump connected to two pipes -- the larger pipe has lower impedance because more water can flow through. Measured in ohms (abbreviated by omega, that horseshoe-looking Greek letter), stereo amplifiers and speakers are usually rated at 4, 8 or 16Ohms; they work best when numbers match; mismatched components can give you bad sound or damage each other.

Having decided on your car audio goal, let's kick the tires:

• Price: Even at Overstock.com's clearance-sale-every-day-prices, you can spend a lot of money on car audio (we know, it's hard to believe, but it is possible). You can buy a discount car audio system (but never cheap car audio) or the most expensive car stereo system with all the bells and whistles. Before you begin, set a budget; then pick the components that fit your budget.
• Scope: If you don't care about bells and whistles, pick up a basic car radio, car amplifier (car amp, for short), a car CD player and car stereo speakers and you are good to go. If you want all the toys, you can add a satellite radio, a car CD changer or portable DVD player (or both), subwoofers, big auto speakers in big speaker boxes--as much for show-off as for show tunes--the list is as long as the line at the DMV.
• Priorities: Now that you have an audio system in mind, make a list of the audio equipment that fits your budget and rank the features: How many speakers? Are you replacing the OEM or adding to them? Do they fit under the seats or will they be trunk-mounted? DIY or shop installation (an added expense)? The more questions you ask, the more you'll know exactly what to buy.

And, the more you buy, the more you'll save; just think of Overstock.com as your personal "Penny Lane."

Car audio components

"Car stereo" (also called car receivers, stereo receivers or in-dash tuners) used to mean a radio and a pair of speakers. Now it means a multimedia entertainment center. Audio receivers are the heart of car audio systems. Car stereos include AM/FM radios--often they are clock-radios; some have built-in equalizers; car CD players are also common. The newest feature is iPod or MP3 player compatibility, allowing you to mate your portable audio to your car audio. By the way, there are a lot of digital audio formats out there; make sure your new audio receiver is compatible with all of them, or, at least, the ones you intend to use:

• CD, CD-R, CD-RW, MIDI, MP3, MPEG4, WAV, WMA
• VCD, DVD, DVD-R, DVD+R, DVD-RW, DVD+RW, DIVX (if you're adding a car DVD player)

The front (called the interface or face-plate) should have volume, bass and treble controls; a small built-in equalizer is great for customizing the sound. On a really good system, the face-plate is removable as a security measure. The most common car audio components are:

Amplifiers

If your car audio amplifier and speakers are rated at 20W and you want to add another pair of 20W speakers, you need more power--a new car amp--to drive those speakers. Modern microphones are so efficient that they use only a trickle of electricity; a car audio amplifier can turn that trickle into a flood. Car amps read electrical signals and reproduce them at higher power. When matching your car amp to your speakers, double the power and equal the impedance. For example, if you buy a 20W RMS/4Ohm speaker, you want a 40W/4Ohm car amplifier. For multiple speakers, you'd want 40W per channel.

CD players

You can get a single-disc CD player in your in-dash unit or add on multi-disc CD changers. A car CD changer is great because you can load up 6 or 8 or whatever number of discs; hit the gas and never hassle with changing the CD.

Equalizers

An equalizer (or audio signal processor) fine-tunes the car sound system by boosting the volume on some frequencies and "limiting," frequencies you don't want to hear. Equalizers divide the audible spectrum into "bands" and are commonly found in 3-band, 5-band and 7-band models, although 15-band equalizers are available. These are pricey, but, hey, you're worth it!

Inverters

A power inverter changes DC power to AC power; it's that simple. Most components in car sound systems were designed for automobiles, so they run on DC power. If you want to plug in an AC-powered unit--you can't, the plugs are different. You'll need to plug the AC device into a power inverter then plug the power inverter into your car's power. If you think you'll be using power inverters frequently, you might as well get a multi-socket inverter hard-wired to your battery. If it'll just be used occasionally, an inverter that plugs into your cigarette lighter is fine. Of course, portable music players and cell phones often have lighter plugs, so if you use them a lot in the car and still want an AC outlet, the hard-wire idea is the way to go.

iPods and MP3 Players

These wonders provide, for many, ultimate audio freedom--go almost anywhere, use almost anytime. Docks for these mobile units are available for home theater and car audio systems, allowing you to play your digital music through your home or car stereo. Many iPods and MP3 players are integrated with cell phones, PDAs and other consumer electronics, which can also plug into and operate through your car stereo equipment.

So, it won't matter "How Many Roads" you have to drive or if you are "Off the Road" for a while; Overstock.com's affordable portable audio will keep the music playing "24 Hours at a Time".

Satellite radio

Car radios are standard equipment, but some people want more. Satellite radio differs from broadcast radio in two ways: The signal is propagated from a geosynchronous satellite, so it can be received almost anywhere in the United States, and satellite service providers earn revenue from subscriptions instead of advertisements. If you live in a small market with just a few stations, a satellite receiver is an investment worth making.

Speakers

Every auto maker puts a good car speaker in their vehicles, but many people want something better, making speakers among the most popular automotive upgrades. You can buy speakers unpowered or go for powered speakers, which have a small amplifier built in. That's the easy way for beginners. Also, for novice do-it-yourselfers, "drop-in" speakers are good -- they match the cut-outs the factory made for the original equipment. Now you must decide on the speakers themselves:

• Coaxial speakers combine the woofer and tweeter.
• Component speakers are separate woofer and tweeter pairs; they can be mounted individually to give the best sound in your specific car.
• Subwoofers, also called car subs, are necessary to the audiophile because most auto speakers are too small for really good bass.

Now that you have the car sound system of your dreams, you'll never again drive those "Lonesome Roads"--you'll always have plenty of musical company.

Car audio terminology

DIN v. Double DIN: Refers to the size of the front face of an in-dash unit. They were first created by the German standards organization Deutsches Institut für Normung becoming known as the "DIN car radio size." They were adopted internationally in 1984. Since a faceplate can overlap the hole in the dashboard, a given unit might be a little taller or wider than DIN specifications:

• DIN: 180mm x 50mm or 7 inches x 2 inches
• Double DIN: 180mm x 100mm or 7 inches x 4 inches
• Depth is not standardized, so you might want to measure to see how far you can go.

Frequency response of human ears ranges from about 20 Hertz to 20,000 Hertz (20Hz-20KHz). No speaker can do it all, so several types were developed:

• Tweeters: can get up to 20KHz
• Mid-ranges: reproduce 500Hz-3KHz
• Woofers: reach 500-200Hz
• Subwoofers: go deep, close to 20Hz

Sensitivity measures speaker efficiency, or how much volume a speaker puts out for a given voltage. Simply put, if speaker A's sensitivity is rated 3dB higher than speaker B's, then A needs less juice to put out the same volume as B. That means nothing to the performance, but it could mean something to your pocketbook.

Signal-to-noise ratio (SNR or S/N) is about clarity. "Signal" is the sound you want to hear; "noise" is the audio clutter in the background. Usually measured in decibels (dB), the higher the ratio, the less noticeable the clutter.

Total harmonic distortion (THD) is similar to SNR. Imagine an amplifier as a copier set to enlarge; it won't make a perfect copy. These imperfections are "distortion." THD is expressed as the percentage of distortion within the total sound. A good audio component has a THD around 1 percent; really good audio components are below 0.1 percent.

Car audio care

Audio systems don't require much care. Very few have moving parts that can break, though dust, heat and humidity are problems. Wipe down the exteriors regularly, buy a can of air and blow clean the openings, air vents, CD & DVD slots, etc. Never blow them clean yourself; the humidity in your breath is not good for them.

Electronics will wear out eventually, but you can extend their service life by not abusing them. Electricity flow generates heat, so be sure the components get proper ventilation, especially since most car electronics are in a tightly enclosed space--dashboard, trunk, etc.

"Heads" are the components that actually read the CDs, DVDs and so on. These need to be cleaned periodically, and many kits are commercially available. They are inexpensive, quick to use and give you better output when used regularly.

With just a little effort on your part, your car sound system will be at its best, whether you're in a "New York State of Mind," crossing the "Arizona State Line" or driving "North to Alaska."

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