Nothing says “the open road” like having the right music when you’re driving. Whether it’s listening to podcasts on your morning commute or putting together the perfect playlist for your next road trip, your car’s radio is an important part of the experience. A lot of drivers may not even consider the stereo system in their vehicle until it fails, while some audiophiles may demand the very best in volume and clarity for their ride. In this article, we’ll try to not only help you understand what to consider when shopping for replacement audio and infotainment equipment for your vehicle, but also how to easily install most car stereos using only what you might already have in your toolbox.
There are a few factors that should be considered when looking for the stereo or entertainment system that best suits your needs. Though this may not be a complete list, it is a good place to start, especially if you’re new to the world of car audio.
How Do You Use Your Car Stereo?
This one is pretty self-explanatory, but how do you use it? Is it mostly for noise while you drive, or do you prefer high-quality audio? Do you like control over equalization, and outputs for a separate amplifier or subwoofer? All of these factors can affect your decision-making when you’re shopping for a new head unit or other accessories for your vehicle.
What Type of Media Do You Play?
Do you take your CD collection everywhere with you, or are you more likely to listen to music in your favorite phone app, or even from a flash drive? Most modern car stereos have built-in auxiliary inputs, but if you want to use the Bluetooth off your phone, other adapters may be needed if your stereo isn’t set up for it. Digital media receivers are more common now than ever, and they are designed only for auxiliary input, or loading media from a USB flash drive or SD card. This means that your CD collection would start collecting dust. Some people even prefer an infotainment system that can also play DVDs or digital video media, or that can display GPS mapping or directions from their phone, so be sure that the media that you use most often is supported by your stereo.
How Loud Do You Like It?
If you’re upgrading your car stereo, it could be for a number of reasons, but the most common is power. Factory stereo systems can sometimes be a little lackluster to those that like it good and loud, and ensuring that your new stereo system has the power you want is crucial to your decision. When considering your stereo purchase, be sure to pay attention to RMS (root mean square) wattage, as this is the amount of continuous power output your stereo can produce (per channel) without distortion or damage. If your new stereo still doesn’t have the output you desire, you can always add an amplifier to the system as well.
How Much Space Is Available on Your Dash?
It may seem obvious, but you have to be sure your new stereo will actually fit in the space you have in your car. Car stereos are usually available in single- or double-DIN sizes. This simply refers to the size of the stereo chassis, and a single DIN stereo will be two inches tall by seven inches wide, while a double-DIN stereo is four by seven inches. Even if you have room for a double-DIN, either option may require an adapter to fit the factory opening. If that is the case, a single-DIN adapter for a larger opening may also include a storage tray or filler panel.
What Car Stereo Features Do You Need or Want?
Do you need to be able to run an amplifier or control a subwoofer independently from the rest of the volume settings? How much equalization control do you require? Do you want to customize the color or illumination brightness of the display? What about Bluetooth, SD cards, or other types of media? Being sure what you need before you shop for a new car stereo can help you be sure you won’t be disappointed after installation.
What is Your Budget?
You can spend about as much or as little on a new car stereo as you want, and getting what you pay for is certainly a factor. Stereo systems are relatively inexpensive compared to a lot of the other upgrades you can make to your car, but having an idea of what you’re willing and able to spend on your upgrade will simplify the shopping process. Don’t forget to factor in the cost of wiring and installation adapters, upgraded speakers, or dash plates to fit your new stereo to your vehicle.
How to Install a Car Stereo
When it comes to installation, it’s always tempting to leave it to the professionals. Before you start searching “car stereo installation near me”, continue reading to see just how simple it can be to install an aftermarket car stereo system. With basic tools and a little bit of electrical system knowledge, you can save a significant amount of money on installing your new car stereo.
In the case of most modern vehicles, installing a stereo may be even simpler using an adapter kit that doesn't require any permanent wiring modification, and your new stereo installation may be nearly plug-and-play. If you are unable to find the appropriate car stereo adapter kit for your new stereo, the process is slightly more complicated, but is a very common DIY modification that requires a little bit of know-how and a few tools.
Installing a Car Stereo with an Adapter Kit
Using an adapter kit to install an aftermarket car stereo is often the safest and most straightforward approach to your upgrade. Adapter kits include the OE-style wiring connector on one end to connect to your vehicle’s existing wiring harness, and may have the correct connector at the other end for the new stereo. In other cases, they may only have the vehicle-side connector and color-coded wires to be connected to the plug supplied with your new stereo unit. If you have the right connectors at both ends, you can simply plug in the new car stereo and you may be done. If connecting the adapter to the new stereo wiring is necessary, you can simply trace and line up the appropriate wires and make your connections using a wire crimping tool and butt splices or butt connectors. These connectors slide over the bare end of the wire and are crimped in place to connect the wires together. You can learn more about how to install and crimp wiring connectors with our helpful article.
Using the appropriate adapters to install your new car stereo is beneficial in several ways. First, it doesn’t require you to trace wires to determine what each one does and where it should be connected to your new wiring harness. The plug-and-play installation also means that if you wanted to put your original radio back in the vehicle, this could be done very easily. Finally, a number of newer vehicles use the radio to play system messages or for the alerts or indicators caused by seat belts, turn signals, Check Engine lights, and more. If an appropriate chime module or wiring adapter is not included in your installation, you may lose this functionality. It may also be necessary to purchase an adapter specifically for the steering wheel controls or rear entertainment system controls, so be sure to take a full inventory of the features already included on your vehicle and be sure that your stereo and adapters can support these functions.
Hard-Wiring a Car Stereo
If you drive an older vehicle, or if your car does not have an available adapter kit, it may be necessary to hard-wire your new car stereo into the existing wiring harness. Hard-wiring involves cutting or tapping into existing wiring under your dash, or even running completely new wiring to power the stereo. This may be necessary in vehicles which never had a radio originally, or instances where a previous owner has significantly damaged or removed under-dash wiring that was intended for the stereo system.
The first step when hard-wiring your car stereo is to find a source of power and ground. This is most easily done with a wiring diagram for your vehicle, but you can also do so using a test light or a multimeter. A test light is simply connected to a good ground and lights up when it contacts a power source, whereas a multimeter will read voltage using both a power and ground probe. You can learn more about using a multimeter with this helpful article. Your vehicle’s under-dash wiring often has two kinds of powered wiring, and your stereo will require both to operate correctly. You will need both a continuous power source, or a wire that has 12 volts whether the key is turned on or not, and a switched or accessory source, which only has 12 volts when the key is in the “Run” or “Accessory” position. The continuous power source allows you to save presets to your new car stereo, and without it, you will have to start over with your preferred radio stations and audio settings every time you turn your vehicle on. The switched power source turns the stereo on and off with the key, and is necessary to prevent having to turn on or power off your radio separately from the rest of the vehicle.
After you’ve found your switched and continuous power sources, you will need to locate a suitable ground. Ground wires in automotive electrical systems are typically black, and are often connected directly to a metal surface under the dash. This allows the circuit to complete and travel back to the ground wire of the battery. If you can’t find usable ground wire under your dash, it’s also possible to add a grounding wire to a grounded metal surface. Many installers will do this using a wire, a ring connector, and a self-tapping screw. You can also test for ground by connecting your test light to your 12-volt power source and then probing wires or potential grounding surfaces until the test light illuminates. If you'd like to learn more about how to install and crimp wiring connectors, check out our How-To article.
Once power and ground have been addressed, you can begin connecting the remaining wires from your new stereo wiring. These typically include eight speaker wires, one hot and one ground per speaker in four-channel stereo systems, as well as optional connections like a power antenna control wire, illumination or backlighting control, amplifier remote turn-on, and even wires for connecting to existing steering wheel or external radio controls. These wires may not need to be hooked up if you do not have any of these accessories, and can simply be capped or taped to prevent them from shorting out against any ground points under the dash.
If you have your switched and constant power source, ground, and speaker wires connected, the final step is to connect the radio antenna. Older antenna connectors are relatively universal, and most modern replacement car stereos will still accept this type of antenna connection. If your vehicle has a proprietary antenna connection that does not match your new head unit, it may be necessary to install an antenna adapter to secure the connection. At this point, you should be ready to reconnect your battery and test the stereo to ensure that it powers on and that all of the speakers are working as they should. If the unit doesn’t power on it, it may be necessary to check the appropriate fuse, the wiring connections, and the ground or power supplies to ensure it is receiving the power needed to turn on.
What About Car Speakers?
Installing a new car stereo can be a drastic improvement over the original radio in your vehicle in both power and clarity, but if you’re still using the vehicle’s original speakers, you may be less than impressed with your upgrade. Many factory speakers are built using relatively cheap materials, including cardboard, and may only have a single driver element which is responsible for all the frequencies coming from the stereo. Upgraded aftermarket speakers are often coaxial, meaning that they not only have the single speaker cone featured in factory speakers, but also have a second speaker or tweeter and a crossover. An internal crossover allows the incoming signal to be split appropriately to improve the frequency response of both the woofer (the lower speaker) and the tweeter (the upper speaker).
Another type of coaxial speaker, called a 3-way or 4-way speaker, may have one, two, or more tweeters and an internal crossover. These speakers are designed to provide the best possible response across the entire frequency spectrum, and offer more clarity than factory single-cone or upgraded 2-way coaxial speakers. They are also typically more expensive, but depending on the clarity, depth, and price you’re willing to accept, may be the best choice for your upgrade. Component speaker systems are also available to separate one or more tweeters from the cone and install them elsewhere in the vehicle. These often require an external crossover, and necessitate more complicated installation and wiring.
Another type of speaker you are likely familiar with is the subwoofer. Subwoofers are designed to respond to the lowest of all low frequencies found in music, and are typically much larger than the speakers found in your vehicle from the factory. Subwoofers are usually installed in a self-contained enclosure since most vehicles do not offer an appropriate location for installation from the factory.
How to Wire Car Speakers
Speakers are relatively straightforward to install, but much like aftermarket car stereos, the original wiring and equipment on the vehicle may dictate the appropriate installation method. Aftermarket car speakers will have two spade connections for the positive and negative speaker wires, and typically they are two different sizes to prevent reversing the speaker’s polarity. The positive terminal will usually be the larger or the two, but most speakers are also marked to prevent confusion.
Once you have determined the layout of your speaker terminals, you will also need to inspect the speaker wiring currently in your vehicle. If you’re replacing factory-original speakers, they may have a special connector instead of blade or spade terminals. If this is the case, you can remove the original speaker by disengaging the tabs on the speaker connector. From here, the easiest installation method would be to find the appropriate speaker wire adapter to plug into the original connector, as these adapters will also have the appropriate blade connectors for your aftermarket speaker. This also allows the original speakers to be reinstalled if you wish. You can also cut the connector if you so choose and crimp on blade terminals, ensuring that you determine which wire is positive and which is negative.
In some cases, especially if you are installing larger or differently-shaped speakers than what came from the factory, you may also need to modify the way that they are mounted. This can include cutting the panel, drilling new mounting holes, or installing threaded clips for new screws. Aftermarket speakers usually also include templates for cutting and drilling holes to fit the speakers, but be sure to map out your plan before breaking out the drill or saw to be sure your speaker will have plenty of room and not be in the way. Also ensuring that the speaker is very securely installed and screwed in tight can help reduce the risk of rattling while driving or playing music.
Amplifiers, Subwoofers, and Other Car Audio
While a simple replacement head unit and upgraded speakers is plenty for most drivers, others may want to go further with their car audio. Amplifiers allow for more RMS power than most aftermarket stereos can deliver on their own, and can support a single channel for a subwoofer or multiple channels to power all of the speakers in your vehicle. Most modern car stereos have one or more sets of RCA outputs and automatic amplifier turn-on wires integrated into their design, and this can make adding an amplifier to the car very simple. An amplifier will require a dedicated power source and ground using heavy-gauge wire, so it’s important that you get the correct supplies together before attempting to install it.
Subwoofers are typically passive speakers that require a separate amplifier for power, as automotive stereos typically do not have a dedicated subwoofer power out. Powered subwoofers are also available, which include an amplifier and subwoofer in one assembly. External crossovers may also be necessary to filter the incoming signal to be sent to a subwoofer, tweeter, or midrange speaker and ensure every part of the audio system is only receiving the signals for which it is responsible and best-suited.
If you’re ready to upgrade your car’s stereo system, or are simply looking for an aftermarket replacement for a non-working radio or blown speaker, check out the selection of car stereo and car speaker products at O’Reilly Auto Parts. We also carry adapter and installation kits, speaker wire, car antennas, and more to help you make your repair or upgrade. If you’re not comfortable performing these upgrades yourself, we can also recommend a local shop that specializes in automotive electronics repair or installation.