Car audio and stereo: how to choose the best new head unit

Choosing the best aftermarket head unit to replace your factory stereo can be very confusing, but these tips can help you review your options.

Before you begin searching for the perfect stereo, make sure you know what you already have. If your factory head unit is about two inches tall and seven inches wide, it is single DIN size. Single DIN is the size that most head units come in. If your old head unit is not single DIN size, you will either have to purchase an adapter to fit a single DIN head unit or buy a head unit specially made to fit in the oversized slot. Take this into consideration when you are browsing for your new stereo.

The most obvious thing to look for is the functionality of the head unit. All units will contain a radio, but many people want to be able to play media. Ask yourself how you will listen to music. Will you need a CD player or a tape deck? Are you planning on adding satellite radio in the future? Will you ever listen to an MP3 CD? Do you need an auxiliary port to plug in external music sources? Decide what capabilities you absolutely need, and what you can do without. Now you should have a basic idea of what you are looking for.


Unless your system contains external amplifiers, the power of the internal amp is vital. Power is measured in terms of watts, and there are generally two power measurements for any head unit. The first measurement, peak watts, is insignificant. It is the second measurement, RMS watts, that will determine the actual power of your stereo. In most cases, the powerful head units will have cleaner and louder sound, but it is also important that the head unit does not produce more power than your speakers can handle. If you have any questions about this, be sure to ask around where you buy the unit, because blown speakers can get expensive.

Next, consider whether you plan on making future upgrades to your system in the future. If you plan on adding external amplifiers, try to find a head unit with pre-amp out jacks. These will make the connection much easier when the time comes. There are varying power levels for the pre-out jacks, ranging from 2-10 volts. Generally speaking, the higher the voltage the cleaner the sound will be, but don’t go overboard on 8 volt pre-outs if you do not plan on putting a high quality amp on the other end. Also, look at the number of pre-out jacks. Two jacks means you can amplify one set of speakers, four jacks can amplify all four speakers, and a fifth jack will allow the addition of a subwoofer. Again, be realistic; there is no point in paying for jacks that you will not use.

One area that you should not shy away from dropping cash on are the security features, especially if you live in an urban area. There are many different theft deterrent devices available, the most basic of which is the removable faceplate. This will allow you to take the faceplate with you when you leave the car, rendering the stereo useless to potential thieves. If you are prone to losing things, a better choice might be a stealth face, which simply turns into a black face when you turn off the car, giving the appearance that the stereo is non-functional. In high-theft areas, consider a stereo with a built in alarm that goes off when someone tries to remove the unit. Whatever you do, be sure your investment is protected.

Another thing to consider when choosing a head unit is the sound controls. Unless you have an external equalizer you will probably be using the built-in EQ settings. You will be better able to customize the sound of your stereo if you choose a unit with many equalizer bands. If simplicity is your thing, look for easy to use treble and bass controls. Also, if you listen to a lot of bass-heavy rap or rock, look for a bass boost function. Controlling the sound your stereo makes can be as simple or as complex as you want it to be.

Before you make the final decision on your new head unit, always remember to look at the controls. Are the buttons laid out in a logical way? It is important that you are able to find the controls without taking your eyes off the road. Be sure that the menus and settings are easy to find. Make sure that the buttons do not feel cheap and easily breakable. Finally, check out the looks of the unit. The display should be big and easy to read at a glance. Also, if you care about the fit and trim of your car, try to find a unit that will match the interior.

Go with the unit that feels right to you. This will be the piece of your stereo that you interact with on a daily basis. It needs to fit the specs you have decided upon, but ultimately picking the perfect head unit comes down to personal taste. If you have to sacrifice a bit of power to get a unit you really like, that’s fine. In the end you will be happier with your choice.

Car audio and speakers: how to install an amp

A basic guide to selecting and installing an amplifier for your car stereo.

Adding an amplifier to a preexisting head unit is probably your best bet to pump up the volume and clarity of your car’s sound system. You can install an amp whether your radio is old or new, and best of all: it is a relatively easy process.

Before you begin, check the back of your head unit for pre-amp outs. These are RCA stereo connections that should come in pairs. If you do not have pre-amp capability (no RCA out jacks), then make sure that the amp you choose is able to accept speaker, or line-level connections. In addition, make sure that the rated RMS power of the amp is less than or equal to the RMS power of the speakers you plan to connect it to. When you buy the amp, be sure to buy a power connection set and a patch cord to match—a salesperson should be able to help you with this.


Now that you have the amp, the first step is to choose a location inside your car to mount it. Typically, this means in the trunk, but it is possible to put it in the cabin if you have enough room. Be careful not to choose a location that will expose the amp or wires to direct heat, and be sure that the amp will not be covered by carpet. Your amp will get hot in the course of use, and it is essential that it has enough space for air to circulate over and around it.

Once the amp is secured in a good location, it is time to start wiring. Before you even think about where to run the wires, disconnect the negative terminal of your battery. Speaking of the battery, this would be a good time to take out the power connection kit and connect the long, (in most cases) red wire to the positive terminal of your battery. If you do not see an easy way to do this, it might be a good idea to invest in some inexpensive gold-plated terminals that will allow multiple connections from your positive terminal. Once the positive wire is connected directly to the battery, run it back toward the cabin of the car. Once again, avoid sources of heat, and try to keep the cable away from places that are likely to be splashed by water from the tires. If the cable already has a fuse on it, make sure the fuse stays in the engine compartment.

If the fuse came separately from the main power cable, you are going to have to cut the cable and patch the fuse in using crimps or a soldering gun. Make sure to use the heat-shrink tubing that probably came with the kit to seal off the connection so that water does not get inside. Now you should be able to run the rest of the cable through the firewall. Make sure to use a rubber grommet if there is any chance the insulated wiring might rub on sharp metal. Once inside the car, run the cable underneath the carpeting and back to wherever you have put your amp.

You can now connect both the long positive cable and the short negative cable to the amp. Find a grounding point within range of the negative cable. If none is available, you can make one by drilling a hole in the floor panel/chassis (be absolutely certain about what lies beneath) and using a nut and bolt to connect the ground wire directly to bare metal. If you can, scrape paint off of the metal before you connect it. Make sure you have a good ground, as this will directly affect the quality of your sound. At this point the amp is wired for power. Now it is time for the sound.

If you are using the RCA pre-outs this is as simple as running a patch cable from the back of the head unit to the amp. If you are using a line-level connection, you need to run speaker wire from the outputs on the back of the head unit to the amp. A tip: if you are hooking up your rear speakers and your amp is in the trunk, you can just use the wires that are already there. This is a simple matter of moving them or lengthening them so that they will reach the amp. Whether you are using a line-level or RCA connection, plan the paths of the sound wires so that they do not run parallel to the power wires. It is best to run power wires on one side of the car, and sound wires on the other. Remember to run the remote amp control (if your head unit or amp supports this) at the same time as the sound wires. Because this wire carries very low current, it shouldn’t be a problem if it is parallel to the sound wires.

Finally, run speaker wire of 16 gauge or less from the speaker outputs on the amp to each speaker you wish to power. Connect the speakers, paying attention to the polarity. Now fire up the stereo and test everything out. Sound alright? If you hear distortion, it is probably caused by interference with the sound wires, so make some adjustments to get the best sound quality. If you hear your engine through your speakers as you rev it, this is caused by a bad ground. Once everything sounds good, set the gain control on the amp so that all of your speakers sound even and balanced. Enjoy your new amp!