Overview

    Welcome to the world of Car Audio.  The purpose of this guide is to familiarize you a little with the basic workings of car audio.  The next few pages will explain briefly the inner workings of the most common components of an autosound system:  The Head Unit, the Amplifier, the Subwoofer, and the Speakers.  The other pages will touch on basic installation of these components.  We hope that you find these pages useful, and would appreciate any comments that you may have.  (Insert e-mail address here)

Source Unit

    The Source Unit is usually the first part of any car audio installation no matter how basic the install.  The head unit is the source of all audio signals for the entire system.   For most installs, even higher end ones, pretty much any Source unit will work well.  Look for ones with higher Voltage though for the most accurate signal to the amps!  A good initial signal is vital for all sound reproduction!  And yes, this can be noticeable from Unit to unit!

Amplifiers

    An Amplifier is a device that takes an input signal, (from the preamp) and produces a higher level output.  An amplifier is essential if you are planning to run a subwoofer.  This is also an important part of the install for sound reproduction!  Choose your amps wisely for the most accurate sound available!

Subwoofers

     A Subwoofer is the part of the audio system the creates the low end or bass frequencies.  Subwoofers range come in a variety of sizes and must be driven with an amplifier

Speakers

    The other speakers in the car audio system are used to create the mid and high level frequencies.  The two major types of speakers are components and coaxials.

Installing A Head Unit

Fortunately, most units follow the same size standards (DIN).   In many cars, once the factory radio is removed the aftermarket radio will fit in the hole.  In many other cars, a kit is needed if the factory hole is too big, or not deep enough.  In some cases the dash has to be cut.  Any car stereo store should have kits required for installation.

Even though not necessary, it is recommended to use a wiring harness when installing an aftermarket radio.  The harness is wired up to the radio, an plugs directly in the factory plug, making a good and easy connection.  Since the factory plugs are not cut, the manufacturer's warranty is not voided on the vehicle, and the factory radio can be reinstalled when it is time to sell the car.
  

Radio Mounting

Aftermarket radios can mainly be mounted in two ways:

ISO mounting is when the radio can be screwed to existing factory radio brackets, such as in most Japanese cars.

Ring mounting: Most aftermarket radios come with a metal ring that gets mounted to the factory radio hole or aftermarket kit via bendable tabs.  In many cars, dash and trim rings have to be filed to enlarge the radio hole.   Once the ring is installed, the radio slides in and is held by snaps.  In most cases, special tools are required to remove the radio.

Using the Factory Head Unit

Adding amplifiers to factory head units or head units without RCA outputs can be easily achieved with a high-level to low level adapter.  The adapter reduces the level of the signal coming from the head unit's speaker outputs to lower levels that are acceptable for amplifier inputs.  Some amplifiers have this adapter built in for convenience.  The drawback of using speaker outputs is that the signal is not as clear as it would be coming straight from a set of RCA wires.  If the factory unit has distortion on the output, the distortion will be passed along to the amplifier.

Replacing the Factory Head Unit

Many cars with high-end factory systems such as Volkswagen's Atkiv Speakers, GM's Delco-Bose, etc. have amplifiers that require an interface kit to match signal levels, or are best completely rewired.  These kits are usually expensive.   To bypass amplified speakers sometimes existing wiring can be used.  In other cases wires have to be run to each speaker.  Factory amplifiers such as in some Fords use a 5-volt turn on wire instead of the usual 12v.  Even though factory amplifiers can be hooked up to aftermarket radios directly, they can be prone to noise.   Consult a professional before tackling one of these projects.

Getting Better AM/FM Reception

Believe it or not, factory tuners are usually better than aftermarket units.  The most important part of the tuner is definitely the antenna.  If you have a bad or broken antenna, you tuner will not pick up the stations as it should.  If the antenna has to be replaced or upgraded, make sure it is the same length as the original.  The length of the antenna greatly affects reception.  Lower frequencies (AM) are best caught with a long antenna, while higher frequencies (FM) need a shorter antenna.   Car manufacturers compromise a bit, giving you a length that would work best while receiving both AM and FM frequencies.  If you get a short antenna, such as the 1 foot rubber antennas, the FM reception will be poor and AM will be almost non-existent.

Troubleshooting: If you have poor reception, do this simple test:  Try a couple FM stations and a couple AM stations.  If you have no AM at all, but you get FM, then the problem is most likely the antenna.  If your radio can't get neither, then the problem is either a broken or disconnected cable or a bad tuner.  Plug a test antenna to the radio to make sure the problem is not the radio itself.

Seat and Panel Removal

If you are working on you car stereo or security system, you will most likely have to remove some panels, consoles, trim rings, etc. Factory panels are not always easy to remove. If you break a panel, you will regret not being careful. Dealers charge a fortune for parts.

Before you even think about pulling on a panel, make sure all the screws and other fasteners have been removed. If you can't figure out how to take a panel out, get help. Borrow a manual for your car at the library, ask a car stereo shop in your area or ask a local car dealer.

If the car is out in the cold, panels tend to get hard and brittle, and may break easily, particularly in old cars. Try heating the panel(s) up before you remove them with a hair dryer or heat gun.
  

Most panels are mainly held in place by screws, snaps, other panels that overlap them, and any combination of the three:

Radio Trim Rings

To make cars cosmetically appealing, manufacturers hide screws behind "dummy plates" and electronic controls. In many cars you have to pull out clocks, hazard light switches, defroster controls, etc., to get to the screws that hold the panel. If you need to remove a switch or instrument in a panel, don't just insert a flat screwdriver on the side and pry. This will bend and scratch the panel. Try pulling the desired part with a hook. If you have no other option than to pry, place a cloth on the screwdriver to prevents scratches.

Many radio trim rings use snaps, either by themselves, or in combination with screws. Double check to make sure you did not miss any screws. Pull evenly on the panel, either using a panel removal tool, or a hook. If the piece is too tight, there might be a screw somewhere you might have left out. In many cases, such as most Hondas, you don't even need to take the trim ring out at all to get to the radio, just remove a couple screws that hold the radio from behind.

Consoles

Relatively easy to remove. Ninety-nine percent are held in place by bolts and/or screws. First, take all the stuff out of pockets, boxes, compartments, ashtrays, etc. Remove all visible screws. If the console does not pull out, search for hidden screws. Many cars (especially European) use a piece of carpet to cover up screws. Cars such as Mercedes Benz have screws hidden under the ashtray. The parking brake is a common obstacle. In some cars you might have to slide the front seats all the way back and recline them to get the console out.

Dashes

Some people remove the whole dash to hide alarm components, and access electronic devices in the car. These people are experienced. Removing a whole dash takes many hours and patience. If you are not careful when reinstalling the dash, wires might get pinched and you might smoke something. Remember that the electronics around the dash control the main functions in your car, so you can't never be too careful here. Most cars have a clip that has to be pulled out in order to remove the speedometer cable from the instrument panel. Before you take anything apart, unhook the car's battery (this is good practice when you are working on your car in general). Find hidden screws and bolts by "peeling" off panels. Unhook electronic components and harnesses as you go along. Mark things if necessary for reassembly.

Seats

Most front seats are held by bolts and nuts. Some cars have extra brackets or seatbelt anchors that must also be removed. Many newer models have pieces of plastic or carpet over nuts and/or bolts holding the seats for cosmetic reasons. These pieces can be easily removed using a panel removal tool, or taking screws out (if they have any). Before you pull the seat out, be careful to unhook any wires plugged up to the seat, and take extreme care not to scratch anything while you take the seats out of the car. To make life a bit easier when remounting the seat, first slide the seat all the way up, remove the bolts on the back. Slide the seat all the way back, make sure the seat is locked in position, and then remove the remaining bolts at the front.

Rear seats are fastened in many different ways. On most cars, the base part of the seat is held in place by a metal snap going into a hole. To remove, pull on the front of the seat. Some cars have a metal or plastic tab that has to be pulled, pushed, or moved to the side, while pulling on the front of the seat. Other cars, mainly German, use bolts or screws in the front to hold the base of the seat. Many American car seats (GM) have a hook that fits into a metal brace. To remove the bottom part of the seat push hard towards the back and then up. Most Hondas use a bolt (10MM) on the back part of the seat between the bottom part of the seat and the back support (towards the middle) that has to be removed. Then the seat can be pulled up from the back. Before you pull on a seat, try to analyze what is holding it. Most seats do not need a lot of force to be removed, they all have a trick.

The back support on the rear seat is a bit more standard in the way it is fastened. At the top, there are 2, 3 or 4 pieces of metal that go into a hole. There are 2 or more bolts that hold the backrest at the bottom. Once you have removed the bottom part of the seat, take the screws or bolts out, and slide the back rest up and out. On a few cars you have to remove the rear deck and other side panels out first. If you can't figure it out, remove the panels in the other side of the backrest (trunk) and examine carefully how the seat is fastened.

Door Panels

A bit harder to remove than the rest of the panels in a car because they house window cranks, buttons, mirror controls, speakers, etc. Some cars even have seatbelts built in the doors. The first step is to remove all the screws on plain sight. Look for screws hidden behind speaker grilles, power window/lock/mirror controls, ashtrays, interior light covers, dummy plates, etc. Windows all the way down help a lot during removal and reinstallation.

If your car has manual windows, use a crank clip removal tool to get the clip out. Pull the crank out. Since clips holding the cranks are small and thin, they tend to fly away and get lost. Some cars (mostly VW) hold the crank in position with a bolt, hidden behind a plastic cover. Other cars (i.e. old AMC and Cherokees) use a crank that snaps in place. Once you have removed all the obstacles (in some cars such as Isuzu this even requires removing the speakers), try to see how the panel is ultimately held in place. There are two basic systems:

- Snaps (most cars, especially imports), which are best taken care of with a panel removal tool. Sometimes snaps break from the panel and stay on the car. Remove them from the door with a panel removal tool, and reattach the snaps to the door panel before reinstallation. Once you get everything loose, most panels need to be pulled out at the bottom and then up.

- Hooks (some Fords, i.e. Thunderbird and GM, i.e. Camaro), in which the panel has to be pulled up first and then out.

Rear Decks

Rear decks are not fun to take out. Most involve removing the back seat and backrest, side panels, seatbelts, speakers, etc.
The best way to remove a rear deck is to follow these guidelines: Remove snaps using a panel removal tool. Remove third brake light casing, if necessary. Remove other obstructions such as speaker grilles, speakers, seats, panels, seatbelts, etc.

Trunk Panels

Manufacturers do not take much time trying to hide screws and snaps on the trunk/hatch. That makes trunk panels fairly easy to remove. Most are held by snaps, screws, or a combination of both. Again, the procedure is to remove any visible screws and snaps. Search for hidden screws under dummy plates, access doors and light bulb covers. On some hatchbacks, speaker grilles, speakers, seatbelts, even the back seats need to be removed to clear the way for the panels to come out.

Kick Panels

Probably the easiest to remove, due to their small size. Most manufacturers use bolts and/or snaps. In some cases, such as old BMWs, the speaker grilles hold the kick panels. The most annoying obstruction is generally the hood latch popper.
  

Repairing broken panels

Even the pros break a panel or a snap every once in a while (professional installers are very good at repairing broken panels). If you cracked a panel, there might still be hope. A hot melt gun is a must have here.

Since most panels are made out of plastic, it is fairly easy to fix cracks and breaks. One of the best techniques is to cut a piece of metal from a paper clip, and dig it in the plastic for support. Here's how to do it: First place the panel to be fixed upside down on a flat surface (over a cloth, so that it does not get scratched). Cut a piece of metal from a paper clip (about an inch long or so). Place the piece over the crack (again, on the back side of the panel) and hold it in place with a flat screwdriver or pliers (NEVER with your fingers). Use a soldering gun to heat the metal, applying a bit of pressure so that the clip melts its way in the plastic as it gets hot. It is better if you start on one side, and then work your way to the other side of the crack, don't try do it all at once. Be very careful not to push the clip all the way through to the other side of the plastic, you don't want anything showing on the front side of the panel. It is highly recommended that you practice a couple times on a piece of scrap plastic before you attempt the actual panel. When you are done with the soldering gun, clean the tip with a wire brush. The left over burnt plastic will not let it hold solder very good.

Another technique, which can be used in addition to the one previously mentioned or by itself, is to use a hot glue gun and pieces of either plastic or wood: Prepare the panel in the same way as before, but instead of placing a clip over it, spread some hot melt over the area, then place a small piece of wood or plastic, and add some more hot melt. Let cool down a couple minutes, and add glue on top as many times as needed. Make sure that the panel will fit in the car before you do this. Hot glue can also be used to attach broken snaps, and to build custom panels.
If you do break a panel and can't fix it, try a junkyard before you go to a dealer.

Speaker Installation

Speaker installation is very critical for performance. Whether you spent $50 or $1000 on a set of speakers, if they are not properly installed, the sound will not be up to par.

What makes a good installation? Well, certainly mounting speakers in most factory locations, such as on the bottom of the doors pointing at your legs, are not acceptable. In this cases a new mounting location might need to be improvised.

Distance

The first thing to consider is distance. If the left speaker is only a couple feet away from your ears, while the right speaker is several feet away from you, then the sound will arrive at different times giving you poor sound. The left speaker will sound louder since it is closer.

The best solution is to figure out a location where the difference between the distance of the right speaker to your ears and left speaker (also known as path length difference), are minimal. This is where kick panels shine, making it the preferred location for many audiophiles and competitors alike.

The other solution, which can get expensive, depending on the gear you get, is delays. By adding a delay to the left speaker, the sound can be doctored to arrive from both sides at the same time. This is only a patch, and does not sound as well as equally spaced speakers, but is the second best alternative.

Multiple Speaker Placement

If you have a system with two or more speakers per side, you need to carefully try different locations to obtain the best possible sound in your car.

Let's take a 2-way system with a tweeter and woofer per side as an example. The woofers are mounted in the factory location at the bottom of the door. The tweeters are mounted high up on the front corner of the door panel. Looking at the speakers from the driver's seat, you can see that there are 4 speakers all aimed towards different orientations and all at a different distance to your ears. This interaction of sound waves at different frequencies arriving at your eras at different times seldom sounds good. The best thing to do is mount the woofer and tweeter on each side as close as possible to each other. This is also why kick panels are used so much these days.

Professional installers do use some tricks such as inverting the tweeters' polarity when mounted for example on top of the dash while the woofers are low. Achieving good sound with unconventional mounting schemes is very, very hard and is only achieved after plenty of time has been spent trying different configurations.

Aiming

Our ears can distinguish the direction of sound more easily at higher frequencies.  This means that aiming the mids, and most importantly, tweeters towards your ears play a critical role in sound imaging.  Midbases are not so critical, but should be also aimed towards the listener's ears if possible.

To figure out the best aiming angle involves many hours -even days- of work.  To start, try to aim the speakers towards the center of the car.  Play around with different angles until you obtain the best "sweet spot".

Subwoofers should be mounted up front for best sound. Since this is not possible in most cars, mounting subs in the back is not such a bad thing, since most people can't distinguish where bass comes from. If you have good midbases going down to 60 Hz or less and subs picking up the signal below 60 Hz, then the bass will seem to come from the front.

Enclosures

Everyone is aware that subwoofers need a properly designed enclosure to give top performance. How about midbases and mids? They also do sound much better if they are installed in enclosures. The best sounding and easier to build enclosure type for midbases and mids is sealed.

Mounting Speakers

If you are using speakers that fit into a factory location, make sure there are no gaps or holes.  Sometimes building a wood or fiberglass baffle helps reduce holes and gives you much better sound.  Always be careful when using power tools around speakers.  Warranties usually don't cover holes in speakers.

For unconventional speaker locations, sometimes metal has to be cut.   If you have the resources, plasma cutters and pneumatics tools work great.   For most mortals that do not have these tools, a pair of metal snips (left and right cut) will do the job.

Speaker and Sub Wiring

A trick that professional installers use to get more power out of amplifiers is to wire up speakers in different ways, playing with resistances to achieve a desired total impedance "seen" by the amplifier. Even though speakers are active loads (resistance changes with frequency), it is accepted to treat speakers as resistors with a fixed resistance value (usually 4 ohms).

By combining speakers in different ways, maximum amplifier output can be obtained.  For example if a 2-channel amplifier is rated to deliver a maximum output of 400 watts at 2 ohms mono (bridged), then by hooking up two 4 ohm subwoofers in parallel, the maximum

Parallel Resistance

People commonly hook up two or more speakers to the same channel out of an amplifier in parallel. This is achieved by hooking up the negative wire from the amp to all the negative connections of the speakers, and the positive to all the positive connections of the speakers. By doing this, the load seen by the amplifier is lower. For example, if two 4-ohm speakers are wired-up in parallel, then their total resistance will be half, or 2 ohms. If three speakers are wired up in parallel, and they all have the same resistance value, then the total load would be a third of the value of each speaker's resistance. Here's a formula to calculate parallel total resistance for two speakers:

For more than two speakers, use the following formula:

So what are the advantages and disadvantages of this scheme? First, if one of the speakers burns out, then the other one(s) keep playing. If the amplifier is not designed to receive lower loads provided by hooking the speakers up in this fashion, you might end up destroying your amplifier. Check your manual or consult an expert.
  

Series Resistance

Speakers are hooked up in series to decrease total load to an amplifier. To hook up speakers in series, connect the positive terminal of the amplifier to positive of one speaker, then hook up negative of that speaker to positive of next speaker, and so on. Then hook up negative of last speaker to negative of the amp. It is a lot easier to calculate total resistance for speakers hooked up in series. This is easily done by adding up all the individual resistances:

The disadvantage of hooking up speakers in series other than getting less power out of an amplifier, is that if one of the speakers burns up, the other one(s) stop working.

 Sub Enclosures

This is also a very important part of any system.   With the wrong size enclosure, your sub won't perform as it was meant to, robbing you of heart pounding bass!  See our Building the Perfect Sub Box Guide for more on this subject.

Mounting the Amp

Plan it out first.

• Decide where you are going to mount the amp(s).

• Decide how much, and what gauge power cable you will need.
• Decide how long your RCA cables will need to be. You should take into account that the cable will be running from the center of the car, out to the side, and around several bends and curves.
• When deciding how much power cable, think about how you will run the cables first! You don’t want to get 18 feet of cable, and then realize you can’t go down the middle of the car, you have to go down the side, and it needed to be 2 feet longer!
• It is often easier to just take out the kick panels, and sill plates before starting. It just makes it easier to work, and often you need to do all that anyway. Removing the front seats is optional, but it gives you more room, easier to lift the carpet, and it is often best to run the wires there. As you remove the seats, take note of where they run close to the floorpan. It's easy to accidentally crush your wiring when bolting the seat down, and that is very frustrating. Once you set your mind to it, it’s really not that hard. A cordless drill and a socket set make it a breeze. I have taken apart many an interior in 10 minutes, and can assemble it again in about 15, if I am in a hurry.

Mount the amp(s).

• Find a good solid, flat surface to mount the amp to. Make sure it’s not in a place that will be hot, or not have proper ventilation. Amps can get hot anyway, and you must help them stay cool, for longer life, and less chance of thermal shutdown. If you want, you can mount a board with vinyl, or carpet on it, for cosmetics, and mount the amp to it. You can also mount your power distribution blocks to this board. Mounting to an amp board also reduces the amps contact with metal, and that helps to prevent "ground loops".

RCA's

• Get a good quality set of RCA cables. Normally, a simple pair of shielded RCA's work fine.

• Connect a remote turn on lead wire to your "power antenna" or "remote" lead from the head unit. Run the RCA cables, and remote lead, from the head unit, down the middle of the car, or down the opposite side of the car from the power cable. The remote lead will serve as a turn-on for your amp(s). This doesn’t have to be very thick wire, 16 gauge is fine. If you have room, you can usually remove the sill plate, and lift the edge of the carpet, and run the cable(s) there, proceeding to the back of the car. Be sure not to put them anywhere they will get crushed by anything. Run all the wires to where the amp will be installed.

Positive Power cable

• Find a spot to go through the firewall. Look for a plug that’s already there. If you find one, you can often make a grommet out of it. If there is none, don’t worry. Just find a place to drill, on the same side as the battery, and install a grommet. Run the cable through the firewall, and up to the battery. Don’t connect it to the battery till you are all done. Most cars will have grommets large enough to use. Don't worry if there already is factory wires in your grommet; just be careful not to damage them as you run the wire through. One helpful method is to get a long thick probe (an old car antenna mast works great for this). Grind the tip to a point, but don't sharpen it.  You can tape your power wire to this probe, and run it through the grommet. If your wire is fairly large compared to the grommet, than you may wish to tape a smaller gauge wire to act as a leader.
• Within 6"-18" of the battery, install an inline fuse. For most systems, a 50 or 60 amp fuse is plenty. If it’s only a small amp 30 or 40 will do. DO NOT skip this fuse! This one is mandatory! It could stop your car from catching on fire in an accident.
• With the wire through the firewall, run the cable to the back of the car, staying on the opposite side of the RCA cables. If you are going to have more than one amp, you want to install a distribution block. Connect the power cable to this fuse block. You then run another cable from the fuse block, to the amps positive (+) terminal.
• Be sure to use split loom tubing to protect your power wire under the hood. This is an IASCA requirement. Also, use loom anywhere a wire runs over a rough metal edge. Use wire ties to keep the wire from being drooped over your engine.

Ground Cable

• This is where most people make mistakes.
• Find a spot as close as possible to the amp, to connect a ground cable. You can connect it to an existing bolt, or use a self-tapping screw, or drill, and use a bolt, and nut. If your gonna drill, make sure you don’t drill into your gas tank! The main thing is, wherever you do it, make sure you sand off all the paint, and put it right on the bare metal. You can use some Vaseline here to prevent corrosion, and rust.
• Now connect the cable from the chassis, to the distribution block.
• Run a piece of cable from the distribution block, to the amps negative (-) terminal.

Finishing up

• Connect your remote lead to the amps remote connection.
• Connect your speaker wires to the amp.
• Go back and connect the positive cable to the positive terminal on the battery.
• If you have built-in crossovers, set them the way you will be using them (hi-pass, low-pass, none, etc.….). If they are adjustable, put them approximately where you think will be a good starting point.

Turn the key on

• Turn on your head unit. Put in a good quality CD, or cassette.
• Slowly turn your head unit up to about 80-85% volume. If you hear any distortion, cut it back.
• Go back to the amp(s). SLOWLY raise the gain, and LISTEN for distortion. If you reach a point where the volume is louder then you will listen to, before you hear distortion, then stop there. Otherwise, keep going till you hear distortion, and cut it back slightly till it disappears. Remember that volume setting! That is the max. volume you want to play it at.
• It’s not a good idea to play the head unit at full volume. That’s where most distortion comes in. It may take you a long time to fine tune your amp(s) gains, and crossovers.
• Grab some good CDs (or tapes, if you don’t have CD) and go for a ride. Listen to all types of music, and stop the car, and make adjustments as necessary.
• If you have multiple amps, and an equalizer, it will take much longer to get it set the way you want it. But this is the fun part!