Car Audio Wiring

Car Audio Power Wire

Power wire is one of the most important parts of an amplifier installation. The proper gauge is the second most important consideration, next to fusing. The proper gauge should be used so that the amplifier is not choked off by the size limitations of the wire. If you use too small of a power wire you can get a large voltage drop between the battery and the amplifier. This voltage drop can cause distortion in the output and even cause the amplifier to shut off if it is equipped with under-voltage protection. When selecting a power wire, be sure to purchase one that has many hundreds or thousands of strands so that it will be easier to install and will not break when passing around sharp corners. Also make sure that the jacket of the wire is of a material that will resist chemicals such as oil and battery acid that it will encounter in the engine compartment.
When running power wire always make sure to cover it in protective wire loom in the engine compartment and to use rubber or plastic grommets when passing through any metal or abrasive surface. Otherwise the power wire can chaff and eventually short out.

Car Audio Speaker Wire
Speaker wire is also important in terms of size and strands for the same reasons but the jacket is not as important because it will not see the same chemicals as the power wire. When shopping for speaker wire, look for oxygen free copper (OFC) wiring. The size of your speaker wiring depends on the amount of power going to your speakers and the length of wire from the amplifier to the speakers. Most systems will need to use 16 gauge to 12 gauge wire.

Car Audio Signal Cables
Signal or RCA cables are also important for their noise rejection properties. Cables range in price from a couple of dollars to over one hundred dollars a pair. Most decently priced cables in the twenty to thirty dollar range (for a twenty foot pair) should be adequate for most listeners and noise situations. Twisted pair cables offer much better noise rejection properties as opposed to coaxial cables (the most common). Twisted pair cables consist of two small gauge wires that are twisted around each other in a helix pattern. Coaxial cables are one small gauge wire jacketed by a braided cable which are then both encased in a plastic jacket. The advantage of the twisted pair cables is in the twist in the cables. By twisting the cables noise picked up by one cable will theoretically be canceled by that same noise in the opposite cable. Twisted pair cables can be difficult to find so ask for them specifically when buying RCA cables.

Features and terms that may be encountered with regard to wiring are:
Butt Terminals: This type of terminal resembles a long barrel and is used to connect small gauge wires together. These type are crimp terminals and considered less desirable than soldering when soldering is an option. These terminals are also sometimes referred to as crimp connectors though that term can apply to many variations of crimp terminal.

Deep Cycle: A battery usually reserved for marine use that can be drained and replenished many times. While popular years ago many installers have relegated this battery to system use only with a traditional car battery for main power.

Farad (F): The base unit of measure for capacitor storage. One farad is very larger and is equivalent to one million microfarads (uF).

Gauge: This refers to the diameter of the wire. The smaller the number, the larger the wire. Sixteen is common for speaker wire, eight is common for average size amplifiers, while four gauge and below is used for large amplifiers. For reference, four gauge wire is about the same diameter as the average male pinky finger.

Gel Cell: A type of battery that uses a gel type acid. These batteries can be desirable because they may be mounted upside down without the danger a standard type battery would pose.

Heat Shrink Tubing: A type of insulating plastic that resembles a drinking straw. A small portion of this tube is cut off and placed on a wire before soldering. After the connection is soldered and cooled, the tube is slid over the joint and shrunk around the wires by means of a heat gun or hot hair dryer.

Microfarads (uF): The more common unit used to measure capacitor storage. One million microfarads is equivalent to one Farad.

OFC: An abbreviation for oxygen free copper. This is the most desirable wire to buy and there is really no reason to buy any other kind. As the name implies it is pure copper that is free from oxygen impurities.

Spade Terminals: A type of terminal used on most speakers. The type found on speakers are male spades while the ones used to connect to these terminals are female spades. These terminals are also referred to as quick disconnects though this name can apply to many different types of terminals that come apart quickly.

Voltage Rating: Referring to the amount of voltage a capacitor is rated to handle. The very least a capacitor used for reinforcement should be rated at is 16 volts while 20 volts is much more desirable and available on the slightly more expensive capacitors.

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Car Audio Show Competition Organizations

Car audio shows are one of the most exciting things in the car audio hobby. They bring together people of all backgrounds that share a common love for car audio and competition. There are four major car audio show competition organizations. If you think competing is right for you, check them out below. Not all car audio show organizations are available in all areas.

IASCA - The oldest car audio competition organization and also the largest. IASCA has traditionally been associated with sound quality competitions but has more recently added the idBL, an SPL (boom car) category. Their sound quality segment, SQ, has seven categories and only two power classes, 1-600 watts and 601+ watts.

USACi - Once the new kid on the block, USACi has become a major player in the sound off scene. USACi also has two competition formats, SQ (sound quality, basic and advanced categories) and SPL (boom car). USAC was started with the idea of bringing fun back into car audio competitions. There are two power classes in each SQ division (0-600, 600+) and several in the SPL competitions.

dB Drag Racing - Started and led by veteran competitor and soundoff legend Wayne Harris, dB Drag Racing is just what the name implies. Competitors boomin side by side for the title of loudest vehicle. The measurements are displayed on a large drag racing type "tree" and are very exciting to watch. dB Drag is all about SPL. If you want to be a boomer than you need to look into dB Drag Racing. Competitors are classified by the number of woofers in their system and the extent to which their vehicle has been modified.

MECA - MECA classes its SQ competitors by the extent of vehicle modification. Competitors are classed as either Amateur, Street, Modified, Modex or Extreme. MECA also offers SPL classes in similar categories.

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Choosing a Quality Amplifier

Also keep in mind the quality of the amplifier. A generally good indication of quality build and the power output is the size and the weight of the amplifier itself. Better quality amplifiers will usually have a heavier and larger heatsink versus a low quality amplifier of the same power rating. Do not accept size as a definite indication though. I bought an amplifier at a yard sale for two dollars that was two feet long, eight inches wide and two inches tall that had a five inch square circuit board inside of it. This amplifier was so poorly built that I could actually hear the music I was playing coming from the circuit board itself. However there are many top quality amplifiers that do not follow this rule. The ever growing Class D (and its variants) amplifier is much more efficient and there does not produce as much heat or use as much power. This means a smaller power supply and a smaller heatsink. Because of the high efficiency design of those amplifiers a heavy heatsink is not required.

Also a good indication of an amplifier's true output is the size of the fuse used. True two hundred watt amplifiers do not use a ten amp fuse. Use your head when buying and keep in mind the brand's reputation for quality. A quick and dirty way to check the true power output of an amplifier is to take the fuse value of the amplifier (or the sum for multiple fuses) and multiply it by 6 for class A/B amps or 10 for class D amps (higher efficiency). This is by no means an accurate way to judge power but it will tell you if your amp is even close to it's specifications. For example, if a class A/B "1,200 watt" amplifier has a fuse value of 25 amps then you can take 25*6 and get 150. So this "1,200 watt" amplifier is more in the range of 150 watts.

If you find yourself on a budget or lack space for many components then the economical thing to do is buy a multi-channel amplifier with the built in features and processors that you desire. This can save a lot of room and several hundred dollars in added component and installation cost. The quality will be a little less as compared to outboard processors but will probably not be noticed. Also, by minimizing the number of components the chance of noise entering into the system is lessened.

Some features and aspects of amplifiers to consider are:

Bridgeable: This feature allows a pair of amplifier power channels to be combined into one channel of greater power. This is usually used for driving a subwoofer although it will work with any other type of speaker as well.

Channels: A channel is one power (speaker) output of an amplifier. The more channels an amplifier has the greater the installation flexibility it will have. Especially in terms of options, future add-ons and upgrades.

Class: This refers to the way the amplifier operates. The three types that are most likely to be encountered are A, A/B, and D. Class A amplifiers are the least efficient in terms of power consumption, staying on continually, but also have better sound in general than A/B amplifiers. They are very, very rare in car audio. Some argue non-existent but in any case don't expect to see any. Class A/B amplifiers are more efficient than the class A design and are the most common type. Almost all amplifiers in the car audio market are of the A/B design. Class D amplifiers are usually reserved for high power subwoofer amplifiers and can reach efficiencies in the 80%+ range. This design can therefore be smaller, uses less current and produces less heat than the other classes. However there are some full range Class D amplifiers becoming available.

Connectors: This is the method of attachment used for wires that are connected to the amplifier, including speaker and power wires. The most common kind is the screw terminal strip. This is a series of screw connectors that can be removed and replaced without compromising the amplifier. The other main type of attachment is the "Molex" type connector. This method involves a wire harness that plugs into the amplifier after the power and speaker connections have been made with a crimp or solder connection. If the amplifier is installed in more than one system these wires can get pretty short over time and become more difficult and even dangerous to work with. A variation on the two is a harness that the power and speaker wires screw into. Then the harness plugs into the amplifier. This is probably the most convenient of all connections. Virtually all amplifiers use the screw terminal strip though many older amplifiers used the Molex or straight wire connections.

Crossover/Filter: A built in crossover can be useful, especially if it is many frequencies of adjustment. A filter is a crossover that only affects one channel, not actually splitting frequencies but simply reducing a range of them. Most amplifiers that have built in filters will have the option for either Low Pass (LP) or High Pass (HP). If you see AP on the filter that means "all pass" which basically means the filter is turned off and passes all frequencies.

Distortion: This is often given as T.H.D. or total harmonic distortion. It is the measure of how much an amplifier will change a signal from the input signal it is given. Figures below 0.1% are negligible and will probably not be heard. Usually the figure can be in the 3% range without being heard but virtually all high quality amplifiers will have a T.H.D. below 0.1%.

Efficiency: This is the ratio of of power input (from the battery) to power output (to the speakers). A 100 watt amplifier with an efficiency of 50% would take in 200 watts of power from the battery and output 100 watts of power to the speakers. The other 100 watts of power would be wasted as heat. The higher the efficiency of an amplifier the better. Most class A/B amplifiers are around 50-60% efficient and Class D around 80%. Amplifiers are generally less efficient at low power and more efficient at full power so this number varies in actual use.

Power Output: The rated power output of an amplifier should be given into a four ohm load, all channels driven from twenty to twenty thousand hertz (20Hz-20kHz). Keep in mind that while the low end amplifiers are exaggerated in their power output, many high end amplifiers are under-rated in their power output. These are sometimes called "cheater amps" because they allow a car audio competitor to compete in a lower power class while in reality having a larger amplifier. This under-rating may be three times less than the actual power output. Look for the CEA 2006 standard when comparing amplifier power.

Power Supply: The two most common types are the IC chip and the MOSFET supply. The IC chip is what is used in most source units (head units) and are only capable of producing about eighteen watts per channel. MOSFET is the more common design and has a smoother sound than the chip design.

Pre-amp Inputs: This is a set of jacks (usuallyRCA Jacks) that will accept a low level pre-amp signal from a source or processing unit.

Pre-amp Outputs: This is a set of jacks (usually RCA Jacks) that pass on a low level pre-amp signal to another amplifier or processing unit. These will sometimes be filtered outputs.

Separate Gain Controls: This allows the gain of each channel of the amplifier to be set independently of the other(s). This allows you to more evenly match the amplifiers channels.

Speaker Level Inputs: For source units that do not have pre-amp level RCA outputs this feature may be used to take the signal from the speaker leads of the source unit. The signal will not be as clean as a pre-amp level output but will be adequate for most factory upgrade applications.

Stability: The measure of how low of an impedance load an amplifier can handle (in ohms). Any good quality amplifier will be two ohm stable while a rare few will go as low as a quarter of an ohm. Ideally an amplifier should double its power each time the load is halved. For example, a one hundred watt amplifier (into a four ohm load) should produce two hundred watts into a two ohm load and so on. This is most useful when running multiple speakers off of a single amplifier or in sound off competitions that are classed by total power output.

Tri-Mode Output: This feature is available under different names but is the ability of an amplifier to run a stereo pair of speakers and a mono subwoofer (or center channel) from only two channels of the amplifier. Personally, I would not recommend doing this. Instead buy a good quality four channel amplifier and bridge two of the channels for the subwoofer.

Tube Amplifiers: These are the least common amplifiers and are also the most expensive. Rather than the traditional solid state components they use old fashioned vacuum tubes. They are said to produce a warmer sound and a smoother midrange than solid state designs. For most systems the standard design will be more desirable.

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Basic Electrical Upgrades

A vehicle's electrical consists of many parts but the ones we're interested in are the battery, the alternator, and the power wiring. A vehicle electrical system is a 12 volt DC system. The primary source of power when the vehicle is NOT running is the battery. The primary source of power when the vehicle IS running is the alternator. This is a very important point so remember it. The primary functions of the battery are to start the vehicle and provide power when the vehicle is not running. Because the battery's stored power is so great it is important to treat it with respect. It's the automotive equivalent of a loaded gun. It has the power to stop your heart and can burn your vehicle up if an unfused power wire is shorted to ground. Always remember to disconnect the negative battery cable before doing any work on a stereo system. NOTE: If your radio has a security feature that requires a secret code to be input after power has been disconnected make sure you know this code before you begin.

Depending on your car's factory electrical system, you may not have enough power to run your aftermarket stereo system. You probably do unless you have a multi-megawatt system or an extremely tiny alternator. If your battery goes dead often after the installation of your new stereo you may have an electrical system problem. Have your battery and electrical system tested by a qualified technician. If everything checks out then you probably are in need of an upgrade. Here are some of the common problems and their likely cures.

Adding a Second Battery
Many people are under the impression that adding a second battery will cure their electrical problems. If one battery is good then two must be better. Right? Wrong. Remember that the function of a battery is to start the vehicle and to provide power when the vehicle is not running. The only thing a second battery will help you with is "parking lot" listening time. Basically it will provide you the additional capacity to run your stereo longer without starting the vehicle. After the vehicle is started the second battery becomes another load on an already overworked alternator. If you do replace your battery I would recommend getting one from Optima or one of the other specialty battery manufacturers such as Stinger or Rockford Fosgate.

Upgrading Your Alternator
Frequent dead batteries are a good indication that your electrical system isn't keeping up and you may need to upgrade your alternator. Doing so will give you more juice to run all of your electrical components, including your stereo system, without looking to the battery for help. The problem is your alternator is undersized for your new electrical requirements and has to look to the battery to provide the extra power, resulting in shortened battery life. Have a qualified technician verify this before investing in a larger alternator. Hopefully you can find a larger alternator from your vehicle's manufacturer that will interface with your existing system. Consult the manufacturer or the local dealer to find out about this. If not then you can look to the aftermarket manufacturers to see what is available. Check with Ohio Generator or Stinger for high output models.

Power Capacitors
Another solution is to add a power or Stiffening™ capacitor. This device acts as an electrical storage "buffer". It stores power until needed for high electrical demands such as heavy bass notes. If your headlights dim when you have you stereo cranked then you MAY benefit from one of these. This is most noticeable when music with a heavy beat is played. Your headlights will dim to the beat. This is being caused by a voltage drop that is being created by the large power demands of your amplifier(s). A power capacitor will help fill in the gaps in the energy required by your amplifiers. Because of their low internal resistance they can deliver a lot of power much more quickly than a battery can and can often prevent this voltage drop.

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