In This Chapter
► Providing your system with extra power
► Keeping your car quiet
► Installing accessories
► Essential tools for DIY installers
Car audio enthusiasts just can’t leave well enough alone, and you should be thankful for that. Hardcore car audio types aren’t satisfied with a great-sounding system: They always think it can sound even better. This relentless pursuit of perfection has brought us accessories that help squeeze the nth degree of performance out of a system.
Many of these innovations grew directly out of enthusiasts involved in sound- off competitions seeking just a little bit of an edge. Now, once-novel accessories such as capacitors and sound-deadening material have become a standard part of any high-performance car audio system.
In this chapter, I look at some of the accessories that can give you more power, eliminate unwanted noise, and make installation easier.
More Pouter to You: Capacitors, Batteries, and Alternators
Your car’s charging system isn’t designed to power a high-end car audio system. Car manufacturers design a vehicle’s charging system to handle the load that all of a car’s electrical components — including headlights, wind¬shield wipers, and air conditioning — place on it. Then they factor in a margin of error for those times when you may be using most of the car’s major electrical devices at once, like at night, in a rain storm, during the heat of summer.
Carmakers also realize that people may add aftermarket accessories to their vehicles, such as car audio systems. At some point, the car’s charging system runs out of juice if you keep placing demands on it by adding more electrical components. Fortunately, you can do a few things to get more power.
Music is transient in nature, meaning that there are loud and soft parts, so the demand a car audio system places on a car’s charging system isn’t constant, as it is with, say, a car’s headlights. Your charging system may handle just fine music that isn’t very dynamic (for example, music that doesn’t have lots of loud and soft parts, such as mellow music with just an acoustic guitar and voice).
But with music that is very dynamic with lots of loud and soft parts (think of a rock, rap, or pop song), your electrical system is asked to provide power in quick bursts during the loud parts. When a deep bass note hits in a rap recording, for example, the amount of power provided by the charging system may sag a bit, and the amplifier powering the subwoofers in turn can’t deliver the full audio signal without distorting it. Distortion in large quantities can even cause a speaker to blow or fail.
That’s why innovative car audio enthusiasts have come up with ways to solve these power problems. Accessories such as capacitors, auxiliary batteries, and high-output alternators are added to a car’s charging system to provide extra juice when the music in a car audio system demands it.
Capacitors
Capacitors are used in most electronic products, and it’s common to see many of them populating a circuit board. These cylindrical devices store power the way a reservoir stores water. So when a circuit needs a bit of juice, the cap releases it. A capacitor is able to deliver power more rapidly than the car’s charging system because the power capacitor has a lower internal resistance, which allows it to quickly discharge.
In the early 1990s, car audio sound-off competitors started adding large capacitors to their sound systems to provide instantaneous power when peaks in a musical passage demanded it. Before long, car audio-specific capacitors became available to the masses, and now they are a common sight in most high-end systems (see Figure 19-1).
Capacitors are easy to install for even a beginner DIYer. See the section, “Installation Tips for Accessories,” later in this chapter for more on how to install them.
Capacitors are rated in Farads, which is a measure of how much power they can store. The rule of thumb is to use 1 Farad of capacitance for every 1,000 watts of power. So if you have a 500-watt system, you would need a 0.5-Farad capacitor.
Capacitors are available in Farad ratings ranging from 0.5 up to 40 for extremely high-powered systems, and vary in price from $75 for a 0.5-Farad cap to more than $500 for a large-Farad version. Besides Farad rating and shape, capacitors also differ in features, with some sporting built-in digital voltage meters and power-distribution blocks. You can buy a capacitor from most car audio retailers, and they’re available online from e-retailers such as Crutchfield (www.crutchfield.com).
You probably don’t need a capacitor if you have a modest system without a subwoofer, but you could probably use one if your system includes at least one subwoofer. If you have several amplifiers and multiple subwoofers, adding a cap or two can definitely improve your system’s performance.
Whether you need a capacitor also depends on how much current your amplifiers draw from the vehicle’s charging system as well as the type of music you listen to. If you primarily listen to bass-heavy rap music and your headlights dim every time your system hits a bass note because of the strain on your car’s charging system, a capacitor could help. (You should also have your car’s electrical system checked to make sure it’s up to snuff, however.) Or if you think the total current draw of all of the amplifiers in your system starts to exceed the capacity of your car’s alternator, you’ll probably want to add a cap.
Auxiliary batteries
Adding an extra battery to your system doesn’t provide more power, but it does let you play your system with the engine off. Listening to a system, especially if it’s a high-powered one, with the engine off is a sure way to end up with a dead battery. Some enthusiasts, mainly sound-off competitors, add a battery solely dedicated to providing power for engine-off listening. Because of the complexity of adding a second battery, this application is best left to the most hardcore car audio enthusiasts and installation is best left to professionals.
If you do decide to add a second or auxiliary battery, it’s a good idea to use the same type of battery as your main one. You should also install a battery isolator, which is a device that electrically isolates the auxiliary battery from the starting battery. This way, if the auxiliary battery’s power is depleted, it doesn’t affect the starting battery. Although a battery isolator isn’t required, it can prevent you from getting stuck with a dead starting battery.
Two types of isolators are available. A diode isolator is the most straightforward and trouble-free, but can create a slight voltage loss. This means that both batteries won’t charge fully, although this is rarely a major problem. A solenoid isolator employs relays or switches to regulate the flow of current with practically no loss of voltage, but they are not as reliable as diode-based isolators.
Batteries made specifically for car audio applications are now available, and can be used for a starting battery, an auxiliary battery, or both. These are usually dry cell batteries, meaning they don’t contain liquid like traditional lead-acid car batteries. They are also typically deep-cycle batteries, meaning they can be discharged and recharged repeatedly, and they recharge quickly.
High-output alternators
An alternator supplies power for all of a car’s electrical components, including a car audio system, when the engine is running. At the same time, it also charges the battery, which powers all of a car’s electronics when the engine is not running. As I mentioned previously, your car’s charging system, and the alternator specifically, are designed to provide enough power for all of a car’s electrical components and then some. Your car’s standard alternator should do okay with a moderately powered system that only includes, say, a couple of amplifiers, as long as you’re not constantly cranking it up.
But if you plan on installing a bunch of amplifiers and subwoofers, your alternator may not be able to keep up with the current demands placed on it. That’s why some companies sell high-output alternators for car audio purposes (see Figure 19-2). Be warned: Upgrading your car’s alternator is a major modification that affects the rest of the electrical system and is a complex and costly undertaking. It’s an upgrade needed by only the most hardcore car audio enthusiast and crank it up competitors who are trying to achieve the highest sound pressure levels (SPL) possible. These folks typically upgrade the alternator in show vehicles that aren’t driven on a daily basis — their vehicles are more for show than go. Upgrading the alternator just to get a few more decibels of bass from your system isn’t worth the cost, hassle, and potential adverse effects on your car.
Figure 19-2:
A Stinger Electronics high-output alternator.
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