One of the most daunting tasks of installing a car audio system is running all of the wiring to and from the amp — and doing it correctly and securely. Snaking power wires from the battery, around the engine compartment, through the firewall that separates the engine compartment from the interior, and then though the interior — behind trim panels and under carpets — until they all end up at the amplifier is a task that calls for skill, resourcefulness, and a cool head. It also requires taking parts of your car apart and putting them all back together again. Check out Figure 13-1 for an example of a wire’s route through a car.
On top of this routing obstacle course, you have to make sure that all of the wiring is routed in a way that ensures it won’t get damaged or pinched.
If you’re installing multiple amplifiers, wiring accessories such as power- distribution blocks, grounding blocks, and fuse blocks will help organize and distribute the various wires and fuses that are needed. These are often mounted as close as possible to the amplifiers they service.
Before you take on wiring up an amplifier for the first time, you should know what you’re getting into. Seek advice from a professional installer or experienced DlYer, or turn to one of the forums and users groups available online.
When you speak with an experienced installer, be sure to ask the following questions:
- Where and how will you mount the amplifier so that it doesn’t interfere with my use of the car (for example, carrying groceries, luggage, and so on)?
- Can you install the amplifier in such a way that I can take it out when I sell the car or when my lease is up?
- What’s the manufacturer’s warranty if the amp is professionally installed versus if I do it myself?
- If I bring my car in for service and the mechanic has a question about the amplifier installation, how can I get in touch with you?
If I haven’t scared you off and you decide to install your own amplifier, check out online forums or users groups for advice. I suggest starting with http://forum.elitecaraudio.com, www.audiogroupforum.com/csforum, and http://caraudioforum.com.
Making a Fuss other Fuses
An amplifier gets its power from a car’s battery, which is part of your car’s electrical system. If you decide to install the amp yourself, it’s of paramount importance that you understand the principles of proper fusing. A fuse is a component of an electrical system that protects the circuit, or more specifically the components — the equipment and wiring — within the circuit. Short for fusible link, a fuse usually contains a small metal wire or strip that melts when a higher current than it can handle flows through it, thereby opening the circuit so that the excess current can’t flow through. All amplifiers require an external fuse to protect them from an electrical short. Such fuses are sometimes supplied with the amplifier and may plug directly into it.
Getting in-line
But even more important than an external fuse is the in-line fuse on the power wire that runs from the car’s battery to the amplifier. (In-line means that the fuse is in line with the wire; that is, the wire is cut and the fuse is inserted into the space between the two cut ends of the wire.) Although the in-line fuse also protects the amplifier from a short in case something happens to the wire, more importantly, it safeguards the automobile and its electrical system. Think of the in-line fuse as a fire break: In the case of an accident, when a short circuit creates an electrical fire, the fuse opens the circuit to prevent current from continuing to flow.
or see Began for Installing Speakers
You can buy an in-line fuse from your local car audio shop, an electronics store, or online. Most all-in-one amplifier wiring kits also come with an in-line fuse. A circuit breaker can also be used in place of a fuse, although this option isn’t very common.
Most professional installers place the amplifier power cord’s in-line fuse as close to the car’s battery as possible. That way, if there’s a short, the fire doesn’t travel far. Just imagine how far the fire would travel before it’s automatically put out if, say, you decided to mount the in-line fuse in the trunk!
Respecting the fuse ratings
Paying attention to the rating of the fuse is as critical as placing it in the right location. One of the cardinal rules of car audio is that you must always use the proper fuse for a given wire size. That means never substituting a fuse or replacing a blown fuse with one of a higher rating. Inversely, never replace a wire supplied or recommended by a car audio equipment manufacturer with a smaller gauge wire. Otherwise, you risk damaging your components and your car. The rating of an in-line fuse should be as large or slightly larger than the one for the amplifier. For example, if you have a 30-amp fuse protecting the amp, you would want a 30- or 40-amp fuse on the amp’s power wire.
The owner’s manual for an amp usually specifies the fuse rating required for the amplifier and its wiring. And if you are using multiple amps, add up the fuse ratings for each to come up with the size you need on the power wire.
Although substituting fuses may be tempting when you’re ready to rock and roll and don’t have the correct fuse handy, remember that its purpose is to protect your equipment. The amplifier manufacturer specified the fuse for a reason. Ignore it, and you may find out why. Just consider what it will cost you to replace a fried amp as opposed to a 50-cent fuse.
Separation of power
One of the most common sources of unwanted noise in a car audio system comes from RCA cables carrying tow-level audio signals coming into close proximity to parts of the vehicle that radiate Electromagnetic Interference (EMI). Some of the biggest culprits are components that require a lot of juice: motors for power seats, power windows, and convertible tops. The list goes on and on. Factory power cables can also introduce noise into a system.
Thai's why it's important to route signal cables as far as possible from potential noisemakers. Of course, car audio power wires also radiate EMI, so it has become standard operating procedure for installers to route signal cable on one side of a vehicle and power wiring along the other, so that they are as far apart from one another as possible.
Staging Grounded
Besides a power wire, your amplifier also needs a ground wire, which is usually black. The ground wire needs to be the same size as the power cable and has to be attached to a solid metal part of the car. It also should be as short as possible so that it doesn’t add electrical resistance; as resistance increases, the ground becomes less effective and the amplifier works less efficiently. A short ground wire also reduces the chance that the wire will pick up electrical interference and therefore introduce noise into the system. See the sidebar, “Separation of power” for more information on the introduction of unwanted noise.
If you mount your amplifier under the front seat, for example, you can attach the ground to one of the seat’s anchoring bolts. In the trunk, the ground can be attached to part of one of the shock towers or another metal structure.
see more Protecting Your System and Yourself : Securing and Insuring Your System
But if there’s no easy grounding point nearby, you can create your own by drilling a small hole into a metal part of the car — just make sure you know what’s on the other side before you start drilling — and then inserting a sheet metal screw along with a star washer that the ground wire can in turn be attached to. You may need to scrape paint or some other factory coating off to get down to bare metal for a good ground, and if you live in a rust-prone area, you’ll want to treat the area with rust-proofing or undercoating when you’re done.
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