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Jeep Car Stereo System - What's Audio All About?

Posted in How To on November 1, 2005
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OK, what's an audio installation doing in the pages of 4 Wheel Drive & Sport Utility magazine? Here's the deal, I looked back though the archives of 4WD as far as I could and I couldn't find a single audio story. Now, this type of tech might not be very important to our hard-core readership and you might think I'm nuts, but hear me out. We all like music, and in most cases music only enhances an experience. We also know that music makes a long road trip driving to and from the trail enjoyable. Also, for every person that owns a trail-only rig, there's an enthusiast who uses his daily driver as his adventure vehicle.

Since I'm treading new ground with this article, I'm not going to kill you with a full-on technical installation crammed with the specifications of a full-on audio and visual system. There's also no way I'm going to show you where each wire of a stereo system gets connected. I am going to answer your questions and give you the basics and a starting point for a quality high-fidelity (old term, I like using it) system.

As long as I have been able to enjoy quality technology, Boston Acoustics has stood out as a leader in the audio industry. My expert high-tech audio friends confirmed this after conferring with them. Since 1979, Boston Acoustics has been producing high-end equipment for home and automotive listening pleasure. I decided if I was going to write this article, I was going to show you some very reputable products.

After initial contact, Boston Acoustics shipped a bevy of components that would fit into Project Grand Caddy (Jeep Grand Cherokee) with minimal customization. I was told the system also offered awesome sound, and could endure the dusty rigors of off-road. The vehicle already had a Clarion head unit and Sirius Radio.

We received: one four-channel amplifier for the front and rear door speakers, model GT40; one two-channel amplifier for the subwoofers, model GT22; four door speakers, model SX65; two 10-inch subwoofers, model G210; and one Neo Type S Imaging System (tweeters).

Next, we contacted Joe Komaromi, the proprietor of Pacific Audio & Alarm, for installation. Joe has been in business for more than 20 years. We were referred to his shop by other magazine editors; they had nothing but praise for his knowledge and understanding, and the highly skilled craftsmanship of his staff. Joe is also an electrical engineer and up on engine tech; he completes some really amazing engines swaps and performance upgrades.

Once the professional installation of the system was complete, I was floored with the high-quality sound of the components. Even though I'm not a sound-system expert, I was truly impressed with the overall installation and end result. The ensemble offered everything we were hoping for and more. We highly recommend Boston Acoustics for mobile and home audio, and Pacific Audio & Alarm for technical assistance, installation, and equipment.

Q & A On Stereo System Basics
Q: What is the most important thing to look for while shopping for a quality stereo system?
A: The most important thing to look for when shopping for a stereo system is to find one that meets your individual needs. Remember, aftermarket anything implies custom, so tailor the system to work for you. For example, don't sacrifice the durability of your rig to include your audio, but rather build your system to withstand the same rigors the rest of your vehicle does. If you want a system that is weatherable like the rest of your "open top" rig, then choose components that will work. They are available.

Q: What's the best way to test a system before purchase?
A: The best way to test a system before you buy is to take your CD collection down to a stereo shop that has a sound wall that will allow you to try any combination of speakers, subs, amplifiers, or head units. Ask the salesman to act as your CD changer. Tell him to shut up and allow you to audition until you have questions.

Q: What do quality amps do besides boost power?
A: Amplifiers boost power, but even more so, offer more control over the speaker at lower and higher volumes. You're more likely to blow a speaker by giving it too little power (at higher volume levels) than by giving it too much power. Many of today's amplifiers also clean up the power to the speakers.

Q: What are the most common misconceptions people have about stereo systems?
A: The most common misconceptions people have about systems is that an amp is an amp, a speaker is a speaker, and a CD player is a CD player - not true. Find a CD player that works well for you ergonomically - speakers that sound good to you, and equipment that meets your budget.

Q: Explain watts. Is more really better?
A: Watts? The truth about watts is that many manufacturers print misleading numbers on their packages. While this practice used to be grossly mistreated, today it is better. In mobile audio there are many variables that can/will affect the actual "power" of your amplifier, be it head unit or amplifier. First, the amount of power (voltage) your component receives will affect the amplification of that power. Many manufacturers list power output measured with 14.4 volts input. However, most alternators, particularly those taxed by lighting and other common off-road gadgets, are outputting 12 volts or less. The impedance, or load, on the amplifier also determines its effective output. For example, 2-ohm speakers will be more difficult to drive (however, less stable) and therefore the amplifier is effectively delivering more power. Look for components rated with an RMS or "Continuous" power rating. Typical ratings only list "peak" power delivery, which is often far greater than the actual power delivery. The amount of "line level" voltage from the head unit to the amplifier (RCA connection) will also aid the amplifier as the signal is stronger, thus the amplification effects on that signal are greater. Some head units today offer 4-volt output.

Q: Explain ohms. What are they really all about?
A: Ohm is a formula that determines the amount of relative resistance a speaker or component has on the electrical system it is connected to. For example, a 4-ohm speaker has more resistance than a 2-ohm speaker. That said, do not be misled to believe that less resistance is better. An amplifier requires some amount of resistance to be stable. A 2-ohm speaker may play louder, but the amplifier will lose the Damping Factor, which is its ability to control the speaker. Thus, less resistance can cause distortion. Try to design a system with 4- to 6-ohm loads on the amplifier.

Q: What speaker materials (cones) are good and bad? What are the differences?
A: "Nice cones. Paper or plastic?" There are many, many, many types of speaker cone materials. They can be simply broken down into two basic categories: paper and polypropylene. The idea between the variance in materials is to create a cone material that is as light and as rigid as possible. Each material type has trade-offs. Paper and impregnated-pulp cone materials have outstanding "audiophile" traits and transient response, but are not suitable for open-air installations for obvious reasons - they can't get wet. Polypropylene cones are durable and an excellent choice for most tastes.

Q: What does magnet size have to do with sound?
A: Magnet size has everything and nothing to do with the speaker's performance. What I mean to say is that the magnet is actually a motorstructure. And like any motor, size can play some role, but the power of the engine - or in this case, the power of the magnet - can greatly determine a speaker's performance. Not all magnets are created equal. The motorstructure holds the magnet, voice coil, spider, and pole piece, but should also work to cool the speaker while in operation.

Q: Is bigger wire better? What does factory and smaller-gauge wire do to sound quality?
A: Whether bigger wire is "better" is arguable, dependent on the application. The most important place to use heavy-gauge wire (four-gauge or better) is to the power the amplifier. Larger-gauge wire is generally needed when the runs (length is longer) or the demand is greater, such as the amplifier's draw on the battery. Sixteen- to 18-gauge (AUG) is fine for most audio speakers, though you may run heavy-gauge to subwoofers if the power or length or the run warrants it. Too small of wire (at any point) can greatly impede the performance of a speaker or amplifier. So while there's no harm in going bigger, there can be harm in going smaller.

Q: What should a person use for connections? Is soldering better?
A: Soldering is typically thought to be the best connection because it is time-consuming. Actually, however, crimping the wires using "butt connectors" is the most durable, particularly for off-road use where the connection points may become wet. Solder will rust and eventually fail. For the most durable connection, I crimp and wrap with heat shrink or electrical tape.

Sources

Boston Acoustics
Peabody, MA 01960
978-538-5000
http://www.bostonacoustics.com

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