Installing an amplifier the way the pros do it!

By Grizz Archer

Look inside the driver’s-side storage compartment, peek underneath the bunk, or poke your head around the front wall of a sleeper and what you are going to see on many of today’s custom rigs is the heart of the truck’s sound system.

It’s not the least bit unusual to find a pair of high-end amps, colorful wiring, and maybe even a couple “caps” neatly displayed. Truckers love their stereos and they love keeping up with the times.

Some of the systems have been professionally installed, while other installations are the works of a do-it-yourselfer. Both function perfectly if done right. If the installation isn’t done correctly, well, wasted money follows wasted time.

Installing a sound system, especially amps, appears very elementary to the novice audiophile: Just run some wires, hook them up and call it a day.

Unfortunately, the result of such a plug-and-play mentality leads to a way under-performing audio system or, at worst, a total burn-down of the components and truck.

There is a proper way to do everything – and installing audio amps is no exception to the rule. My recommendation for the audio DIYer is quite simple: Grab a beer, chill out, and formulate your own installation plan following these basic guidelines.

SORTING IT ALL OUT

Audio amps generate a lot of heat, and therefore they need to be mounted in a location where they can stay cool, yet away from moisture and high humidity.

Likewise, an amp’s mounting location should have very good ventilation; amps can get hot anyway, so you must help them stay cool for longer life and less chance of thermal shutdown.

Mount the amp(s) on a solid, flat surface. Amps utilizing metal mounting tabs can bring in “ground noise” if the truck is poorly grounded.  Such amps may benefit from being mounted on a non-metal surface to isolate the amp’s chassis from secondary ground.

Another factor to take seriously is making sure you have the proper gauge power and ground cable, and speaker wires. Running power/ground cable that’s too small for the job is a sure recipe for big problems.

The typical size for audio power cable in a truck varies. This depends on a lot of variables from length of the run between battery and amp to the output and amp draw of the system. You can refer to The12Volt.com for a cable chart to make a wise selection.

Running the signal/remote wires down one side of the vehicle and the power cable down the other side is old school and is not required these days. Run the remote with the primary power cable and install an in-line fuse holder for the power wire no farther than 18 inches from the battery terminal connection. This is a critical safety component.

This fuse protects your truck from burning up in case of the power wiring shorting out. The wire between the fuse and the battery terminal will be unprotected, which is why you want this section to be as short as possible. The fuse size depends on the current the power wire will carry. Consult the owner’s manual of your amplifier(s) to find out the maximum current draw of your system.

You can also contact the manufacturer and ask them for that information. For multiple amplifiers you will need to add up the maximum current draw of each amplifier.

Once you know the maximum current draw you’ll know what size fuse to use. For example, if your maximum current draw is 50 amps then you’ll need a 50-amp fuse. Insert the fuse after all other connections are made.

WELL GROUNDED

Having a good ground is even more critical than the proper size power cable. The battery is actually the best ground since there are no ground loops caused by a battery ground, amplifier ground, processor ground and any other separate grounds. (As a precaution, I always run a pair of remote wires so that if there is ground noise due to a loop, I can connect the extra wire from the radio ground to the amp ground terminal.)

First, make sure the ground cables from the battery bank to the frame, engine and body are in perfect condition and plenty big. (The cables should be the same size or larger than the positive cables.)

Don’t be afraid of overkill here: You spent good money on your amps and the rest of your system. Don’t skimp on a couple feet of new ground cable now.

Find a spot as close as possible to the amp(s) for the new ground point.  The spot must be free of paint , primer, soil and grease. Don’t use a self-tapping screw to mount the ground cable because only 1-2 threads is not enough to safely secure a heavy cable.

Soundstream power distribution block is great for use in custom rigs.

The best place to ground the amps is to the frame or, better yet for custom rigs, through a ground distribution block. If you want the installation to be really sick, install a Soundstream Powerplant or PowerPlant 2 ground/power distribution block, depending on your requirements.

If you cannot find a good place with factory hardware, scrape the paint and drill a hole to accept a good old-fashioned nut and bolt.  Make sure you can get to both sides of the hole so the connection is tight.

Once the ground cable is connected, spray a cable connection sealer over the connection point, or use silicone spray or spread a little Vaseline or other petroleum-based product to keep the bare metal from corroding over time and losing the ground.

As you run the wires, be very careful to make sure none can be pinched or have a wayward screw go through them when interior and/or trim pieces are re-installed!

THE OTHER CONNECTIONS

Once the power and ground cables are taken care of, the next item(s) to address in the amp installation are the RCAs. Again, these are a critical component of a good audio installation.

Oft times, you can run an RCA 15 feet and get horrific noise in the speakers. “Ma Bell” figured out many years ago twisted-pair signal cables yield clear signal free of noise.  By definition in this topic, noise equals voltage difference.  Twisted-pair RCAs eliminate signal induced noise, but there are still other types of noise.

Twisted-pair RCA cables, such as they offered by Soundstream, help maximize an audio system's performance.

So what about shielding?  Shielding normally connects to the ground ring on the RCA end, ruining the whole benefit of twisted pair!

Double- and triple-shielding is just a marketing gimmick that is not only worthless, but it’s actually much more expensive and worse than a standard inexpensive twisted-pair RCA.

Then you have the Remote Turn On. This wire is normally connected to the “AMP” or “POWER ANTENNA” blue wire on the back of the headunit/radio. This wire switches on the amplifier(s).

Note: If you are adding an amp to an OEM radio, it is best to add a 12V switch to turn on the amp.  Do not hook it up to the ignition wire.  Yes, this will work, but it is not a safe practice.

After all the wires and cables are run, go back and use split-loom tubing to protect the  power wire and power cable. Use zip ties to keep all wires and cables clean and tidy, and to keep them from rubbing on anything sharp.

FINISHING UP

Connect the RCA cables to the amp(s). Do not connect them before you have grounded your amplifier, and wait till you connect the battery terminal.

Often, the biggest mistake people make is to have their RCA’s hooked up the first time the amp(s) get a charge. Since the outer shield of the RCA’s are grounded, the amp will try to take some of its ground through them, damaging the preamp of your headunit and amplifier.

Connect the remote lead to the amp’s remote connection. Connect the speaker wires to the amp. Then go back and connect the positive cable to the positive terminal on the battery.

Now, if your amp(s) have gain controls (and most do nowadays) turn them all the way down to the minimum setting and then back up about 10%.

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. If you have no idea, it would beneficial to talk to a truck-audio professional.

Turn the key on. Turn on the headunit. Play your favorite kick-ass song. Slowly turn the volume of the headunit up to about 80-85 percent. If you hear any distortion, cut it back.

Go back to the amp(s) and very slowly raise the gain while listening for distortion. If you reach a point where the volume is louder then you will be listening and there’s no  distortion, stop adjusting.

Otherwise, keep raising the gain until you hear distortion, and cut it back slightly until it disappears.

A note about volume: Never crank it above 85 percent as most radios will begin to clip the signal and cause distortion.

Now, grab some good CDs and take the system for a test drive. Listen to all types of music. If adjustments need to be made, make them as necessary.

If you’re using a preamp, line driver, EQ, and other processors, and you don’t know how to set all of the gains, please read my related article on “Multistage Gain Setting.”

Amplifier Installation Tips

A power amplifier’s performance is only as good as its installation. Proper installation will maximize the system’s overall performance. It is recommended that you have our product installed by an authorized Soundstream retailer.

However, if you decide to install it yourself, please follow these safety tips and take your time to do a quality installation:

• Fuse amplifier’s power wire at the battery.
• Be sure to fuse the power wire within 12″ of the truck’s battery. This will protect the truck’s battery in case of a short circuit between the power amplifier and battery.
• THIS IS A MUST, the amplifier’s built-in fuse will only protect the power amplifier not the truck’s battery.
• Use high-grade wire connectors. Use Proper power wire size for maximum current transfer and safety. Improper size power and ground wire can reduce the amplifiers power and poses a risk of damage to the amplifier and the vehicles electrical system. Please follow the recommended “Amplifiers Power Cable Requirements” to ensure maximum power transfer and safety.
• To ensure maximum power transfer and secure safe connections, it is recommended to use high-grade barrier spades (for connection at amplifier) and terminal rings (for connection at battery).
• Do not run any wires underneath vehicle. Exposed wires have a chance of being cut or damaged. It is best to run all wires through the vehicle under the truckpet and/or side panels. This lends to a cleaner installation and less risk of damage.
• To avoid possibility of induced noise from the truck’s electrical system (i.e. popping noises or engine noise), Keep signal wires (Speaker or RCA) away from any electrical wires.
• In order to reduce the chance of ground loops (i.e. engine noise); make the grounding wire as short as possible to reduce the wire’s resistance. Also, when using multiple components, make sure all units are grounded at the same point.
• Avoid sharp edges when running the wires. When laying wiring inside the truck, watch for welding burs in channels throughout the truck. If necessary adequately grind, finish sand or fill in around any ruff spots so wires will not be punctured by sharp protrusions. Use a grommet to protect wire when running through the firewall or bodywork. — CR