How To Install Or Replace A Car Stereo Amplifier (also known as a "power amp")
PLEASE NOTE: Disconnecting the battery may result in the loss of setting information in the receiver, clock and other devices in your car. Be prepared to reset your car's equipment as if the battery were being replaced. Do this after the system is installed and double checked. Consult with manual or dealer for intructions. If you are inexperienced or uncertain about any of these procedures, obtain the services of a professional installer.
1) Select a location for the amplifier that has good air circulation, such as in the trunk,or under a seat.
2) Use larger diameter RCA cables to connect the low-level output of the radio to the low-level input of the amplifier.
3) If the radio does not have a low-level output, you will need to use the high level, or speaker output. Generally, this is less desirable because of the noticeable increase in distortion and noise in such an arrangement. If your amp is for bass only, this may be a less significant problem.
4) Connect the power antenna lead from the back of the radio to the amplifier remote turn-on (REM) input. When the radio is switched on, 12 volts should appear on the lead, and start the amplifier when it is connected to the main power leads.
Make certain that the power antenna lead stays on while the receiver is on. On some radios, power may be switched off from the lead when a CD or tape is played, so the power antenna will come down. If this is the case with your radio, it may have a separate lead coming out for the amp turn-on function. Test the lead with a VOM, or test light. When the radio is on, in any function, 12 volts should be present at the amp turn on lead until the radio power is turned off.
5) Check the owner's manual for the recommended gauge (size) of the power and ground cables.
6) Connect the negative, or ground power cables before the RCA cables to prevent damage. If RCA cables are connected first, the amp may try to ground from these cables, possibly causing damage to other components in the system when it is activated.
Use a fuse on the line at the battery and amplifier. Check your owner's manual for the proper rating for the fuse. Fuse your amplifier(s) as close to the battery as possible. Current ratings (in amperes) usually doubles with each amplifier added to a single wire distribution circuit. For example, if you have one amplifier, using a 35 amp fuse, with two similar amplifiers, use a 70 amp fuse.
Ensure that power cables do not run next to RCA signal cables. If the cables are too close, engine noise, which may sound like a high-pitched whine, can get into the system. If whine is unavoidable, you may wish to use a Noise Filter. In addition to having your RCA cables mounted away from power cables, make them as short as possible, as signal strength is lost over distance, and higher frequencies are attenuated.
Connect the main power (+) for the amplifier directly to the battery. Check here for the proper wire gauge.
7) Use the same gauge cable for the amplifier ground (-) as you do for the amplifier battery (+). The ground cable should be kept as short as possible. Find a good ground. Clean the area of rust and paint you select for ground, and bolt the wire to that location. Many of today's cars have fiberglass bodies. Fiberglass does not make a good ground conductor. Ground your amp to a solid piece of metal in either the body or frame. If you have noise infiltration, see our section on Getting rid of Noise.
8) Use 16-12 gauge speaker wire accoding to low or high power, and connect the wire from the speakers to the amplifier. Make sure that the wire connected to the positive terminal of the speaker is connected to the positive terminal on the amplifier and the wire connected to the negative terminal of the speaker is connected to the negative on the amplifier. If using multiple speakers im a mono circuit, avoid overloading from improper impedance matching. See our Impedance Calculator. When making terminal connections, strip only as much insulation from the wire as needed to make a good connection. Twist the wire to prevent any single strand from escaping to touch another conductor.
9) An important indicator of inadequate Power for your system is dimming lights whenever heavy bass is output. Two possible solutions are a heavier alternator, and/or the installation of a large power storage/stiffening capacitor. This last item will store large amounts of power until called for by the amplifier. It is generally less expensive than a replacement alternator, but will not substitute for one if it is needed. See our Capacitors Page.