A common problem in many car audio installations, especially your first installation, is a problem with the amplifier. These problems can vary from crackling, popping to just plain not working. Here's the step by step process to determining where the problem might lie.

 

Determining the Cause of the Problem

First you need to tear the amplifier down to it's most basic state. Remove all of the speaker wiring and RCA's and leave only the power, ground and remote leads connected. This is basically the minimum connections for the amplifier. If you still have a problem in this state then either your amp is defective or you may have an installation problem such as the amp touching metal. Check to see that the your mounting screws haven't gone through your non-conductive amplifier mounting surface. You did mount your amplifier to a non-conductive surface didn't you?

Also check to make sure your amplifier has power, ground and a remote turn on signal. It's time to break out the voltmeter and test these connections. Your amplifier should have a power on LED that will let you know when it is on. It will usually be green or blue, but can be other colors. Check your owner's manual to know for sure. Some LEDs will turn orange or red (protect mode) when there is a problem with the amplifier or its installation.

If it's OK in this state and you have the correct power connections then start reconnecting the other wires until you find what causes the problem. Add the RCA cables first. If this doesn't cause any issues such as the protect light coming on then add the speaker wires one at a time. If the speaker wires cause the problem then they are probably touching the metal of the vehicle.

If the speaker wires are touching the vehicle it will often cause a motorboat effect from your speakers. Check to see that your speaker wires or the speaker's terminals aren't touching in places such as the rear deck. This is usually where the problem occurs. It's also possible for the speaker wires to become pinched by a seat or other vehicle part which can cause the wire to become grounded.

If after performing these steps you still can't get your amplifier working then it may need a trip to the repair shop (Tweeter, Best Buy, Circuit City). If it's under warranty then make sure you follow the proper procedure set by the manufacturer. Call the manufacturer if you're not sure.

Alternator Whine in Car Audio

The biggest offender of noise in the car audio environment is alternator whine. Alternator whine is caused by a difference in electrical potential (voltage) between two points. It's usually caused by a ground connection that is less than ideal. The main culprits are the amp, the head unit and any intermediate components such as crossovers and equalizers. Basically any component that touches the low level music signal (from RCA cables). It's usually cured by finding the source of the noise entrance and re-grounding that component.

Troubleshooting Car Audio Noise

You can usually isolate the head unit as the problem by disconnecting the RCA cables from the amplifier and inserting a muting plug (RCA plug with the connectors shorted together). This also eliminates any noise from components upstream of the amplifier such as crossovers and equalizers. If the noise is gone then you need to check the other components upstream of the amp. First, connect the head unit directly to the amplifier (assuming you have crossovers or equalizers between the two). If the noise is gone then your problem is the intermediate components. If the noise returns then it is a head unit problem.

In almost every case you will simply need to find a better ground location for that component. Clean, bare chassis metal is the best solution. Many times installers will use whatever factory bolt is handy and that can work and it can cause problems. Factory bolts are not a bad source necessarily, but if they have other electrical components using them as a ground this can be a source of noise. If you're not using a new ground point then you'll want to make sure your factory bolt meets the criteria above.

The next step isn't as much fun but it's needed to know for sure. Remove the deck from its mounting location and place it on top of the amplifier. Put a non-conductive barrier between the two (T-shirt is fine). Hook up the deck's power leads to the amplifier's power terminals. Then connect the deck to the amp with very short RCA cables. Male to male RCA gender changers are about the right length. If there is still noise then it's a very rare deck problem. Most likely it's coming in on the cables. A switch to unshielded, twisted pair RCA cables should usually cure that.