Car Audio Noise Trouble Shooting

You've installed a new receiver or amplifier in your car, and now you have a noise problem. Noise in your audio system commonly comes in these three forms:

• Radio static
• Amplifier whine
• Buzzing speakers

What can you do? The trick is to determine what the source of the noise is. Noise can be introduced into your system from a number of sources.

1. Noise and your new receiver

- Is your receiver securely grounded?

Improper ground is one of the biggest causes for introducing noise into your audio system. Is the ground wire located near a noise source (like a heater, air conditioner, or computer)? Is the ground wire actually connected to the vehicle's ground? Since the antenna lead can act as a ground (thereby enabling a new receiver to operate without its ground wire properly connected), the antenna lead is frequently the source of noise problems.

- Radio static can be caused by antenna noise

Check to see if you're getting noise on all sources — CD, auxiliary/USB, AM, and FM. If the noise is present only on the radio, then it's most likely coming through your antenna lead. Unplug the antenna. If the noise goes away, try an antenna noise suppressor.

- Radiated noise

If the noise isn’t coming in through the antenna, try pulling the receiver from the dash while a CD is playing. If the noise goes away, it's being radiated into your system due to the receiver's proximity to a noise producer (like a heater motor or car computer).

- Engine noise and alternator whine

Noise introduced through the power and ground wires connected to your receiver is called engine noise or alternator whine. If engine noise is your culprit, you may hear a whining or clicking sound. Its pitch will usually vary with engine speed.

2. Noise and your new amplifier

An amplifier can introduce noise into your system through a bad ground or through a poor mounting. Rubber grommets or feet can help isolate the amplifier from the chassis of the vehicle, a potential source of noise. If all else fails, install a noise suppressor. The tricky part is figuring out which step or steps to take. Please read the rest of this section and try some of the simple tests.

- Where is the amp mounted?

Is it near something that could be radiating noise, like a rear-mounted tuner or computer? If so, unbolt it and move it away to see if the noise stops. Remove your patch cables. If you still hear noise, check to see if your amp is isolated from the vehicle's chassis. Any contact between your amp's metal casing and your vehicle's body could cause noise problems.

- Check your ground wire

Is it securely attached to the vehicle's chassis with a good contact to clean metal? Your ground wire should ideally be 18" long at most — a longer ground wire can cause noise problems. Improper grounding causes most system noise problems.

- Check your gain structure

If you have an external amplifier in your system, the first thing to do is to quiet any system noise, which sounds like a constant, low hiss. First, check for system noise with the engine off. Insert a CD and put your CD player on pause. Listen to the system with the volume way down, then way up. Put on music. If you hear hiss or static in either instance, reduce the gain on your amplifier.

- Noise in the patch cables

Noise can be picked up by the RCA patch cables connecting your components. To test this, detach the cables from your amp. Insert one side (left or right) of a spare patch cable into the amp's left and right input jacks (see illustration below). Turn on your system and engine.

If the noise is gone, reconnect the cables to the amp, and disconnect them from your receiver. If you hear the noise, your patch cables are definitely picking it up.

- Noise and whine picked up by the power or ground cables

Multiple amplifiers can also create ground loop problems, which can usually be solved by grounding each amplifier with its own separate wire. If you are unable to locate the cause, a ground loop isolator (like Recoil Audio GLIRCA, GLI35, NF35，MGLI) can be installed between the receiver's preamp outputs and the amplifiers to minimize this problem.

- Noise in speaker wiring

Noise can also come in through the speaker wires. To test them, turn the system off and disconnect the speaker wires from the amps. Now start the car. If the noise is still there, then it's being radiated into the speaker wires. Reposition them, or, as a last resort, shield them by wrapping them with Mu-metal foil.

3. Noise from the electrical system

If you've tried all of the noise-fighting tips above and you're still getting static, whine, or hiss, then the problem might be with your vehicle. You might simply need to fill your battery with fluid. If that doesn't help, have a mechanic check your alternator and battery.

A very effective fix for electrical system noise is called "The Big Three" upgrade. This is where your vehicle's battery charging wire and chassis ground wires are augmented by adding large gauge wires (1/0- or 4-ga.) to those connecting the alternator to the battery's positive pole, the battery's negative pole to the chassis, and the chassis to the engine block. This establishes better current flow and more consistent voltage, which improves your system's signal to noise ratio. It also ensures against loose or restrictive ground connections, which, as said before, are common sources of noise. Check Recoil Audio PGB3 wiring kits for more information.