Noise and your New Receiver

Noise in your receiver is often due to a poor ground wire connection.

You've installed a new receiver in your car, and now you've got a noise problem. What can you do? It boils down to this — you made a change that has introduced noise into your system. So, the first thing to do is check out all facets of your installation.

1. Is your receiver securely grounded?
   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.
2. Check to see if you're getting noise on all sources — CD (or cassette), AM, and FM
   If the noise is present only on the radio, then it's coming through your antenna lead.

If you've checked out all potential causes for the noise problem, you may be able to cure (or at least minimize) the noise with a filter. There are three types of noise that can enter your system, and you can find filters that help with each type.

Backway Noise

This is noise introduced through the power and ground wires connected to your receiver. If you're hearing alternator whine (a whirring noise that varies with engine RPMs), you can install an alternator noise filter on the power line between the battery and the alternator to minimize the problem. You can also install a noise filter (American International's S15A (15-amp, 250-watt) or S25A (25-amp, 350-watt) filters, for example) on the receiver's power lead to cut down on signal pollution.

An alternator noise suppressor connects inline between the alternator and battery, and can reduce high-pitched whining noise that modulates according to engine RPMs.

Frontway Noise

This is noise coming from a source within the receiver — either the radio or cassette section (noise from a CD transport is very rare). If you determine that the noise originates with your radio antenna, an antenna filter (like American International's AS100) plugs in between the antenna and your receiver to stop (or minimize) noise from entering your system. Insert a blank cassette and turn up the receiver. If you hear noise, try rerouting the wiring coming from the rear of your receiver to prevent radiated noise from reaching the tape head.

An antenna filter, installed between the vehicle's antenna and the receiver, can minimize noise entering your system from a poorly grounded antenna.

Sideway Noise

This is noise induced by the new receiver's proximity to a noise producer (like a heater motor or car computer). If the noise-causing accessory has a motor, a source noise filter can be installed on the accessory's power lead to minimize radiated noise. If the car computer (or other motor-less accessory) is causing the problem, move your receiver's wiring away from that accessory to minimize the radiated noise.