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Car audio noise suppression guide

Diagnosing and treating noise problems in your car audio system

Noise Suppression Guide

This guide will help you diagnose and treat problems with extraneous noise in your car audio system.

Dealing with static, whining, and buzzing

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. This is especially true if you have an amplifier. The type of noise you're hearing can help determine the cause.

Read over this article for some hints and explanations of what can cause noise in your system. Use it as a checklist, eliminating possibilities until you find the culprit. You can also use this diagnostic flowchart as a guide to walk you through the troubleshooting process.

And don’t forget – if you purchased your gear from Crutchfield, don't hesitate to call on our tech support team (have your Crutchfield invoice handy).

Noise and your new receiver

If you’ve just installed a new receiver, here are two quick and easy starting points:

Receiver with antenna lead, power, and ground

Noise in your receiver is often due to a poor ground wire connection or a poorly grounded antenna.

 

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 (like American International's AS100). This filter plugs in-line between your receiver and your antenna, breaking the ground path between them, thus preventing noise from entering your system.

Antenna filter

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

 

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). This is often referred to as “sideway noise.”

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.

Try using magnetic shielding foil (also called Mu-metal) to shield the back of the receiver or wrap the wire or component that's radiating the noise into your system.

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.

If this is the case, 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 on the receiver's power lead to cut down on signal pollution (American International's S15A (15-amp, 250-watt) or S25A (25-amp, 350-watt) filters, for example). Most often, however, alternator noise comes from a loose or intermittent ground connection. See the section below about noise in the electrical system.

Alternator noise filter

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

 

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.

Amplifier connections
 

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.

Pass more signal from the receiver to the amp by leaving the receiver's volume higher before you set the amp's gain. Experiment until you eliminate the hiss or reduce it as much as possible. A tiny bit of hiss is okay — you won't hear it while driving.

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.

RCA noise

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. Try re-routing them. Separate them from your power cable by at least 18 inches. You could try a better brand of patch cables. The inexpensive RCA cables many people use to connect their components don't have the insulation or conductivity necessary to deflect noise in a metallic, highly conductive automobile.

How much noise your cable receives depends largely on the size of its “loop area” — the larger the loop area, the more vulnerable your cable is to induced interference. A cable's loop area is equal to the distance between its center conductor and outer shield times the length of one complete twist in a twisted pair configuration, or the entire length of the cable in a coaxial type. Consider trading your old cable for one with a twisted pair design. You'll get a smaller loop area and less noise.

Twisted pair patch cables

Patch cables with a "twisted pair" design help reject noise

 

As a last resort, a ground loop isolator (like PAC's SNI-1) can be installed between the receiver's preamp outputs and your amp to minimize this problem.

Noise and whine picked up by the power or ground cables

We discussed ground cables above, because that’s the cause of noise more often than not. If the noise wasn’t due to a poor ground or through the stereo’s antenna cable, it may be coming in through the amplifier's main power cable. Noise can be created by cable of insufficient gauge, so you might try thicker cable.

Ground loop isolator

If you cannot find the faulty ground in your multi-amp system, a ground loop isolator can help minimize the problem.

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 PAC's SNI-1) 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.

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.

If your car is older and hasn't been tuned up recently, you may have ignition noise. It's a ticking noise that varies in speed as you accelerate. You may need a tune-up involving resistor-type spark plugs, shielded carbon-core spark plug wires, distributor cap, and coil.

If the noise doesn't disappear, then your ignition system may not be grounded well enough and is broadcasting ticks to other items such as your air cleaner, hood, exhaust system, etc. Chances are, grounding one of the under-hood components will eliminate the noise. With your sound system on and the car running, try grounding each of these different components of the car. It's possible that grounding one of your car's components will eliminate the noise. If so, make the ground permanent with a braided ground strap.

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. Read our article about The Big Three for more information.

Noise and your nervous system

Noise problems can be very frustrating, especially when you can't wait to hear your new equipment. It helps to remember that you've just placed a very sophisticated piece of electronic gear (a new receiver or amplifier) in the middle of an extremely complex system — your vehicle's electrical wiring. Noise is just nature's way of telling you that something's out of whack. Just run down the list, eliminating possible noise sources until you find the problem.

Crutchfield Tech Support

If you bought your gear from Crutchfield, you could call Tech Support for free help troubleshooting your system. The toll-free number is on your invoice.

  • Peter Goranites from Portland maine

    Posted on 10/6/2021

    help.. help..!!! 1994 Porsche 968 original radio with cassette player. Noise in radio that gets worse when you start driving. Also, no sound from one side, distorted on the other. I am not a car guy. Live in Portland Maine. In July, 2021 I paid a audio store $130 for a bench check, and then another $550 because he said problem is with radio that could only be repaired by sending it away. Got the radio back, same problem, brought it back, now he has had the radio since September and he keeps saying the repair shop that he will not identify is waiting for a part. After reading this article I am terrified that I am getting ripped off. Does your company have a repair instillation facility near me, or can you recommend one..perhaps for a whole new system.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 10/12/2021

    Peter, It sounds like your 27-year old factory radio died, and you found out the hard way that repairing a factory radio is expensive as well as often impossible. Give us a call, so an Advisor can help you pick the perfect upgrade gear for your car.
  • Ten K from Lakeland

    Posted on 10/4/2021

    Thank you guys for the knowledge.. it's very rare for free, keep up the amazing work and contribution to keeping this lifestyle alive!

  • Leonard puga from Hanford

    Posted on 9/7/2021

    Hello! I got 2013 Altima with factory radio and 2 jl audio w3 12s with a mempis amp i got a strong static pop whine noise that cuts on or off when i turn steering wheel it will stop for a bit then come back. It turns off if i disconnect the speaker from amp. I checked all connections and ground to amp thet all connected good. I looked over head unit and the ground is with antenna wire could this be the cause?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 9/7/2021

    Leonard, Ground connections should be made to the car's chassis or directly to the battery, never to another component.
  • Cody from Harrodsburg

    Posted on 8/27/2021

    About to pull my hair out. 07 Escalade. Kenwood double din. JBL amp. Bad whine with RPM, semi bad even with engine off!! Changed / added ground. Changed power wire. Changed to triple shielded RCA. Added RCA ground loop isolator. Added ground from amp to head unit. Added ground from battery to frame. The weirdness - noise is persistent with music paused, but completely gone if I hit mute. (Without isolator, with it the noise just muffles on mute but doesn't disappear) Factory Bose amp had no problems, We assumed it's the new amp. But unhook rca from head unit, directly from amp into headphone jack on phone, clear sound. Help please! ! TIA.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 8/30/2021

    Cody, The fact that the noise went away when you unplugged the amp's inputs shows that the amp and speaker wiring is not the source of the noise. The receiver is the prime suspect, with an internal or external ground connection causing noise that tracks with the engine's RPM.
  • Javier from Caguas

    Posted on 8/15/2021

    None of this recommendations and problems are whats happening to me. I turn on the car, the sound comes out clean, but if I use the power windows, lock the safety belt, put on drive and change from 3-4 gear it present an electrical popping sound, is super annoying. Change the amp, wasn't the problem. Re-install the oem radio and it improve. I'm almost sure is the new head unit :/

    Commenter image

    Buck Pomerantz from Crutchfield

    on 8/16/2021

    Javier, The only thing all those systems have in common, and can affect each other, is a ground connection. Somewhere, there's a bad ground allowing noise to spread to the audio system. Maybe a car repair shop could help find and repair it.
  • Craig from San Francisco

    Posted on 8/12/2021

    My 2006 Acura TSX is making a high pitched whining sound when the radio is off. The radio is stock and my left rear speaker has not been working for a while, but that is where the annoying noise is coming from. Also, the right rear speaker is no longer working either. What could the source of the noise be? Bad speaker?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 8/16/2021

    Craig, Your vehicle's factory stereo features an amplifier that might not be turning off with the receiver, or has other issues. Plus, it sounds like the 15-year old factory speakers may also have issues. Give us a call, so an Advisor can help you pick out the best aftermarket replacement gear for your system.
  • Jason Bilow from Antelope

    Posted on 8/10/2021

    Got one havent seen, I have a pioneer double din with 2 sony amps for maybe 6 years now. Recently when using blue tooth to call people they complain about noise and it gets worse as I speed up or down, I dont hear this noise or any noise in the speakers etc. Only the callers hear it, to the point they cant even talk to me, been getting worse. Blue tooth going out?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 8/12/2021

    Jason, You're describing a failure in the Bluetooth microphone or its circuitry. Maybe you have a loose connection.
  • Maans Kotze from Mosselbaai

    Posted on 8/5/2021

    Totally something else. I built a new car radio into my glass-fibre caravan. I have 220v and 12v deep cycle battery in my caravan. The battery is charged by an electric charger when necessary. The radio is connected on 12v of the battery. The radio has a noise especially when the battery is charged. I noticed when I was at my house the problem was solved but once I camp the noise was very bad. The antenna is an ordinary car wire antenna and is within the caravan in a canal. On my recent tour, I found 2 fellow campers who basically have the same problem. Any advice would be appreciated.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 8/5/2021

    Maans, RVs and campers, caravans in your country, are notorious for quirky electronics and other problems. The only advice I can help you with is to check and adjust all ground connections. The fiberglass body will probably require you to run one or more ground wires directly to the battery, instead of a chassis ground.
  • David from Earlysville

    Posted on 7/13/2021

    I had Crutchfield install a Pioneer AMFM radio in a Toyota Tacoma about two years ago. I noticed it is making a consistent clicking noise in FM mode only and only when vehicle engine is running. The clicking noise goes up and down with the volume. Any thoughts on what to check first? Thanks

    Commenter image

    Buck Pomerantz from Crutchfield

    on 7/14/2021

    David, The first thing you should do is call us, and make an appointment for our installers to check out your system and fix anything that's not working correctly, if possible.
  • Dale J Morrison from Shoreline

    Posted on 7/7/2021

    Hi there. I have a 2004 Ford explorer sport trek. I had a Kenwood touch screen receiver put in several months ago. Sometimes it doesn't happen for a while. But for a length of time intermittently, when I turn the vehicle off and open the door and the receiver shuts down, there is a high pitch whine. The vehicle is off. When I start the vehicle, the receiver turns on and the whine stops. The receiver works great and no noise until I turn the vehicle off again which lasts until I start it again.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 7/8/2021

    Dale, It sounds like your receiver or vehicle may have some electrical issues. Take it back to your installer and see if they can fix them.