How to suppress unwanted noise from your car radio.

This guide will help you to detect and also deal with problems with extraneous noise in your car sound system. Dealing with buzzing or other unwanted noise resonating through your car Radio can be a serious headache in any car journey. Maybe you’ve just set up a brand-new receiver or amplifier in your car, you were excited to listen to your new sound system but instead, you were disappointed to be greeted by a hair-pulling noise problem. Here are the three most likely irritating sounds that people with a new or old radio system experience:
  • Radio static
  • Amplifier Hum
  • Buzzing audio speakers
The first step in rectifying the problem with your car radio is to identify the source of the noise is. Noise can be introduced right into your system from a number of sources. There is no need to freak out, this post is here to help! Here I will break down the most common causes of unwelcomed noise and how to Suppress it. You can utilize this diagnostic flowchart as a guide to walk you through the troubleshooting treatment.

Did you just have a new receiver installed?

If you’ve only recently had a brand-new receiver installed, below are two easy steps you can take to resolve the problem at hand:

1.) Make sure your receiver is grounded correctly.

An inaccurate ground is one of the most major causes for presenting noise into your car’s sound system. For example, the ground cable may be located near another source of noise (like a home heating a/c, computer system, or system)?

2.) Check to see if you’re obtaining noise on all sources

If the noise exists just on the radio, it’s likely coming from your antenna lead. Firstly, disconnect the antenna. If the noise disappears, then you should install an antenna noise suppressor (Click Here to find one). This suppressor works by connecting in-line in between your receiver and also your antenna, breaking the ground in between them, hence preventing noise from entering your system.

Here is an example of an external Car Antenna

Inkwina, CC BY-SA 3.0, via Wikimedia Commons

Radiated noise

Still not working? Try pulling the receiver from the dash while a CD is playing and see if the noise persists. If the noise disappears, it’s being radiated into your system because of the receiver’s proximity to a noise source (like a heating system, electric motor, or car computer system). If the noise-causing tool has a motor, a noise filter or suppressor can be fixated upon the gadget’s power in order to reduce emitted noise. If the car’s electrical system (or another motor-less accessory) is triggering the issue, you can move your receiver’s electrical wiring away from that device to minimize the radiated noise. Attempt using magnetic shielding aluminum foil (furthermore called Mu-metal) to shield the rear of the receiver or cover the wires that are the causation of your car radios noise.

Engine static and alternator whine

Noise generated through the power as well as ground cables attached to your receiver is called engine noise or alternator whine. You might hear a whining or clicking noise if the engine is your offender. Its pitch will commonly vary with engine speed.

You can install an alternator noise filter on the power line in between the battery and the alternator to lessen this issue. You can likewise install a noise filter on the receiver’s power to decrease signal contamination (American International’s S15A (15-amp, 250-watt) or S25A (25-amp, 350-watt) filters, as an example). The majority of generator noise originates from a loose or periodic ground link.


Here is an example of what your Alternator looks like.


Have you recently installed a new amplifier?

An amplifier can pump sound right into your system via bad ground or inadequate installing. Rubber grommets or feet can help separate the amplifier from the framework of the car, a possible resource of the noise.

Where is the amp installed?

Is it near something that could be radiating noise, like a rear-mounted tuner or computer system? If so, unbolt it and move it away and see if the noise stops.

Next, inspect your ground cable

Ask yourself is the ground cable properly connected to the vehicle’s chassis with a clean connection? Your ground cord ought to ideally be 18″ if it is a lot longer it can set off noise issues.

Examine the framework

If you have an external amplifier in your system, the very first thing to do is to dull out any kind of system noise, which sounds like a regular, or consistent hiss. Look out for any system noise while the engine off.

Check the RCA Cable

Noise can be a result of a faulty RCA spot cable linking your components. To examine this, detach the cable from your amp. Put one side (left or right) of a spare cord and connect it into the amp. Switch on the radio system as well as the engine. If the noise is gone, reconnect the cable to the amp, and detach them from your receiver. Your spot cable is the cause if you hear the noise again. Take into consideration trading your old cable for one with a twisted collection design. You’ll get a smaller-sized loop place and also less noise.

Here is an example of what RCA cables look like.

Noise in speaker circuitry

Noise can also come in through the audio speaker wires. If the noise is still there, then it’s being radiated right into the audio speaker wires.

Noise from the electrical system

If you have attempted every one of the noise-suppresing suggestions and you’re still getting a buzzing, whine, or hiss, then the concern may be with your truck. You might just need to load your battery with fluid. Have a mechanic check your generator and battery.

If your car is older and hasn’t been tuned up recently, you might have ignition noise. It’s a ticking noise that differs in rate as you increase.

If the noise does not vanish, after that your ignition system might not be grounded great and is passing on ticks to various other things such as your air cleaner, hood, exhaust system, and more. With your stereo on and also the car running, attempt grounding. It’s feasible that grounding amongst your car’s components will remove the noise. Make the ground irreversible with a braided ground.

Can bad spark plugs cause radio noise?

Bad spark plugs can cause noise which is also known as, ‘Engine Rattle’ and this sound can radiate through the stereo system as it can be picked up by the antenna system.

The best way to stop or prevent engine rattle is to replace your current spark plug wiring with the resistor type. If that fails, consider installing a capacitor at the coil.

Why does touching a radio antenna reduce static?

You may have noticed that your radio interference stops when you make physical contact with your antenna. The reason for this is that the human body picks up radio signals (especially am signals) the same as your cars antenna. When you touch the antenna or go near to it, the signals picked up by your body are added to the antenna and thus increases the quality of your signal.

If you have noticed that when you touch your radios receiver the static or other unwanted noises goes away this means the issue is related to your radios signal. Replacing or repairing your car’s antenna should fix your issue.

Will aluminum foil boost radio antenna signal and reduce noise interference?

Aluminum foil acts as a conductor and therefore efficiently picks up radio signals. Technically attaching aluminum foil will boost your radio signal and prevent signal interference. Although this does work with a standard home radio this is not a good idea for a moving vehicle. The foil will most likely loosen or even blow away in the wind.

There are plenty of better ways to improve your signal such as installing a booster or getting a new head unit.

Why does my radio interference stop during the night?

Some radio stations’ signals might be improved during the night; the reason for this is because of a change in the ionosphere.

The ionosphere is known to reflect certain radio signals and at night its composition changes allowing for higher reflecting signals   thus better quality signals.

Can my aerial amplifier be the cause of unwanted radio interference?

Aerial amplifiers are not usually a cause of radio static unless they are installed incorrectly. If you have recently installed a new stereo system or have had other electrical work done to your car then this is more likely the cause. You should check that all the connections are correct and secure by following the guide above.

Should I Buy an Alternator Noise Suppressor or does my alternator need to be replaced?

If you have determined that your alternator is creating unwanted noises from your car radio you might be wondering whether or not your alternator needs to be replaced or repaired or if a simple alternator noise suppressor is all you need. 

Technically a noise suppressor will be effective for removing the interference to your radio but if your alternator is making a loud humming sound then it may be at its end of its life and need to be replaced soon. You can read more about the importance of Your Alternator for Powering your vehicle here.

If you can only hear the alternator wine from your car then an alternator noise suppressor will be fine.

How much does a car sound suppressor typically cost?

The price of a radio interference suppressor can vary based on the quality and the type that you require. If you are in need of an alternator suppressor expect to pay about 15 dollars including shipping. For an ignition suppressor standard pricing would be 20 dollars with shipment. You can also find car plug condensers for about 15 dollars as well.

Do Car Radio Boosters Really work?

If you have issues with static or other interference you might be considering purchasing a radio booster to solve this issue. A Car Signal booster doesn’t actually boost the AM signal; what it does do is increase the gain after your antenna has received the signal. What this means is that if your radio is randomly cutting out and losing signal altogether then an antenna boost won’t do anything at all. In this case you should read our article about what to do when your car radio has no signal. If you have got some radio audio that is faded then a booster will be the perfect solution.

How do you test a car radio antenna?

In order to test a radio antenna you will need to have a multimeter. An ohmmeter is a very cheap and useful tool that will enable you to check the resistance in any electrical circuit. 

Once you have an ohmmeter you will need to do three tests in order to determine whether or not your static is being caused by the receiver. Before conducting these tests you should consult with your owners manual for your own safety. Once you have familiarized yourself with all of the safety procedures outlined by your manufacturers you should disconnect your antenna from your car radio.

` Test 1.) Connect one lead from your OHM meter to the top of your antenna and the other wire to the antenna port on your radio. Take a look at the reading of your OHM meter, you are looking for a low resistance i.e Less than five.

Test 2.) This time atach one of your meter cables  to your antenna wire and the other to the bottom of the satellite itself. Again you will be looking for a reading with a small resistance.


Test 3) In the final test you are going to make sure that there is no connection linked between your radio port and ground. To do this, connect one lead of your OHM Meter to your radios pin and one the second to the antennas cable, this time you should see an Infinty symbol(Typically a number 8). If you see an infinity symbol it means there is no connection to ground.

If you are still suffering with static interference and are totally convinced that it couldn’t be anything else but your antenna then you should consider whether it could be a tuning issue.

If an antenna is too long it can result in a poor quality of sound and similarly if it is too short it can have the same effect. Many modern antennas have a tuning tip which will allow you to adjust the length of your receiver.

Park your car in a spacious area, ie an area where there are no objects that could be causing more radio static. Then use a screwdriver to turn the antenna’s tuning key. Adjust the antenna length by a ¼ INch each time and test the radio until you find the best results.

If you have a dual antenna system you will need to make sure that both antennas are the exact same length.

My radio is creating a buzzing sound. What should I do?

A low buzzing sound from your radio is usually the sign of a poor connection to ground. Check all of your radio and speakers connections as mentioned in the guide above.

Weird Car Radio Noises only before the car warms up?

If you hear buzzing or static noises only when you first start up your car it might be a slightly loose wiring connection which is the cause. When your car warms up so do the wires in your electrical system and the cables connect. If it is cold then your car cools down and contracts the wires which loosens the connections.

Why is there buzzing coming from my car when my radio turned off?

If you are hearing a faint buzzing sound even when your radio is completely turned off it is likely to be caused by a wire that is not properly grounded this is especially true in the event that you recently upgraded or modified your sound system.

Why does my radio cut out in the rain?

You may have experienced your car radio seemingly randomly cutting out in wet or icy conditions. This is due to the OTA being bounced off the surface.

Is car radio static always a technical fault?

An unwanted buzzing, static or hissing noise coming from your car stereo doesn’t always mean that there is a technical repair required on your car. If you live in a remote area or an area with a lot of hills or trees the poor quality of sound might just be a result of a lack of coverage. Before you decide to bring your car to a repair shop you should test your car radio in an area that is known to have a lot of signal.

We have done our best in this article to answer any questions in relation to an unwanted noise that is coming from your car radio. If we missed something, or you have any further questions, why not leave us a comment and we will get back to you. If you are in need of more car repairs or modifications you should check out the rest of our content!