Engine noise and any other noise that comes through your car’s audio system is like nails on a chalkboard. What’s worse is that there could be many factors contributing to this, and you will need to check them all.
To get rid of engine noise in a car stereo, all ground wires must have a correct gauge and secure connection to the chassis and also signal and power cables cannot run together to the amplifier. If wires are connected correctly, and you still can hear the engine noise, you will need to install ground loop isolators or noise filters.
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Let’s take a look at what all the possible causes could be to why your car audio system is experiencing strange engine noise or interference. After that, I will show you all the remedies for these causes so that you can enjoy crystal clear sound without frustration.
What causes engine noise in a car stereo?
In some cases, the engine could be the culprit causing noise in your car’s audio system.
The noise will emanate due to the alternator. You can solve this by installing an alternator noise filter on the power line between the battery and the alternator to minimize this problem.
I will look at noise filters in the subsequent heading later in the article and will explain to you which are suited for which situations.
Noise associated with a ground loop from a mobile device
This cause of noise in a stereo is becoming more and more apparent. This happens when you have a mobile device, and you connect it to your car audio system (radio or infotainment unit) with an RCA or USB connection.
In essence, this type of connection will work fine, and you should not have any problems (the sound should be clear and noise-free). However, when you simultaneously connect the mobile device to the adapter used for charging, the problem comes in.
The sound you hear may be in the form of static (white noise through your speakers), or it may be in the form of a whine (this will happen you tend to rev or accelerate your engine).
The phone being connected to the car via two connection points causes what is known as a ground loop.
Insufficient grounding from the amplifier can cause noise.
Sometimes car audio fans will opt not to use their mobile device. Instead, they will install an aftermarket stereo system that will consist of aftermarket amplifiers, speakers, and perhaps even a new stereo or infotainment system.
And this is a great solution to improve car audio sound quality. However, it is always upsetting to find that there is noise in your system after spending a long time and your hard-earned money on replacing or upgrading your car stereo.
This noise can come in the form of hissing, static, or whine (this changes with the car’s speed or when the engine is revved).
Most commonly, this type of noise is associated with bad ground. To illustrate this better, every amplifier you want to install requires two connections.
- One is the power lead, which will power and run the amplifier.
- The other is a ground connection, and this is the one about which many new car audio enthusiasts forget about when setting up amplifiers.
A ground connection may just be a bolt or some form of a connection point that is not as prominently visible as the other connections. If you do not run a ground wire directly from the battery, the connection point should be close to the amplifier, in most cases in the trunk area.
What needs to be done is that a wire with the same gauge at the power wire should run from the negative amplifier terminal, and then it should be connected (solidly) to the chassis of your car.
What causes a bad ground connection?
Not connecting the ground cable to the amplifier or car correctly.
The ground wire has to be connected to a metal part of the chassis of the car, and it has to be fastened close to the amplifier. Connecting it to any other part of the vehicle which is not metal will not cause the ground wire to function correctly. Hence you get noise emanating from your car stereo system.
In addition to the ground wire not being connected to the car correctly, some people do not correctly connect it to the amplifier. When connecting the ground, you need to make sure that both connection points are firm and are solidly connected.
Having the incorrect wire gauge for the ground wire
Not as commonly known as having a bad connection point, noise can occur because the wire gauge (the wire diameter size) is sometimes too small when compared to that of the power lead that is running to the amplifier.
When the ground wire is thinner than that of the power wire, this can lead to noise and interference.
I know that thinner wire can be cheaper, but the ground connection is as important as the power connection, so make sure that the ground wire is as thick as the power cable running to your amplifier.
Amplifier noise due to the mounting position can cause noise.
In some cases, if the amplifier is mounted too close to another device in your vehicle that emits some electrical signal, then this device could interfere with your amplifier, causing it to make unnecessary noise.
Keep in mind that this could be any electrical device irradiating an electrical signal (a seat motor or anything similar).
Amplifier enclosure causing a short to ground can cause noise.
This is not a typical short to the ground where a fuse will blow, and there will be an excessive overload of power, causing your audio equipment to blow.
This concerns a type of short circuit where there is interference in the circuit. Such interference is dependent on individual amplifiers that are produced by specific manufacturers and that are housed in a metal casing.
Depending on the amplifier, what will sometimes happen is that if the amplifier that is housed in a metal casing is bolted to the chassis of the car (the metal casing is touching the metal chassis of the vehicle) directly, it will then cause noise and interference.
Incorrect gain settings on your amplifier can cause noise.
One thing that car audio enthusiasts don’t take into consideration is the gain setting on an amplifier. This needs to be adjusted and set correctly, and if you have a complete aftermarket audio system, then the entire system should be tuned rather than just an amplifier.
This will negate the chance of you interfering with any settings that can cause your audio system to make any noise or give off any interference whatsoever.
Signal connection cables can cause noise.
Signal cables of a mediocre quality are also a widespread problem and are associated with noise and interference in your car audio system.
Many car audio fans shell out a ton of money for great gear such as top-shelf amplifiers and speakers and skimp on the wire, which is the incorrect choice to make.
These low-quality signal cables will pick up interference and noise along the signal path and run it straight to your speakers.
I saw that many times, and it is like buying a Ferrari and put it on some budget tires. Would you do that?
A noise that is radiated into the speaker wire itself
Speaker wires usually do not cause many problems, but it can still happen, especially in older cars with the aged electric installation.
If you have tested and gone through the list that I have laid out for you and still can’t find the noise or interference source, this could be the problem.
As with signal wires picking up noise and interference, so can speaker wire. Hence, if any electrical component is located near the speaker wire, then it may be susceptible to interference and noise.
Aftermarket head unit noise
The last significant reason you could be experiencing noise is when you replace the standard OEM factory stereo with an aftermarket head unit.
This could happen because the stock ground connection within the dash is not good enough for the aftermarket head unit. Although rare, but if this will happen to you, you may need to replace a car stereo harness or run a separate ground wire to the head unit.
How do I stop my car radio from making noise?
Below I have detailed all the remedies for the above situations that could be causing your car audio system to make a noise.
Keep in mind that you should consider all the fixes before going out and purchasing any components.
Install ground loop isolator (noise filter) for mobile devices
One easy fix in correcting a ground loop caused by your mobile device is purchasing and using a BESIGN ground loop noise isolator.
This little device simply slots into the signal path between your phone and car stereo, essentially negating the ground loop. Furthermore, this fix is relatively cheap and will not set you back the price of a whole new stereo or getting a mechanic to rewire your car stereo. The only requirement is that your car stereo must have a 3,5mm jack input.
Install ground loop isolator (noise filter) for signal paths and amps
This ground loop isolator is similar in its function to that of the isolator for mobile devices, but it has to be placed between the signal cables of your audio system and not the 3.5mm jack cable of your mobile device and stereo.
You should consider purchasing this device only if you have gone through all the steps and measures to determine and rectify what could be the cause of your car’s audio system noise.
I have installed two InstallGear ground loop isolators in my Ford Edge, and the result was immediate. I am driving with them for over a year now, and I am delighted with InstallGear quality.
If you do not have RCA outputs in the head unit, you can use BOSS B65N RCA converter noise filter instead and connect it directly with the speaker wires from your car stereo harness.
Are noise filters any good?
As I mentioned earlier, you can get various noise filters that you can install in different areas of the car audio, but their purpose is mainly the same.
Ground loop isolators are classified as one type, and they are the first option that people tend to drift towards.
The other types of noise filters are explicitly classified as noise filters and then noise suppressors. These work well and are similar in respect to ground loop isolators. However, these noise filters speeding on the type will connect to different sections of your car, trying to eliminate noise.
One type of noise filter that is the most commonly used is the one you can connect between the battery and the alternator.
Ground loop isolators and other various noise filters are surprisingly quite useful for reducing noise in your car audio system. However, you have to consider all the factors that could be contributing to causing the noise in your car’s audio system.
If you don’t consider all possible factors that could be causing your audio to have noise or interference, then installing a noise filter will not solve the problem with the noise, and you may think that they are a waste of time and money.
For example, if your ground wire is not secured correctly or too thin, then the noise filter (ground loop isolator) may not function correctly.
Concerning the grounding wire
As we briefly touched upon, you have to ensure that your amplifier’s ground wire is secured on the amplifier and in the section where it makes contact with the car.
I also mentioned that your ground wire from your amplifier has to be the same gauge (size) as the power wire running to your amplifier.
Lastly, do not forget that your vehicle’s actual battery has a ground wire. It is also imperative that this wire is fastly secured and connected correctly to the proper connection points.
Do take note that the ground connection of the battery completes the circuit. If you install a very powerful aftermarket amplifier, you will need to upgrade that ground wire (use a thicker wire with a smaller gauge). Otherwise, you will most likely experience noise even if all the cables are securely connected.
Concerning amplifier noise
Suppose you have placed your amplifier close to another device that emits some electrical signal. In that case, it is in your best interest to move your amplifier away from it.
In cases where you have an amplifier housed within a metal casing, then I recommend mounting it on a plastic or wooden (MDF) surface that will separate it from the rest of the vehicle.
What you could do here is construct or purchase a plastic amplifier rack or amplifier board.
However, if you are using a customized welded metal amp rack, what you could do to separate the frame from the rest of the vehicle is mount it to the car via rubber washes and other rubberized pieces of hardware.
Concerning signal connection cables
If you think that your signal connection cables could cause all your interference and noise, you have two options.
- If you have cheap, low-quality cables, replace them with some decent wires that come equipped with shielding. Wiring is relatively inexpensive, even for top-quality car audio wires.
- The other option is always to employ correct ca audio wire installation techniques. This means you would want to run the signal cables down the opposite side of your vehicle to your power cables.
Concerning speaker wire noise
If you unplug your speaker wire from your amplifier, turn it on and find that the noise is gone, then you will have two options, just as you did with signal cables.
If you have to have the power cables and the signal wires cross each other for whatever reason, it would best if they cross each other at a 90-degree angle to minimize the contact area.
One thing to note is that many people wonder if it is alright that when the power cables and signal cables get close to the amplifier, they will also get close to each other.
The answer to this is that it is okay because you should be running high-quality shielded signal cables.
Concerning aftermarket head units
If you are experiencing noise from your new aftermarket head unit, then a relatively inexpensive fix is extending the ground wire from the stereo to a reliable ground connection point in your vehicle.
Furthermore, when you purchase an aftermarket head unit, it should be apparent that it comes with an extended ground wire so that you can connect the wire to a relevant ground connection point in your vehicle.
Many factors should be considered when trying to establish what could be creating or contributing to noise within your car audio system.
Because we are dealing with an electrical circuit and many intricate components, there are many steps you have to take to ensure that noise or interference does not come into the equation. If it does, you need to use a process of elimination to figure out the cause of the noise.
Once you have determined what causes the noise, typically the fix is inexpensive.
However, it could be labor-intensive and time-consuming, like for example rewiring your entire system, laying the wires on opposite sides of the car, or constructing a rack made from plastic and remounting your amplifier.
If all else fails, you will need to take your vehicle to a car audio professional. More likely than not, they will be able to fix your sound, tune your audio system, and eliminate any noise or interference you may have. This option however, can be the most expensive one.