Static from car speakers even when muted

A reader wrote us with the following question, “Why are my speakers producing static?” Because it’s such a common issue, we thought we’d share the solutions with the rest of the Electronic House audience.

Q. I recently purchased a pair of speakers that I use as my fronts, they sound great but sometimes I notice a static, fuzzy, cloudy, distortion sound. I tried 3 different receivers and still hear on occasion a fuzzy static sound, so I’m sure it is the speakers. I also moved the speakers away from my TV in case there was some signal problems, but no luck. What can be the problem? – Barry, Georgia

A. Bob Archer, Senior Editor, CE Pro, Dave Stevens of Steven’s Audio and Ric Johnson of Elite Systems Solutions weighed in on the issue.

Archer: 1. Try the speakers and your A/V receiver/amplifier in another room. I suspect what you may be hearing is a ground loop and it could be caused by some other component within the room.

2. Try another set of cables. Cables that aren’t properly shielded can act like antennas for RF (radio frequency) and EMI (electro-magnetic interference) noise.

3. You can step up your power conditioning with a product that offers isolation, surge protection and power conditioning. Look at products from Torus, SurgeX, Richard Gray’s and Furman and others. Tripp Lite also offers basic isolation transformers (a device that will isolate the components plugged into from the rest of the products plugged into the same circuit). A power conditioner from a company like Torus will run anywhere from about $1,500 to a few thousand. A basic Tripp Lite isolation transformer can be found for less than $200.

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Stevens: While I agree with Bob on all of the points he made, I would also take it a step further.

1. What is the brand of the speakers?

2. When you say “fronts,” are they your main front L/R speakers, or are they being used in addition to your front L/R mains for a “Height Channel” which some A/V receiver brands offer.

If they are your dedicated front L/R channels speakers in a 5.1 or 7.1 system, you more than likely have a defective driver in both. Most people believe that a speaker is blown when it no longer works. This is simply not true. A driver may be “stressed,” whereas it still works but will distort at a specific frequency and/or volume. Thus, the distortion you’re hearing is intermittent. Very common.

If they are additional “Height Channels” to your L/R mains, then there’s two ways to find out if it’s the speaker, ground loop, or the A/V receiver.

1. Connect the speakers by themselves into the main L/R outputs of your receiver. If they sound fine, then you know it’s not a problem with the speakers.

2. Take another pair of speakers, – for example, your existing rears – and hook them up to the same height channel outputs. Since you have no problem with your existing rear speakers, if they begin to distort on the same output, then you definitely have either an A/V receiver problem, or the other factors that Bob mentioned.

Johnson: I agree with Bob about the ground loop and with Dave about the testing. Since the static only is happening occasionally, what equipment is in use when this happens? Do you have a power conditioner in your rack and is it connected to a properly grounded electrical outlet?

Check the connections at the equipment end after you determine which pieces of equipment where in use that produced the static. Then make sure that the chassis earth ground wire is properly connected back to a good ground source.

Lastly, if the equipment connections look solid, do any of your wires run across an electric cord or wire, do any of them cross a metal duct, are any of them laying across any of the equipment? Another source of occasional static is harmonics that each piece of equipment sets up when operating. Properly dressing your cables away from electrical, mechanical interference may also help. Check each speaker cable for broken, cracked or damaged insulation.

Stevens: Adding to Ric’s post, (which I completely agree with), have you recently purchased a new refrigerator, wine cooler, or low voltage lighting that use dimmer switches? This goes to Ric’s post regarding a properly grounded and insulated AC outlet.

Anything with a compressor can wreak havoc with an A/V system every time the compressor turns on. Dimming switches on low voltage wiring systems also do the same thing, but you will hear the buzz become louder and softer as the switch is turned up or down.

I try to always play it safe and install a dedicated home run from the equipment to the main AC service panel.

The radio is, believe it or not, an integral part of the car; maybe it’s not as important as the engine or the suspension, but it’s definitely vital to people who need to take long drives. So, I always make sure that both my radio system and my speakers are in mint condition and working properly. And in all honesty, nothing is worse than having a set of speakers that make a lot of noise, especially if the car isn’t even running.

You probably came across this issue as well. For some reason, the speakers are giving off a weird sound, but the engine isn’t running, the battery is off, and you’re pretty sure you have everything hooked up properly. And while I did cover some speaker noise-related issues in the past, I think it’s time we looked into this noise problem in more detail.

Types of Noises Speakers Make

As we will see later, there are lots of potential sources for the speaker noise. So, in order to find these sources, you need to know your noises.

Generally, the unwanted speaker sounds, whether your car is on or off, fall into one of three categories:

Both hissing and buzzing are essentially static or white noise, depending on the intensity. Whining is a little less common than these two, at least when it comes to parked cars, but it still happens and it can vary in intensity.

Potential Speaker Noise Causes

Cars are complex and any little thing can set off a noise. Most of the time, you’ll need to consult an expert and let them diagnose the root problem, which can take a while. However, there are a few speaker noise causes that appear more frequently than others.

Grounding

Grounding is by far one of the most common reasons behind speaker noise when the power is off. If you didn’t fit the grounding wire properly, the speaker will make loud, hissing static sounds when it isn’t on. The same can happen if the wire you’re using for the grounding isn’t thick enough.

I should note that this issue is exclusive to cars that aren’t moving. During the drive, the grounding won’t make any noise.

Speaker Wires

Your car radio is connected to the speakers with a series of wires. If these wires are damaged, worn, or of poor quality, they can produce weird noises even when the car isn’t running. The radio has a constant power supply from the car battery, so as long as it’s hooked on and it has bad wiring, you can expect some noises to follow.

Radio Still Receiving Power

Some radios switch off the second you pull the key out of the ignition or power down the vehicle. However, there are radios out there that you can turn on at any point; these radios have constant access to a power source. Therefore, you can expect some static or whining with or without ignition.

Electrical Interference

Most of the causes I listed above are “internal”, so to speak. In other words, they mostly have to do with components that are already in your car. However, with electrical interference, the source of the noise issue is mostly external.

Let’s say that you want to plug something into your car’s USB port or an auxiliary port, e.g.,your cellphone, your MP3 player, a power cable, or anything similar. All of these external devices can either transmit or distort electrical signals. Said signals interfere with the sound that comes from your speakers, so it’s natural to hear some whining or buzzing during a drive. However, the noise from electrical interference can also come when the car is off, though it’s not that common.

Interestingly, your car speakers and stereo can suffer from electrical interference OUTSIDE of the car. To put it simply, any device powerful enough to emit electrical signals can have an effect on the audio equipment. This scenario is also one of the most annoying ones, since you can’t really do anything about it if the signal is coming, for example, from a power plant or an electrical installation in someone’s home.

How to Fix Speakers Making Noise When Car Is Off

In order to get rid of the noise when your car is idling in your garage, you’ll need to isolate where the noise is coming from. I suggest you do the following:

• Inspect the patch cables for any damages
• While playing the stereo, remove the receiver from the dashboard
• Disconnect the speaker wires from the amplifiers, then try switching the car off and look for the source of the noise
• Inspect both your car battery and your alternator
• Get a car noise filter or noise isolator if your engine is making the noise

Naturally, it would also be a good idea to check the speakers themselves. Any external damage to the speaker can cause the noise, so make sure to give them a thorough inspection; check everything, from the wiring to the cones. If all seems to be in order, proceed with the steps from the list above.

1. Check the Patch Cables

RCA patch cables tend to wear out, so it’s a good idea to test how they work. You do this by pulling one out and inserting a new, high-end cable in its place. Since there are usually multiple patch cables connected to the audio system, you might want to do this for each of them. After all, multiple cables can be out of order.

If you don’t hear any noise when performing this test, then the solution is simple. All you have to do is spend a few extra bucks to buy some high-end patch cables and replace the bad ones. I have to stress the “high-end” part, however; low-grade cables can produce noise even if they work properly, so make sure you focus on quality rather than price.

2. Disconnect the Wires

Poor shielding tends to be an issue with speaker wires. So, when you disconnect them from the amplifiers and hear no noise, you might need to use some magnetic shielding foil, or Mu-Metal. Wrap the shielding around the wires and try reconnecting them.

However, the issue with the speaker wires might not be related to the shielding. Sometimes, the wires might just be too close to other circuitry in your car. If that’s the case, simply try changing the position of the wires a bit.

Mu-Metal is also useful for stereos; when you remove the receiver from the dashboard and hook it up to play outside, it might play without any hissing or static. That’s your sign to use Mu-Metal shielding around the stereo itself before putting it back into the dashboard.

3. Battery and Alternator Issues

Usually, an alternator might whine when you drive or accelerate. But it’s still a good idea to have a mechanic look at it even if the whining noise is coming when the car isn’t moving.

Both the alternator and the car battery can generate electrical impulses that the speakers can pick up. And while a battery is easy enough to replace, with the alternator you’ll definitely need a mechanic. Have them tune your engine up and replace any faulty parts such as the spark plugs or their carbon-core wiring.

4. Solving the Grounding Issues

A typical grounding wire ought to be 18 inches long, at most. Any wire longer than that can produce noise. More importantly, it should be thick enough and be well connected to the amplifier. Loose or thin grounding will cause your speakers to hiss.

5. Noise Filters

I’ve run into more than a few mechanics who say that noise filters don’t really solve anything. In their words, it’s just putting a bandaid on an open wound. And while I do agree that you need to get rid of the problem outright, a noise filter is still a great temporary solution.

Most of the time, installing a noise filter is simple:

1. Insert the coaxial plug into your radio’s stereo socket
2. Connect the speaker’s RCA cables to the noise filter’s stereo socket
3. If necessary, get an adapter cable with one stereo plug and two RCA cable sockets

A Few Words at the End

Car stereo noise is bad enough when you’re driving, but it’s an absolute nightmare when your car is just sitting there with the ignition off. However, if you manage to isolate the problem, you can rest easy knowing that there are no weird buzzes or whines coming from your garage or driveway.

Was this article helpful and did you manage to get rid of speaker noise from your parked car? Please let me know in the comments below.

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