FAQ: Getting Rid of that Whine or Buzzing Noise in Your Speakers

Bugbyte · 05-31-2005, 07:51 PM

So, now you've installed your PC and hooked it up to your stereo. It rocks! Except for the fact that there's this "buzzing" noise, or "whine" coming through your speakers! It may seem to pick up when you accelerate and slow down when your rpms go down, or it may just be a persistent buzzing noise. Either way, it's ruining your install! What's up and how do you get rid of it?!

The noise is nearly always caused by improper grounding of your system. According to the wikipedia, a ground loop is caused by an unwanted current that flows between a conductor at two points that have nominally the same potential.

Wha?! Here's what's happening. The chassis of your car serves as a ground. Often when installing PC's and amplifiers, they are located in different parts of the car. The ground wire for both units is often grounded in different spots on the car. While the metal chassis is a decent conductor, it isn't perfect and there can be a difference in electrical potential between the two grounding points. The result is a buzzing noise, or a whine, often coming from the alternator, which accounts for the change in the sound as the alternator spins faster and slower with engine rpms.

There are two possible solutions:

1. Ground all components to the same point. This will reduce the potential and should greatly reduce any noise.

2. If number 1 is not possible (and it often is not), use a "ground loop isolator", available at nearly all electronics stores, or car audio suppliers. This device prevents a direct electrical connection between the two sources and will usually fix the ground loop.

The source of the whine can be mysterious and very difficult to track down even if you perform 1 & 2, above.

For more information, search on terms: "Ground loop", "alternator whine", or "buzzing".

Useful threads:

http://www.mp3car.com/vbulletin/show...ht=ground+loop
http://www.mp3car.com/vbulletin/show...ht=ground+loop
http://www.mp3car.com/vbulletin/show...ht=ground+loop
http://www.mp3car.com/vbulletin/show...ht=ground+loop
http://www.mp3car.com/vbulletin/show...ht=ground+loop

Car audio professionals/geniuses, please post any tips or tricks in this thread. Thanks!

Stealth97 · 06-05-2005, 12:52 AM

Also, a loose audio connection between your PC and amp, or PC, head unit, and amp (depending on your install) can cause a constant buzzing sound. Often the Y-adapter connecting the sound card is not pushed in fully. That one has bitten me several times.

crypto · 06-06-2005, 06:08 PM

or you can get the ground straight from the battery... run two wires from the battery (pos and neg) instead of one(pos)...i know you can get the ground from the chassis but its better if you get it straight from the battery terminal...
just my 2 cents

shakes · 06-07-2005, 04:18 PM

As an added note, in a CarPC setup sometimes buzz or hum can come from an unmuted MIC or Line-In on your sound card. this has been happening to me lately.

Another thing bugbyte probably meant to mention, is make sure your groud points are clean. That means sand/grind off all paint and such so you get a clean metal on metal connection.

Regarding grounding to the battery ... I've always heard and read it's better to keep your ground cables as short as possible. YMMV ... so if they're long and you get no noise more power to ya.

Yuriy · 07-07-2005, 02:07 AM

I recently discovered than background noise can get higher in volume substantially if your battery is low. In my case, to drive my three 12" woofers I require more current than the alternator can provide, therefore my battery eventually discharges and needs manual charging. I noticed that when it's very low, the whining noise is simply horrible to a point where you can't hear anything. But as soon as the battery is charged to 50% or above the noise is removed completely.

Levin · 07-09-2005, 03:28 AM

It's also possible that the RCA cables are too close to power cables. While most proper setups would ensure that power cables do not run near or beside audio cables, people make mistakes...like me. I solved it by moving the power cables further until there was no more "whine".

Bugbyte · 07-09-2005, 10:18 AM

I too had a slight whine upon finishing my install. Rerouting my audio wires away from my power wires (they were carried in a common wire bundle) made a huge difference.

KyleYankan · 07-10-2005, 12:45 AM

same for my install - power wires down other side got rid of all of it

carabuser · 07-10-2005, 05:00 PM

Getting Rid of noise using POWER INVERTER:
The main idea: ground EVERYTHING POSSIBLE that runs from the inverter.

My experience: Using a laptop and Lilliput 7" both powered by an inverter (from sig. lighter). A lot of noise in the speakers, a lot of noise on the screen as well.
Solution:
1. Grouning the screen (yes, screen does make noise): simply take the negative line from the screen's power adapter and ground it.
2. Grounding the laptop: same thing, take the negative line from the laptop power adapter and ground it to the chassis.

My two grounding points for laptop and screen are at two different locations but there's NO noise when the system is on.

However, there's still loud noise when I turn the laptop off.

EDIT: This might sound stupid to those of you who's been in "business" for a while, but I'm sure people with less experience can use it: use HIGH quality cables. In my case I'm using a cheap radioshack cable to connect laptop to my HU and over time quality went down and I can hear a lot of noise now.

Yuriy · 07-11-2005, 09:08 AM

Funny how electronics work, when I turn on my inverter 80% of the noise goes away.
That's not saying that I have a lot of noise, and have almost zero, but whatever's there, it goes away when I switch the inverter on. That's a complete opposite of my last system, where turning on the inverter means you'd be listening to your alternator instead of MP3s.

KyferEz · 09-04-2005, 07:44 AM

A little more info about grounding...

It's not always a good idea to ground directly to the battery, as long lengths of wire can be the cause of ground loops as well, as previously stated. If you make sure you have a heavy grounding wire (4gauge or larger) from the - terminal of the battery to the vehicle's body, then most often grounding to the body of the car will be fine. However, there will be noisier ground spots on certain locations of the body than others, and these locations are different for each and every car.

Also, grounding everything to the same ground point may not be necessary, and may even make the situation worse, depending upon the gauge of wire used and if the 1 ground point you choose was already a noisy location because of all the other ground currents flowing around your vehicle.

The BEST thing to do is try each and every suggestion you can find and see which works best for your particular vehicle/setup. (Or at least try them until you find one that you can live with.

KyferEz

attack eagle · 10-01-2005, 01:27 PM

if you are adding big loads or long runs, please consider upgrading the chassis to battery ground to 2ga...

another thing is that with many electronic devices like amplifiers and other metal cased devices the outside shell is ground. Avoid if possible screwing and in essence direct grounding them. For some reason they will give you noise if they are grounded thru the chassis instead of thru the ground wire.

mount them isolated, using a wood block or plastic to electically isolate the chassis from chassis.

Ever since i started doing this 8 years ago I have never had a single alternator whine problem in any install. Example, in my current car I have 2 ga power, changer cables speaker cables and 3 sets of rcas bundled together, and in my mgb after adding a bigger ground for the dual batteries, and isolating the amps and crossovers by building a trunk board all noise was eliminated, and that was a noisy little car to begin with.

12Vsystems · 11-02-2005, 05:38 PM

In the past I have had problems when running cables near the air condition. Everything sounds great until I turn the A/C on then I get a buzz. Rerouting the cables away from the A/C solves the problem.

carabuser · 11-02-2005, 05:55 PM

Quote: Originally Posted by 12Vsystems

In the past I have had problems when running cables near the air condition. Everything sounds great until I turn the A/C on then I get a buzz. Rerouting the cables away from the A/C solves the problem.

I have/had very similar problems. Same thing happens with rear window defroster.

anky1 · 11-03-2005, 01:03 AM

http://www.termpro.com/articles/noise.html

older article but always a good start.