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".
Buzzing noise help
HOW TO: Get sound from PC to Car Stereo / Amp
Some strange noise...
Red Red Whine....
Whine with a twist
Car audio professionals/geniuses, please post any tips or tricks in this thread. Thanks!
Is this where the witty comment goes?97 Black pearl Mazda Miata MX-5 Carpc V2? maybee..
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
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.
My JeepPC Install
"there are no stupid questions, just stupid people."
"it's been agreed the whole world stinks so no one's taking showers anymore"
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.
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".
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.
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.
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.
Current Status: For Sale
- 1.5Ghz Toshiba Laptop (available - no screen)
- Indash Motorized 7" VGA TS
- DeLorme GPS (sold)
- Power Inverter (sold)
- Pioneer HU (sold)
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.