So I spent a couple hours yesterday troubleshooting this buzzing noise. It's a noise which is present in my carputer setup, EVEN WHEN MY CARPUTER ISN'T EVEN ON. It just has to be plugged in and receiving power (completing the circuit from the noise source (I'm guessing something in my car? ignition?) to the amp to the speakers (and you can hear it)).
This is what I've found:
* It's a buzzing sound, very faint, but gets louder as I increase my amp gains (so it's pre-amp noise)
* It goes away when I put on my LPF on my amp, so it's above 250Hz somewhere
* It doesn't seem audible when I turn my ignition to ACC, until I press the door lock (lock or unlock) button, then I can hear it, so it seems somehow tied to the doors and their electrical layout
I'm still not 100% certain it is not the PSU. I've heard PSUs can produce a slight buzzing.
Still left to do:
1. I need to pull the PSU and/or motherboard from the case and hook them up to the system w/out the case and see if it still occurs -- if it's the PSU, it could be that it was making noise into the PC case which then made it's way into the motherboard or something like that.
2. I need to try powering the PC from another car/battery, and see if it still does the same thing (then I'll know if it's my car or if it's my PC).
3. Any other ideas??
I could really use an oscilliscope to help find what freq. this buzzing is at or ranging around..
If you can hear it while driving down the road and have the volume on 1 (or the next to lowest setting) and it gets a higher pitch when you step on the gas or kinda makes a ticking noise with your blinker then there is an easy answer: Ground loop. Ground everything to the same place to fix it. If your computer is grounded in the back of your car and everything else is up front, then that is your problem, at least it was mine.
Try this to make sure:
Route + and - wires to the terminals on the battery up front (no need to hide wires just hang them outside the car - you won't need to leave your driveway/parking space/garage). Turn your car on and try turning the volume down, step on the gas, turn up your gains, or whatever to see if it is still going. If not...ground loop is the problem, hide the wires inside you car.
Also make sure your current power wire is not running close to ANY RCA cables or your exhaust manifold.
This has been a struggle for everyone. The best idea is to check your grounds. Use equally as thick cable as you do for you power or hot wire. Use thick enough wire for you hot wire, 10 gauge reccommended or larger. Use quality cables. Try using an amplifier wiring kit, they usually come with pretty good wires. If the problem still persists, check your cooling fans. I have notice the noisier fans you have the bigger of a problem you have. Also check in to using noise filters, they do work.
Just my FYI for the NOOB
You can still have something if you have nothing