Buzz in Sound

djXternal · 10-13-2004, 01:08 PM

Hey Guys Just Recently Got My CarpC Installed...

Well now whenever i dont have ne music playing, but my speakers are turned on, i get a humming noise that increases in pitch according to engine rev... kinda entertainging sumtimes, but overall annoying

i was wonder what would be the best way to stop this interference? i have the line out cable going from my pc to another cable up front where it is then converted to rca plugs, which then goes to the AUX in on my HU

is it a problem with shielding or what?

nirvanades · 10-13-2004, 02:41 PM

Check out the grounding. You can also get a ground loop isolator - it is an interrupt that plugs in between your carputer and AUX unit. It will filter out most of what you are hearing.

hijinks21 · 10-13-2004, 02:44 PM

ya check your grounding.. ground your computer case and PSU to your car frame.. if you use an inverter ground that to the same spot

djXternal · 10-13-2004, 02:55 PM

ok right now, my screen is plugged into the cigarette lighter...
the HU is grounded to a metal post behind itself in the center console...
the inverter is running straight to the neg terminal on the battery...
and what is the best way to ground my PSU and PC??

I have the original PSU that came with my PC, and my PC components are mounted on a wooden board and housed in a fiberglass enclosure.

wyckyd · 10-13-2004, 03:10 PM

Ground EVERYTHING to the same spot...this will eliminate your ground loop (comes from having 2 or more grounding points). I had the same thing going in my blazer even though I had everything except HU going to a ground on the body in the cargo area; however, once I grounded everything to the battery I had no probs.

falconey · 10-13-2004, 03:18 PM

Quote: Originally Posted by wyckyd

Ground EVERYTHING to the same spot...this will eliminate your ground loop (comes from having 2 or more grounding points). I had the same thing going in my blazer even though I had everything except HU going to a ground on the body in the cargo area; however, once I grounded everything to the battery I had no probs.

This proves a point I've tried to make time after time. You only should ground major components together. You shouldn't ground two components together that have huge variations in current draw unless of course you ground to the battery. I say don't ground to the battery and just find a better spot to ground. Grouding to the battery increases the amount distance the current must flow although wyckyd seems to have done it with positive results.

hijinks21 · 10-13-2004, 03:52 PM

don't ground your inverter back to your battery. ground it to the car frame.. then ground the screw that holds in your computer PSU to the same spot.. that alone should kill all if not most of the noise.. your ground should never run back to your battery.. generally they should stay under a foot long

nirvanades · 10-13-2004, 03:55 PM

I agree with hijinks - ground your inverter close to itself... Find a bolt, something that you can use... Short grounds are important.

hijinks21 · 10-13-2004, 03:59 PM

opps forgot to mention your other question.. you can get like a oring connector at radio shack.. attach some wire to it.. and the oring part just goes around the screw.. tighten the screw and do the same for the other end on the same screw you ground your inverter to

teamwork1999 · 10-13-2004, 09:31 PM

I have a similar problem..the only thins is that my audio is not hard wired because i don't know how to do it...i am searching the net right now to learn how to do it...but i haven't been succesful...right now i am using an fm modulator to get sound from my computer to my car speaker and i have a similar problem, i hear the buzzing of the engine on my speaker plus the interference that comes by using the fm modulator...i will try to ground my unit tomorrow (if you guys check out my car pc you'll see that it's a pain in the *** http://home.earthlink.net/~teamwork1...ge/good%20pic/) to see if that helps with the buzzing...also does anybody know a good guide on how to hard wire the audio to the car speaker..i have a 2003 land rover freelander
thanx

djXternal · 10-13-2004, 10:14 PM

After i grounded my PSu on my PC, it cut the sound in half, so i cant hear it nemore, unless no music is playing and i turn my stereo up

Mr Crown · 10-13-2004, 10:36 PM

Your problem is on your Hi impedance signal generation/transmission (before or inside your amps).

Try this:

Turn on your complete system. Take some signal source (CDplayer, walkman, fmradio), POWERED BY BATTERIES, not your car battery, and feed your amps, THRU YOUR ACTUAL SIGNAL CABLES, make stereo tests for each pair of amp inputs.

Is there noise? is only on some channels? Just work with channels having noise.

NO==> your problem is on your signal generation. Try other hardware. Dont have enough info to help you. Dont think this is your case. Sound cards tipically have good PS ripple rejection.

YES==>Try connecting the signal source directly to your amps.

Is there noise? NO?==> your cables YES==> your amps.

If the problem are your cables:

Your signal cables are working as an antenna for the noise, and inducing it on your amp inputs.

After checking/changing any loose connection and separating signal cables from power cables.Try this:

HEY CHECK FOR LOOSE CONNECTIONS.

1.Not common ground between your amps inputs and output of signal gen device. This is: for 4 channels just run 4 wires (running just the signal), not 8 running the signals and respective grounds.

Not worked?? Try this:

2.Run twisted pairs for your signals cables: buy some cat5 utp cable (Ethernet networking cable, patch cable)from any store, you have 4 pairs, ready to run 4 signals RUN EACH SIGNAL WITH ITS RESPECTIVE GROUND ON EACH TWISTED PAIR. You're doing nothing if dont do itthat way.

Not worked?? (are you near any radio/tv/telecom station?) Try this:

3.Temporarily try running the signal on tv antenna coaxial cable. EXTREEEM SOLUTION, dont think you need to buy coaxial cable to run your signal but if the problem is inducing noise and the failed the tries before, this should correct it.

If the problem are your amps:

Maybe need repair or change if it is/are new. It shouldnt make noise just for the input. Unplug any input cable, set max volume, you should hear the noise. No? maybe your problem are your cables you forgot some loose connection.

Hope this help men. Post more info. LOT OF INFO.

djXternal · 10-13-2004, 10:49 PM

well as i had previously said... my problem was mainly with mot having my PSU grounded... i may fidget here and there with completely eliminating the sound, but i can no longer hear it unless i try to get the sound to go through the speakers, but other than that im fine with this small amount of noise

Mr Crown · 10-13-2004, 10:55 PM

It seems like your PSU is not good rejecting ripple. Try grounding the chasis, and running your audio signal cables without ground.

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