Hey guys, I know this has been brought up before but I kinda forgot what caused it besides the alternator. Basically, I have a MP3 player in my car. Now I can hear a very loud alternator whine. How can I get rid of this? My PC is in the passenger seat right now. If I move it to the back will that help? The plug is also not the greatest, it is a headphone like jack to RCA, then a double female connector, and then another of the same going the opposite way. It was basiclly how I got the cord to be long enough....
Thanks,
Douglas

 

Your PC is in the pass seat? Are you using an inverter to power it or is it a laptop running off batts?

Remember, everytime you use a connector, your increasing the chance of noise, esp with cheap components. And the sig-noise ratio of most PC sound cards is not very good.

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-Justin-
T-Top '86 5.0L LG4 700R4 WS6 Now Bilstein equipped!
T-Top '92 5.0L TBI 700R4
My '86 Firebird Homepage
The F-body Model Kit Pictoral Archive (updated 9/18/00)

There can be only one!!

 

Yeah, it is kinda a full size PC running off of an invertor. I just kinda tossed it in there. Okay, so would it get better of I found a double ended headphone style jack cord? I didn't use a cheap connector, it is a gold plated one.
Thanks,
Douglas

 

I would bet its the invertor doing it. Try this. Dont plug in the invertor. Plug the PC into an extension cord plugged into your house. see if noise goes away.

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-Justin-
T-Top '86 5.0L LG4 700R4 WS6 Now Bilstein equipped!
T-Top '92 5.0L TBI 700R4
My '86 Firebird Homepage
The F-body Model Kit Pictoral Archive (updated 9/18/00)

There can be only one!!

 

I bet its not, and here is the reason. The whines pitch is directly variable to engine RPMs. The higher the RPMs the higher the pitch. I doubt the invertor is changing its sine wave (what would cause a hiss according to their book) by how much power it is getting considering it is always getting between 11 and 14 volts, which is where it operates optimally.
This wasn't supposed to be a complicated question as it has been asked before and it has been alternator whine, I just forgot what forces cause it and how to fix it. This is a basic stereo setup, forget I have everything but a basic stereo and I say that I have a whine thats pitch goes up as RPMs go up...
Thanks,
Douglas

 

Sorry, but it's really not all that easy! I do suggest that you try what has been suggested about eliminating the possibilty of it being the inverter. I don't have any experience with invertors, but I'm sure that they aren't the cleanest power anyway!

The noise from the alternator is always there no matter what. You typically have to rely on the stereo components to filter it out properly. Maybe the inverter doesn't have anything to filter out the alt. noise?

There are some aftermarket filters out there that you can try. I know radio shack carries some, and maybe a car audio shop would also.

Good luck, the altermator whine is very difficult to get rid of!

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Working on:
'84 Z28 LG4 305
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350
using primarily GMPP parts.
Block is in shop!

Starting to look like the Kicker poster child!

 

Answering your questi0on abou the alternator whine...what causes it is the electro magnetic fields assosciated with the whole electricity thing bleeding into other wires. The main problem hat causes this in most car stereo installs are the RCA's (though a good set will be heavily shielded to prevent just that), or unshielded speaker wires coming into a close proximity with a "power line". That why on installs you will always see the power wires run on one side of the car, and lines transferring signal's on the other side. So most likely, somewhere in your setup, youve got a signal picking up distortion from one of your power wires. Either change to a well shielded wire, or rerun the culpret wire along another route to avoid the contact.
Ummm...can you post a picture of your setup? You've really got my curiosity up with this whole computer, inverter, MP3 thing. Being an amatuer installer and a PC/Network tech...I'm quite interested to see what you've got...it sounds pretty sweet.

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'87 GTA
Automatic 350 TPI
2 3/4" Flowmasters
K&N filtercharger
4 3/4" Glasstech Cowl induction hood
TPI intake air foil

Planed mods:
10 bolt rear end-3.73 posi- next week
6 speed manual trans.-next month
383 stroker...maybe

 

Okay, thank you for the replies. I kinda am thinking it is my sound card acting like a antenna that is picking up the alternator whine, or maybe the unshielded cables I am using. It whines like that before the music starts playing, so I am kinda thinking it is the wires, probably it is so bad because I have totally unshielded parts on the wire (like bare metal showing). I guess I need to try and move that as far away from everything as I can get, huh?
As for pictures, yeah, I'll take some, but not until the setup looks descent. Right now all it is is a PC box sitting in my passenger seat w/ a plug going into the stereo and the power invertor plugged into the cig lighter.
And as for the invertor being clean, no the power isn't very clean, it does state that on cheaper stereos/boom boxes there might be a hiss due to the bad power, but I figured my PCs power supply would clean it up a lot and it wouldn't come out through the speakers.
Thanks,
Douglas

 

There is another system configuration that will cause alternator & ignition noise to be injected into the audio system. If the ground wires of the head unit, amp, crossover, etc. are not connected to one common point - usually on the chassis - then a ground loop will be created - current flows through the shields of the audio cables, instead if the ground wire. The chassis of all of the individual components must be floating (chassis ungrounded), as well. Use heavy gauge wire to ground amps, & head units that drive speaker outputs. Simply grounding each component to different locations on the chassis will make it necessary to use isolation transformers in the audio lines to break the ground loops. If a ground loop is causing the noise, unplugging the audio cables will make the noise go away. If noise is present with the audio cables disconnected, a power supply filter, or filters, may be necessary. Alternator noise may be isolated by unplugging the alternator & running the engine - if the noise remains and varies with engine RPM, it's most likely ignition noise, or a combination of both sources.

Tim

 

Are you telling me that your driving around with a computer sitting in the passenger seat next to you? Hahahaha thats some funny ****. Wouldn't it be cheaper to just buy a mp3 stereo for your car? Your computer has to worth more than 700 right?

 

Yeah, well, I relocated it to the backseat because my girlfriend is more important then the PC. And no, not even close! First, the computer is totally more versatile then the MP3 player head unit. Second, I don't want a MP3 player headunit, they are a great idea but I want a DVD player, music video player, Playstation, etc and the computer is great for the DVD player, MP3 player and music video player!
I have paid in total about 80 dollars for stuff. I paid 40 for the power invertor, 21 for the LCD screen, and another stuff was about 19-20 bucks! 700 for the PC system, you have got to be kidding!!