Strange Audio Noise

Discussion in 'OT Technology' started by jsiu, Apr 23, 2005.

  1. jsiu

    jsiu New Member

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    I recently installed a Pioneer DEH-P7700MP receiver unit and an Infinity Basslink into my '93 Toyota Celica GT-S with the System 10 (a factory premium stereo system option which includes 10 speakers and an amp). I previously had an old Sony headunit for about 3-4 years, but which was not connected to the System 10 (unlike most cars, there are 3 connectors in my stereo system: 2 connectors are for your typical wiring harness, the last one is for the System 10). I purchased a separate wiring harness which connects the left over System 10 connector to the receiver's pre-outs.

    Ever since I installed the Pioneer unit, I've noticed that I've been getting strange background audio noise no matter what source the music comes from (radio, CD, and auxiliary). There seems to be 2 different background noises. The first is a constant volume, constant pitch noise that sounds like radio static. The other is a high-pitched "whining" noise that usually increases in pitch as the rpms increase. So far, I've been drowning out the noises by playing my music louder, but when I want to lower the volume, it becomes rather annoying. If it helps, here's a timeline of my audio system:

    1) Stock System 10 - no whining noise
    2) Sony head unit without System 10 connected - no whining noise
    3) Pioneer head unit and Basslink without System 10 connected - no whining noise
    4) Pioneer head unit and Basslink with System 10 connected - whining noise present

    Is this occuring because my factory amp and the speakers it drives can't handle the higher voltages from the pre-outs (that is, it can't handle the cleaner signal)? Or perhaps, it's because they've been lying dormant for such a long period of time?

    Any help would be greatly appreciated. Thanks in advance.
     
  2. jsiu

    jsiu New Member

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    Anyone have any ideas?
     
  3. veonake

    veonake OnT poster, OT lurker

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    You have a ground loop problem. Is your ground cable for your amp connected to a good grounding point on the chassis with a very short cable run? Did you make sure to sand down to the bare metal? If you have a good ground on your amp, you could look into a filter for the problem.
     
  4. jsiu

    jsiu New Member

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    I don't think the grounding point is the issue. A multimeter reading confirmed this.

    I looked into a ground loop isolator and purchased one from Best Buy a few days ago. Unfortunately, after connecting it between the System 10 wiring harness RCAs and the head unit preouts, I am still getting the high-pitched noise. And It still increases in pitch with increasing rpm.

    The audio technician I spoke to at Best Buy told me that if the ground loop isolator didn't work, I could also look into a noise filter available at Radio Shack. Given this information, is there anything else any of you might be able to recommend? Thanks for your help.
     
    Last edited: Jun 6, 2005
  5. tryfuhl

    tryfuhl New Member

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    You have a ground issue whether you like it or not basically. What method did you use to determine that it was a good point? I'd measure several areas, and go with one of the points that comes out pretty much even to most of the others.

    Have any other electronics installed in the area?

    Ultimately you could end up running the ground wire back to the battery if it won't go away.
     
  6. jsiu

    jsiu New Member

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    Yeah, I've pretty much determined that I'm having grounding problems. I'll be adding additional grounds for the head unit and amp.

    There are no other additional electronics in the area.
     
  7. spooky

    spooky OT Supporter

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    i get the same noise. however it only happens to the speaker i connect to one of my two speaker connections on my amp, it also doesn't have much power to that side. so im guessing its a amp problem :dunno:
     
  8. jsiu

    jsiu New Member

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    From what I've gathered, if you're getting the high-pitched noise that increases in pitch with increasing rpm, then it's a ground loop issue or a grounding issue in general. I tried using a ground loop isolator between my amp and head unit preouts and that didn't solve my problem, so I'll try adding additional grounding points to see if that helps.
     
  9. spooky

    spooky OT Supporter

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    the sound only occurs at whichever speaker i connect at the left speaker connection at the amp. i switched the speakers around, and the noise will switch up...

    i bought a new amp for $100.. guess i'll find out where the problem is coming from soon.
     

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