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I am busy installing sound in my car. I have installed an amp and have VCC running to the battery and ground connected to the body of the car. I have noticed that there is noise, seems to be a high frequency noise, that is produced when the amp is on. The pitch of the noise increases when I accelerate (this is quite annoying). This noise did not happen when I didn't have an amp so I'm assuming its the way I have connected the amp. I would like to know if this is a common problem and any suggestions on how to fix it would be appreciated.

Extra: after connecting my amp my radio reception is terrible, I noticed that my aerial is also grounded to the body so I'm wondering if the amp could be affecting the aerial.

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closed as off-topic by JYelton, Anindo Ghosh, Dave Tweed, Matt Young, Scott Seidman Aug 29 '13 at 18:22

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions on the use of electronic devices are off-topic as this site is intended specifically for questions on electronics design." – Anindo Ghosh, Dave Tweed, Matt Young, Scott Seidman
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This question appears to be off-topic because it is not about electronic design. –  JYelton Aug 29 '13 at 5:18
    
Keagan, sorry, this might be border-line, because it is still a common electronics engineering problem. –  JYelton Aug 29 '13 at 5:19
    
I apologise for posting in the wrong place but I thought this was a common electronics problem. Im only 1st year electronics engineering so I dont know THAT much about electronics yet. –  Keagan Ladds Aug 29 '13 at 5:32
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If it helps any, you might like the Crutchfield guide to car amp noise problems or noise suppression guide. –  JYelton Aug 29 '13 at 5:41
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1 Answer 1

Sounds like you have some suspect wiring and/or less than brilliant electrical systems in your car. The amplifier is highlighting it as you're boosting the small signals a lot more. It's also probable that it does not have very good EMI protection, compared to the OE head unit which has the advantage of knowing exactly how bad the system is going to be.

User28161 missed a major source of the high-pitched whine which is your vehicle's alternator.

First step would be to look at suppression, these problems are as old as the car radio and are very well documented so I won't go into the detail other than to suggest googling & reading up on it.

If you have access to an oscilloscope you may be able to trace the noise back through the system to find out where it's being introduced.

Using good heavy cables for the wiring, and connecting the negative direct to the battery terminal rather than just grounding to the bodywork (copper is a better conductor than steel, your car's bodywork is not designed to be an electrically efficient path, there are spot welds, paint, possibly corrosion...).

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I can confirm that the alternator and/or ignition system is a huge noise source. It gets everywhere in a car, and is often common-mode too. If I'm charging my MP3 player, and have it plugged into the line-in on my head-unit, I get a distinct whining that varies depending on the engine speed. The solution is something that breaks the common-mode noise, e.g. an audio isolation transformer. –  Connor Wolf Aug 29 '13 at 8:45
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