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Engine noise?

Discussion in 'Audio' started by madman, Mar 29, 2006.

  1. madman

    madman Registered Member

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    I need some help. I have really bad engine noise. I have a pair of 6X9s and 2 kicker 10s. kenwood deck and pioneer amp At first i had no noise. Then all of a sudden it started and kept getting worse. I checked my RCA cables and my power wire and remote to make sure they werent close together. All goodI think. I unplugged my amp and it still has the noise. So its is not the amp. I am going crazy trying to figure this thing out. I hope you all can help.
     
  2. Z3PR

    Z3PR Banned

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    Check all your grounds.
     
  3. tuffdogstudio

    tuffdogstudio 1/2 ton status

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  4. madman

    madman Registered Member

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    Thanks guys That is a alot of info on grounding loops. I will check all my grounds tommorrow. I hope that is all it is. I need some tunes. thanks again.
     
  5. chevyin

    chevyin 1/2 ton status

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    Run new power and ground wires to your deck (from the fuse panel and the nearest grounding spot). Ive found many stock wiring harnesses develope noises. The fact that it wasn't there to begin with, and has gotten steadily worse makes me think a bad ground also, and in the head if disconnecting the amp doesn't change it.
     
  6. AZ79K5Project

    AZ79K5Project 1/2 ton status

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    Your trigger wires are keyed and your constant power is going directly to battery (fused) correct?

    Run your constant power (pos/grnd) to battery. Don't run grounds to chassis. You will pick up noise.
     
  7. chevyin

    chevyin 1/2 ton status

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    Chassis ground is generally just fine, unless you create a ground loop situation. If chassis grounds were necessarily noisy by definition, you would need to run ground wires from every stereo component to the battery, and that's obviously not necessary.
     
  8. AZ79K5Project

    AZ79K5Project 1/2 ton status

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    Not completely true. The chassis ground is fine for non amplified signals. The amplifer will amplify ALL noise, including the noise from the other components. The best ground is at the battery.

    Medium and High end equipment ALL says not to connect to chassis. Run a dedicated ground to the battery as well as the +.
     
  9. chevyin

    chevyin 1/2 ton status

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    Actually, it is true, for the most part. ;) While running a ground wire back to the battery is the best solution for noise rejection (but generally not the best for resistance/voltage drop), it is not a necessity unless there is another problem. As a matter of fact, the better the amplifier, the less likely that a chassis ground will create noise. Here's what Richard Clark (considered one of the leading minds in car audio today) has to say on the subject:

    "the reason it's usually not a good idea to connect the amp to the cars metal chassis is that a lot of amps don't have good signal to supply ground isolation-------and if they lack good isolation they may not have good ground to case isolation---------and if thats the case there is a high possibility of noise------if you are confident that the amp has good isolation (AC isolation as measured with a bridge----not a VOM) it will not matter at all if you connect it to the chassis or anything else--------with good isolation it wouldn't even matter if you attached it to the positive battery post" - http://www.carsound.com/cgi-bin/UBB_CGI/ultimatebb.cgi?ubb=get_topic;f=1;t=020533

    Yes, if you create a ground loop situation, or mount your amplifier's chassis directly to the sheet metal, its likely to cause noise no matter how good your amp is, but that's an installation problem, not necessarily a grounding problem based on being to the chassis. A quality amplifier, mounted to a wooden/non-metalic amp rack, will negate much of the power supply to chassis isolation problems Richard was speaking of, and can be chassis grounded (most of the time).

    And, as the original poster said, when he disconnected the amp, the noise stayed. So we were talking about a low level signal issue. Also remember, the higher the signal voltage, the better the noise rejection (actually, the further the distance between the noise floor and the signal level, but that's a discussion for another day). Low level signals need more protection than do higher voltage signals. An amplifier will amplify noise introduced into the low-level signal (ie: RCA cables) just as much as it will the true signal material.

    JL Audio is the only large manufacturer I can think of off the top of my head that actually does recommend running a ground cable back to the battery. Im sure there are others, but its by no means the norm.

    I would recommend spending the time/money to run a ground cable back to the battery only after exhausting all other possibilities. Its certainly a possible problem, but by no means a necessity.

    Hope this helps. :)
     
    Last edited: Apr 9, 2006
  10. AZ79K5Project

    AZ79K5Project 1/2 ton status

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    Its been a while since I played with the stuff. :doah:Fosgate says not to run a dedicated ground longer than 30":rolleyes:

    chevin: Good catch :bow:
     
  11. chevyin

    chevyin 1/2 ton status

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    The reason they say to keep the ground wire less than 30" is for chassis grounds. They assume with chassis ground that there is a chassis contact point less than 30" from the amps, so anything longer is a waste. Basically they just mean dont run a 4 foot long ground cable, then ground it to your chassis... ground it as close as possible. This is of course because the longer the wire, the more unnecessary resistance that's added to the circuit. That's an example of a company recommending chassis ground, of course. But, JL Audio does recommend a ground cable back to the battery. After reading (and participating in) long debates about this (including with Manville Smith of JL), basically its came down to JL was covering their butt. They don't want someone to buy one of their ridiculously over-priced amplifiers and then get a ground noise problem due to a poor installation.

    The big debate on chassis grounding now isn't about noise, its about resistance. Either Richard Clark or David Navone (dont remember which right now) actually tested the resistance of chassis grounding to various late model vehicles and found their resistance foot prints to be highly varied. This is most likely due to the vehicle's design (full-frame vehicles versus uni-bodies, grounding methods employed by the various manufacturers, etc).

    Im certainly not against running a dedicated ground cable, as it can help with various problems that could arise. But like I said, its generally not necessary, and its definitely a more costly method than chassis grounds. Id do it if I cant get rid of a mysterious noise problem any other way, or if my chassis ground was causing a voltage drop issue. Otherwise, I wouldn't bother.

    Cheers.
     
  12. DEMON44

    DEMON44 Low-Tech Redneck

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    you check your alternator? Diode out on the bridge? capacitor NFG?
     
  13. madman

    madman Registered Member

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    thanks for all the info. I checked all my grounds looked goos and even ran new ones helped some. I did find a ground strap from the body to the back of the motor that was off and bolted it back up and the noise stopped. What ever it was it stopped. thanks again
     

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