ideas to get rid of engine noise.
#31
A resistance test is absolutely meaningless. A multimeter sends out millivolts and milliamps as test current. Poor connections, or connections that will not actually pass large amounts of current will not be found this way. I promise you that a joint that reads 0.0 ohms with a multimeter will read something very different at 50, 75 or 100 amps.
DC is not like AC at all. AC will often bridge a poor connection, but DC will not. Even at lower currents, DC will cause a poor joint to heat up, and increse it's ESR quite substantially.
The only 100% guaranteed good ground you will ever have is to have both positive and negative lines run all the way back to their source, both battery and alternator. Anything less and you're banking on a the quality of another's job that really we have no idea how good it is, until there is a problem to fix.
Current flows down the path of least resistance. If you have 14.4V potential to ground at your deck, but you are getting 13.5V at your amp due to current draw, porr gorund or inability of your chosen ground path to pass current, you are going to get circulation of current and voltage along the RCA lines. As RCAs are passing AC, this is where your AC ripple from your alternator is likely to pass. And that 0.9v difference may be more than the signal your deck is producing. The effect of this would be noise in the extreme, but most guys don't have that problem, their problem is more in the microvolt range, but still enough to be annoying. This is why grounding the RCAs can be effective, but not always, to remove any stray voltage on the RCAs between components. This is a "ground loop" and the reason "ground loop isolators" work is to break this physical link with a 1:1 step transformer.
DC is not like AC at all. AC will often bridge a poor connection, but DC will not. Even at lower currents, DC will cause a poor joint to heat up, and increse it's ESR quite substantially.
The only 100% guaranteed good ground you will ever have is to have both positive and negative lines run all the way back to their source, both battery and alternator. Anything less and you're banking on a the quality of another's job that really we have no idea how good it is, until there is a problem to fix.
Current flows down the path of least resistance. If you have 14.4V potential to ground at your deck, but you are getting 13.5V at your amp due to current draw, porr gorund or inability of your chosen ground path to pass current, you are going to get circulation of current and voltage along the RCA lines. As RCAs are passing AC, this is where your AC ripple from your alternator is likely to pass. And that 0.9v difference may be more than the signal your deck is producing. The effect of this would be noise in the extreme, but most guys don't have that problem, their problem is more in the microvolt range, but still enough to be annoying. This is why grounding the RCAs can be effective, but not always, to remove any stray voltage on the RCAs between components. This is a "ground loop" and the reason "ground loop isolators" work is to break this physical link with a 1:1 step transformer.
P.S. I went back to check for voltage drop on my car and the voltage at my battery and my amp are the same. You brought up a good point,so maybe i got lucky.I think I'll check out more cars as I get a chance to validate my theory that shorter is better.
#32
All cars these days us a minimum of welds, and very often use non-conductive adhesives. Techniques to remove noise are better than buying and isolator to the job, especially on the signal path. Ground loop isolators were notoriously bad for frequency response.
Fix the problem, don't try to mask it.
Fix the problem, don't try to mask it.
#33
this turned into a full out battle of the n0ise reduction techniques hahahaha.
thanks for all the help guys.
i wont be buyying a ground loop isolator because i have already spent enough money and dont want to spend any more on something that may or may not work.
but there is still taht last little hiss . i think the only thing i havent tried it to reground my alternator to the chassis (same place as the battery will be grounded to chassis) i guess when i get time i will try that. and hope that i have enough 0 gauge left to run that. since i have very little left.
thanks for all the help guys.
i wont be buyying a ground loop isolator because i have already spent enough money and dont want to spend any more on something that may or may not work.
but there is still taht last little hiss . i think the only thing i havent tried it to reground my alternator to the chassis (same place as the battery will be grounded to chassis) i guess when i get time i will try that. and hope that i have enough 0 gauge left to run that. since i have very little left.
#35
haha ya. well i do all my install with a little help on the idea side from my buddy installer. but i have been the only one to ever touch my car. umm as for the resistance change i have not even checked it out. lol ..
i have just been working on finishing before school. and also this last bit of noise which i will try the 0 gauge ground to the alternator.
i have just been working on finishing before school. and also this last bit of noise which i will try the 0 gauge ground to the alternator.
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