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Ground loop isolator [message #86247] Tue, 03 October 2017 08:20 Go to next message
moss24 is currently offline  moss24
Messages: 107
Registered: May 2016
Viscount
How necessary is this when talking about a car audio system considering that a car's metal chassis will definitely have some resistance? How much would this cost on average?
Re: Ground loop isolator [message #86249 is a reply to message #86247] Tue, 03 October 2017 08:48 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17319
Registered: January 2001
Illuminati (33rd Degree)

Ground loops in cars are just like ground loops in homes. They're caused by resistance in the ground path.

An isolator is best used when it isn't possible or practical to use a single point ground. When two devices are physically distant, it becomes impossible to have the grounds at each end be the same. Each has its own ground. And if you try to tie the two together with a conductor, this makes things worse. This only creates two electrical paths - one through the earth and one through the second conductor. This leads to uneven current flow in the two paths, which is the very definition of a ground loop. In this case, the best approach is to use an isolator. Don't even try to connect the grounds together. Couple the signal a different way, like through an electromagnetic (transformer) or an opto-electronic isolator.

But in a car, the issue is much easier to solve by simply using a single point ground. The problem that usually presents itself in a car is power ground(s) connected to the chassis and sometimes additional ground connections made through an audio signal line. The audio signal could be a common ground speaker output or a preamp line level connection. If the chassis is connected to the battery at the engine and/or elsewhere at the front of the car, then there will be more resistance in the ground path when connection is made to the chassis at the rear of the car. This can cause a ground loop. The solution is to use good conductors that are large enough to offer low resistance and to connect all audio system grounds to the chassis at a single location.

Re: Ground loop isolator [message #86250 is a reply to message #86247] Tue, 03 October 2017 09:59 Go to previous message
drake is currently offline  drake
Messages: 197
Registered: June 2016
Master
At times I read such vivid explanations and wish I had pursued Physics further. All I can recall is that a good conductor is a substance with 3 or less electrons in its outer orbit. An insulator, on the other hand, normally has difficulty exchanging electrons because it contains 5 to 7 electrons in the outer orbit.
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