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Sevnn
Candy Cane King
Joined: 22 Mar 2003
Posts: 7711
Location: Kyrat
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Any type of isolator is like a band aid for a bullet wound. It might keep the blood from coming out but does nothing to solve the actual problem. Low hums are usually caused by your RCAs being too close to a noise generating device. In home and business audio, this is often caused by cables going near fluorescent lights. In cars the source is a bit harder to find but look for things that generate radio signals.
Alternator whine is almost always a ground loop. What that means is the electrical device on one end of a signal path (head unit, preamp, amplifier) is improperly grounded and "pulls" ground from the device it is connected to. This brings the ground flow through the RCA and subjects the cable to the noise generation of the ground through the entire length of the cable. This is most often solved by checking the ground of all devices in your audio system, verifying the ground of the vehicle is sufficient, adding more ground to the vehicle, and replacing poor performing audio devices. Ground loop isolators can "fix" the noise but don't solve the problem. The device is still improperly grounded, they just cover up the electrical interference.
I've only worked on one car in my 7 year car audio career that had unsolvable ground noise problems, and I am still convinced I could have fixed it if the customer would have allowed us to keep working on it. I even donated my time because it was such a great challenge but I think I got enough of it out that he was happy. It was an older MR2 (like my blue one) and I'm fairly convinced it was a bad alternator voltage regulator. I wasn't going to replace that piece but adding more ground paths from the alternator/engine to the chassis could have helped.
Sorry to derail, just trying to make the point that your noise problems are solvable without isolators. Go through all the grounds on your equipment first. Make sure they are screwed to actual metal, not to painted metal. Remove paint if necessary. Make sure the metal they are screwed to is properly connected to the body. Thinking of this really quick, try a long piece of 14 gauge wire, connect it to the negative battery terminal, then touch it to the grounds for all your equipment. When the noise goes away, you found the unit with the bad ground.
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Sun Dec 09, 2012 4:29 pm
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