Taking the Hum Out of Car Audio

For a long time, the missus and I have put up with various buzzing noises that come out of the car audio system in our Toyota Prius when we play media on our iPhones. It wasn’t until recently that I was annoyed enough to do something about it.

First, I had to discover the cause of the problem before I could do anything about it. Given that I am using a Kensington LiquidAux solution, I thought the Kensington website might be able to shed some light on it which turned out to be the case here.

Turns out that some cars either have inadequate grounding or a significant different in voltage drop at various  points of the car chassis. This results in a ground loop through the audio shielding which and is further worsened by the amplifier. The flow of current results in an audible buzz coming out of the car speakers.

So how do you stop it?

What you need is a ground loop isolator. Basically, you plug the output of the LiquidAux device into the input of the isolator then the output of the isolator into the auxiliary socket. The ground loop isolator breaks the earth between the devices which eliminates the hum. You can pick these up for about $10 on eBay or from stores like Jaycar.

You can also use a ground loop isolator in similar situations outside of the car where you have two devices plugged into different circuits instead of sharing the same circuit. At any rate, it’s a relatively cheap way to fix an issue that can detract from an enjoyable audio experience.

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