Alternator whine from Aux power jack in center console

J

Jax

Member
I've noticed that when I plug my Digital music player into the cigarette lighter that is located in the center storage compartment by the Aux/Music jack for the Bose sound system that there is Alternator whine.

On the other hand if I use the cigaretter lighter in the dash it works fine. So it looks like the aux power jack is not filterd. Has anyone else seen this? Since this was the main design usage for that power jack I was rather surprised to see this. Plan to bring it up on the next service check.
 
FWIW, no problem with mine. I have an IGO multi charger from Radio Shack charging my cellphone while the Ipod is running. Charger is plugged in to the power port next to the Aux jack. I haven't tried plugging in the IPOD power yet though. The ipod sits in the base of the center console plugged in to the audio input.
 
As long as the iPod isn't powered from the 12V jack, you won't get the ground loop that causes the noise. As soon as you try to power your iPod, you'll hear it.
 
I get the same thing. A background hiss when the Ipod is powered up, and it goes away as soon as I unplug the power.
 
yes-- it happens with mine on both jacks while charging/listening to my ipod (I've got the 6 cd/mp3 stereo- no Bose). Does anyone know if Mazda plans to fix this for us-- or are we sol?
 
omegamanha said:
yes-- it happens with mine on both jacks while charging/listening to my ipod (I've got the 6 cd/mp3 stereo- no Bose). Does anyone know if Mazda plans to fix this for us-- or are we sol?
Click to expand...

Mazda has no plans to fix this. I already suggested including a ground loop isolator as part of the Aux In circuit (would probably cost them less than $1) and was told that they would "pass the information along."
 
l-miwa said:
Mazda has no plans to fix this. I already suggested including a ground loop isolator as part of the Aux In circuit (would probably cost them less than $1) and was told that they would "pass the information along."
Click to expand...

Even my $70,000 VW Touareg has this problem. Solved it by spending $7.00 for a ground loop isolator. Stop moaning and just buy an isolator. My friend's Infiniti FX hums as well and we had to install isolators on the power lead and the audio jack.
 
jrtouareg said:
Even my $70,000 VW Touareg has this problem. Solved it by spending $7.00 for a ground loop isolator. Stop moaning and just buy an isolator. My friend's Infiniti FX hums as well and we had to install isolators on the power lead and the audio jack.
Click to expand...

Jrtoureg, you just don't get it. If a company makes a feature specifically for connecting aux audio components. They should make sure it works properly and doesn't adversely effect the sound quality.

Why couldn't Mazda or any other manufacture, have spent some additional effort to make sure this jack was already isolated so their buyers don't have to go buy additional hardware?
 
As consumers, we are forced to purchase not only the isolation transformer, but two jacks, cable, a case, and packaging to sell it in. Manufacturers would have to purchase only the isolation transformer. It just seems silly that manufacturers (not just Mazda) don't make this standard. I really can't imagine that it would cost them more than $1 to add it to the Aux circuit.
 
As all you guys know it is cigarette lighter so it did not need any filter as designed. It is a DC outlet like any AC outlet in any house so any device plugging in, they should need a filter for themselves. So I think the manufactures dont care to put a filter to those lighters.
I have no problem with my Sony MP3 and DVD player using genuine Sony cigarette power.
 
Last edited:
It isn't the power outlet that is the problem. It is the Aux In jack that needs to be isolated.
 
l-miwa said:
As long as the iPod isn't powered from the 12V jack, you won't get the ground loop that causes the noise. As soon as you try to power your iPod, you'll hear it.
Click to expand...
You said it's from 12V jack here!
 
nguvanh said:
You said it's from 12V jack here!
Click to expand...

Using the 12V power jack (either in the console or in the dash) causes a hum in the Aux In. Since you can't easily isolate the 12V jack, the usual solution is to use an isolator (basically a 1:1 transformer) to isolate the audio going into the Aux In jack. If you don't use the power jack, there is no ground loop to cause the hum.
 
nguvanh said:
Oh! the ground of lighter is different from ground of AUX?
Click to expand...

The problem is that the lighter ground and Aux In ground are connected through the audio system AND through the iPod, causing a loop. Since the audio circuits are relatively high impedance, any induced difference voltage (usually the alternator) causes a hum / whine.

The isolator electrically decouples the Aux In from the iPod, thereby breaking the loop. There's lots of info on the web about ground loops if you're interested.
 
If I was to cut and ground the Cigerette lighter somewhere metal under the center console would this eliminate the ground loop?
 
Unfortunately, it probably won't. The 12V jack just below the radio is just as bad as the one in the console.

If you need to power your iPod from a 12V jack, you should probably just get the ground loop isolator from Crutchfield. It works perfectly and sounds great.
 
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