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alternator whine w/ iPod connected via Y-cable


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I have the aux-in version of the dual-HVAC-control head-unit. Aux-in is connected to a 3PDT switch which selects between two 3.5mm-1/8" minijacks (switch and jacks mounted in the upper cubby).


Sirius/XM is plugged into one minijack and it sounds fine. It's powered from a little PS I built at the back of the cubby, so very close to the minijacks.


With my iPod, pretty bad RPM-dependent whine (alternator I guess). The iPod is connected using a Y-cable that connects to a USB (for power) and the other minijack (for audio).


I'm thinking it's a ground loop, because (on the Y cable) the USB plugs into an adapter at the lighter outlet, pretty far from the cubby, and moving the cable around changes the noise from almost non-existent to really bad. Also, unplugging the USB makes it go away (but drops volume and iPod will go dead eventually).


I guess the common on the stereo jack is connected to ground. I could disconnect that, but then the return audio signal would go through the USB. Or disconnect the 5vdc ground, but then the audio common would have to carry the power current too.


Has anyone had much luck with these things for similar issues ?


Edited by RustyShackleford
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My buddy has this issue for a while, he ended up getting a generic usb powered bluetooth unit that plugs into the aux.

So, powered from USB, but sends audio via BT ? DIdn't know these HUs had BT capabilty.


Oh well, I bought one of those little thing that goes in the 1/8" cable (like the one I linked above), only $9, and we'll see how it works.

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