05-02-2013, 09:14 PM
Join Date: Mar 2009
Location: Georgetown, Guyana
Ben, I think you're a little off the mark - he's not streaming audio from the iphone, he's listening to FM radio.
pjf - I suspect the voltage regulation circuit in your USB outlet is what's causing your problem - the USB output is a 5V output so there has to be a circuit to drop the 12V from the car electricals down. I haven't used that style, but I have several of the ones that plug in to the cigarette lighter socket, and never experienced any issues with them - I don't think I've used an iPhone 4S specifically, but iPods, iPads, various other tablets and phones.
I was at one point looking for that style of USB charger so I could have a table connected and still have the cigarette lighter socket available (I usually have a little rechargeable flash light in there) but could not locate one that would provide the require 2A output.
Is the interference only on FM radio or does it also occur if you play a CD or listen to AM radio? I'm trying to determine what sort of interference is creating the noise - it could be as Ben has suggested being fed through the power wiring - however most car audio has input filters on the power supply to deal with that, my suspicion, especially if it's radio only is that the noise is being radiated from the device itself - you could try wrapping it in foil and grounding the foil - or maybe moving it further away from the JVC.
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