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You must remove the GROUND connection on your car charger, the easiest way is to cover the two prongs at either side of the cigarette lighter jack in black electrical tape and leave the centre pin in place.
The signal ground for the Audio will become the ground for the charger and the amplifier in the CLIP+ will stop ground-loop oscillating.
I know it works because my car is hooked up that way right now. You can test this theory by running the player, plugged into the charger by USB and then just touch the ground connection on the charger to the ground ring of the cigarette socket; instantly the audio dies.
Bizarre design flaw in the CLIP+ and an even weirder workaround, but I've been using the player this way for several months now, no damage to the player or the head unit.
The problem with this reasoning is that the clip+ headphone ground isn't actually connected to the power ground. Its hooked up to an active common ground which is biased above power ground. Looking at the datasheet it apparently has an overcurrent protection that kicks in at 300mA, so presumably a current under that won't damage it, but I'm not sure I would recommend trying this. You certainly risk burning out the player's amplifier by driving quite a lot of current through it.
Thats probably the overcurrent protection kicking in to prevent you from blowing up the amp. Did you actually try charging the clip+ that way, or was this with a different player?
A ground loop generally happens because the stereo is wired up properly to the car battery.
It would probably be better to use a ground loop isolator on the audio output and leave the player powered properly.
Why would there be an over-current when the player is being charged from USB?
It charges and plays fine when powered from a laptop with USB that's separate from the car, just not while output and power are connected to the same car.
I've charged the CLIP+ like this (with p/gnd disconnected) for several months now and listened to it in car while it's running with no problems at all. If it's over-current protection, it's not very good because the player will still function and play, but the audio sounds like mince while there are two grounds connected.And what good is a design that overcurrents when it's correctly connected anyway? Lol!
Quote from: TurboZutek on April 01, 2012, 05:24:25 PMA ground loop generally happens because the stereo is wired up properly to the car battery. I get that, but the earthing system on all my cars are A1 and the player will behave this way in all of them: all of the head units are OEM factory installs and the wiring hasn't been changed at all from stock. No big amps or upgraded speakers.
I have several other players and smart-phones that I run off the same chargers and into the same stereos in the same cars and they all behave perfectly. Only the CLIP+ that acts up in this way.
Quote from: yapper on April 01, 2012, 06:15:15 PMIt would probably be better to use a ground loop isolator on the audio output and leave the player powered properly.Already tried using this:http://www.ebay.co.uk/itm/3-5mm-Earphone-Jack-Ground-Loop-Isolator-Noise-Filter-/280615811526?pt=UK_In_Car_Technology&hash=item41560179c6Still no audio with two grounds.
Assuming the USB you mention here is still the DC adapter you mentioned above, its because your stereo isn't wired right and voltage between the AUX jack and the car's ground that pushes enough current to trigger the overcurrent protection.
Thats not surprising, there would be no ground loop in such a case.
The purpose of overcurrent protection is to keep you from melting your player by plugging into incorrectly wired stereos. Since you launched enough current into the device to trigger the protection, and the player wasn't destroyed in the process, I would say its doing quite a lot of good. Without it you'd might be looking for a new MP3 player and/or car stereo.
They probably present some combination of a higher output impedance and/or AC coupled audio.
An isolator like that will break DC current flowing through a ground loop (well assuming it works as advertised, who knows on ebay), but will not block AC current. I suppose its possible you have some low frequency ripple on the ground, which passes through the transformer. Not sure how that would happen, you'd probably have to get a scope and a good amplifier and take measurements to figure out whats going wrong.
Already tried using this:http://www.ebay.co.uk/itm/3-5mm-Earphone-Jack-Ground-Loop-Isolator-Noise-Filter-/280615811526?pt=UK_In_Car_Technology&hash=item41560179c6Still no audio with two grounds.
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