Audio noice filter, can't get rid of it

Seems likely to me it's your charger putting out high frequency noise. Get another charger and try it.

 

Some questions to clarify the situation:
(1) do you have two cables plugged in, one for power (to the 12V socket) and one for audio (to the AUX jack)?
(2) if so, then does the audio clean up (noise go away) when you unplug the power cable and run on battery only?

If yes to both, then you are suffering from a 'ground loop'. Several other threads have discussed this, but I don't recall if any of the parties came back confirming particular solutions.

 

I did buy a ground loop isolator from ebay and it helped a lot.

 

Or try it for a minute without the charger altogether.
That should rule the charger in or out real quick.

 

Like 69shovlhed said, you are having a problem with a ground loop (it's not the charger). What is happening is that the Galaxy audio ground is different from it's power ground. When you connect those grounds together noise (from the car's inverter) travels between these two grounds, coupling the noise into the audio. The solution is a Ground Loop isolator, such as this one from Amazon or this one from Radio Shack (that is the one that I have in my 2007) - if you can find a store these days.


















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In my experience I noticed the noise going away if you unplug the power on the device, no noise if just using the battery of the device, clearly a ground loop problem. Here’s something I did to have a dedicated music player in the car (not ideal for a phone you carry around) I bought an old Samsung galaxy s3 just for this purpose. First a rerouted the headphone plug by plugging a cable in the center console and running it to the glove compartment. For power I tapped into the cigarette plug under the dash, I ran this wire to a NO side of a relay. Then I found a constant 12v wire under the steering wheel and wired it to the NC side of the same relay. Then to activate the relay I used the switched 12v at the cigarette plug I was already using. The output of the relay was wired to a cigarette plug that I placed in the glove box. So to sum it up I had a place to plug power and an audio input in the glove box, except the power was switched in a special way. When the car was running the power was disconnected from the music player (the old s3) this allowed it to play with just the battery and no noise interference. Then when the car was off the constant 12v would connect to the player and charge the battery. So it was always ready to play with a fully charged battery when the car was started and no ground loop noise. I have since traded the car (regrettably so) and I wonder how confused the new owners must be if they try using the charge wire in the glove box...

 

Three things will help:
1. Ground loop isolator
2. Different Phone Charger
3. Tying the grounds between your phone and the Prius' audio system more strongly together.

How I did number 3 when I installed my aftermarket headunit is I connected the ground wire of the CD player both to the factory ground wire, but also ran a 12 AWG. wire to a nearby chassis bolt. If you wanted to do this on the factory headunit, you'd obviously need to take apart the dash, but it could be worth it. Basically, the less electrical "distance" between the phone charger and the headunit, the less noise will be induced.

 

i got this : VODOOL Ground Loop Noise Isolator Audio Anti jamming Device Noise Isolator with 3.5mm Audio Interface for Home Stereo L3FE-in Wireless Adapter from Consumer Electronics on Aliexpress.com | Alibaba Group