Filter Noise from amp for USB port

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I built a portable speaker using a DTA-2 Dayton amp. It ispowered by a 12V 9AH SLA battery put inside.
I also run in parallel to the amp a 12V cigarette lighter jack and two 5V USB (1A and 2.1A). I had put in the usb ports to charge a phone or power a bluetooth dongle to make my speaker wireless. Although charging phones and tablets works great when I plug in a bluetooth receiver theres noise coming from the amp that passes into the usb and into the bluetooth receiver and then by the aux cord to the amp.

When the amp is off and i use the usb ports as a power supply for the bluetooth there is no noise. when bluetooth is powered by 110v wall adapter there is no noise. I thought of buying a high end bluetoot hreceiver that might have a noise filter in it but i guess its easier to make a noise filter but not quite sure how to go by it to solve my problem 100%

Any input would be greatly appreciated thanks!
 
The speaker works wonderfully if you plug in the aux cord or through the rca jacks. The only problem happens when you plug in the bluetooth either in the usb ports or the 12v cig lighter (they both do the same noise thing as shown in the video) AND the DTA2 amp is working.
If the amp is not on then there is no noise in the bluetooth dongle.
Thats why i think theres feedback from the amp since theyre just all connected in parallel.

I need some sort of filter between the amp and usb power source?
 
This kinda suggests a Bluetooth transmit or receive problem. If you don't have an oscilloscope to take a look at the supply rails or a 5V capable linear supply an option to rule the USB supply in or out would be to stack up a few batteries to get 5V. You'd need a multimeter to check the voltage and knowledge of USB pinouts and such.

Another option would be a non-Bluetooth USB powered audio source. All the ones I know of offhand which accept SPDIF expect a host to connect to, though.
 
But i dont think the bluetooth is the problem here. When the amp is off the output is very clean through the usb. If i power the bluetooth with the usb port and listen to it through headphones or any other speaker for example there is no noise when the amp is OFF. there is also no noise through the bluetooth dongles when i power them with any other 5v source.

I just need to have a filter that filters out the ac noise going into the usb when the amp is on and this is what my question is.
How do i make a filter for this?
 
You're saying this is an issue with ground bounce between the amp input and USB ground picked up by the Bluetooth modules but not the aux ground? If so I'd suggest the article on grounding under the Articles menu up top as a starting point. Among other things that should help with expanding the schematic of post 3 to indicate the ground topology more specifically.
 
Thanks alot for your replies.

This is the circuit drawn differently. I read through parts of that article. However, since I have a battery as power source, I cant really ground stuff elsewhere...
As you can see the amp and usb are plugged right onto the battery. I feel that the amp is blurring the 12v to the usb.



An externally hosted image should be here but it was not working when we last tested it.
 
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