Tie Teensy AGND to Audio Amplifier AGND?

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jeraymond

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Hello,

I'm using a Teensy 3.2 and Audio Adaptor Board with the Adafruit MAX9744 Audio Amplifier. When I power the audio amplifier with a 12V adapter, the Teensy with a USB adapter and connect the two via an audio jack cable all is well and the sound is clear.

I'm looking to power both devices from a single power source. The amplifier board has 12V VDD out so I wired a 5V linear voltage regulator to VDD and GND (with necessary capacitors) to power the Teensy. This works fine for power but now I'm getting some audio feedback when playing sound. I suspect this is a ground loop causing the audio interference.

Both the Teensy and the audio amplifier have AGND. Would connecting these help reduce the noise or have any negative effects on the system? Would using a Audio Ground Loop Noise Isolator fix the issue and be a better solution?

Thanks,

Jeremy
 
The Audio Ground Loop Noise Isolator I ordered arrived and has eliminated the audio feedback hum.

I still wonder if there is a different way to eliminate the feedback by fixing the grounding and not require another part. AGND is the ground reference for the amplifier and the Teensy. Does wiring them together make sense? Would this give them the same reference ground and eliminate feedback?
 
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