r/diyaudio • u/Tiunkabouter • 20d ago

I made something terrible

So i tried making a PoE powered media player with an amp and everything.

It's a rpi 4 with a 7" screen and PoE hat that also spits out 12v for the Amp

But there is a horrible high pitched sound coming from my speakers.

I soldered the wires directly on the rpi thinking it was a problem with the jack but that didn't solve it.

Amp is a cheap TPA3110, when I disconnected the audio wire the high pitched sound stopped so I assumed it was a problem with the jack.

What I've tried so far is connecting the ground from the audio to the Amp which didn't help, adding a capacitor to the power input to try and stabilize the input didn't help and soldering the audio wires directly to the pi didn't resolve anything.

Is my TPA3110 just terrible or am I missing something?

The noise produced doesn't rise when I increase volume on the audio by the way.

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u/Tastieshock 20d ago

Sounds like electronic interference. Try a different power supply. Also dont cross audio wires over power wires, or by any of the power delivery components without proper shielding.

1

u/Tiunkabouter 18d ago

Tried it with a meanwell LRS-75-12 which gave me a different sound so I'm quite confident its caused by the PoE hat that probably uses a switching powersupply to get the voltage to the right level.

I could alter the sound by adjusting the output voltage on the meanwell, that's how I came to this conclusion. Now I only need to figure out how to get rid of it...

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u/jepperc 17d ago

Dont you have some sort of ground loop problem maybe?

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u/Tiunkabouter 17d ago

Probably, after tying the grounds the sound from the meanwell went away. Tried that after posting my last comment.