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I have a Raspberry Pi 2 running Open Source Media Center (aka OSMC), and when it runs, I hear a very high frequency hissing noise coming from the Pi.

In my family, I am the only one able to hear this (as well as the one able to hear some noise from the dimmer of my desk lamp), but it's extremely annoying, mostly because the Pi is located in my room and this forces me to turn it off when I go to sleep.

Another thing I have noticed is that a Raspberry Pi 3, which I have also been using lately, does not produce that awful sound. Is this normal? What can I do about this? Or is my Pi just broken?

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Unfortunately this is normal.

The original Raspberry Pi Model A and B used a linear voltage regulator to step down from 5V to all the lower voltages it requires for its operation.
Its advantage is that it has a pretty smooth and steady output voltage. But the down side is that the excess voltage is literally being burned. (e.g. a 3.3V linear voltage regulator provided with 5V will have to dissipate the 1.7V as heat. With a higher input voltage more heat has to be dissipated.) This makes those inefficient.

In the Raspberry Pi Model B+ and A+ and in Raspberry Pi 2 Model B they switched to more efficient switching power regulators. Those are more efficient but the switching of the current introduces ripples in the output voltage that are audible.

In Raspberry Pi 3 Model B, A+ and B+ they moved to a custom chip named MXL7740 that has a combination of switching and linear regulators to combat that issue.

More to find on the official blog entry about the custom chip.

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    Thanks for this complete and detailed answer. Three years late, but an interesting read for sure :p – Manchineel Oct 22 at 8:58
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It may just be you (your family cant hear it) or it might not, either way try a USB sound card it's pretty cheap.

also just saying this seems like a duplicate from: 3.5 mm jack starts to "hiss" after sound is played

however there weren't any real good answers except for the USB sound card

  • Why is this a downrated answer? The USB audio dongles take care of the hissing perfectly. – user2497 Oct 22 at 15:03

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