Question Strange power issue causing audio blips?

Hi all,

I have just introduced a Raspberry Pi running Volumio into my system with a HifiBerry Digi+ Pro running SPDIF into a Cambridge Audio DACMagic Plus. The Pi is powered by a standard Raspberry Pi USB power supply that is plugged into a Tacima 6 way mains conditioner extension lead (with the rest of the hifi components).

I have noticed, that when plugging my laptop power supply in elsewhere to another outlet in the room, there is a minor 'blip/dropout' in audio playback, even though the Pi is playing from a locally attached USB drive.

I also get the blips/dropouts on the unrelated Raspberry Pi playback when the metal of the USB plug on my external CD drive touches the metal of the USB socket on my laptop.

What could be causing this? I have a socket tester and multi meter so is there anything I can go looking for?
 

larkone

Member
I would look towards a noisy or failing laptop power supply. I had an LED bulb that had dodgy/noisy power supply and it would take out my broadband every time it switched on.
 
I would look towards a noisy or failing laptop power supply. I had an LED bulb that had dodgy/noisy power supply and it would take out my broadband every time it switched on.
I’ll check this out but I’m pretty sure it happens with other DC powered devices.
 

noiseboy72

Distinguished Member
It sounds like at least one component has the mains earth connected to the signal ground and the noise it produces upsets this enough to trip up the digital signal for a few seconds.

You may find that if you measure between the USB sockets and the mains earth you get a few volts - which is enough to cause the issues. Fix might be linear 5V supply - which will have a transformer to isolate it from the mains.
 

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