Car PSU or PC Based? Hum!

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Deafuser

Member
Joined 2012
Hello all.

I didn't know where to ask this, but I have an annoying hum issue! I've got an early Pi installed in my van. I bought a Shenzen 5 volt switcher

https://www.amazon.co.uk/gp/product/B00HV4EPG8/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1
It supplies my pi and Muse USB dac

https://www.amazon.co.uk/SMO-Conver...&sr=1-2-catcorr&keywords=MUSE+USB+DAC+PCM2704

Well, I got this annoying hum. I've unplugged the rca composite video to lcd display, does nothing, unplugged the lcd display power, does nothing. Got a Lowpass filter on the main 12 volt line and elliminated the alternator whine I had, got de-coupling caps on the audio rca lead. The system is silent until I boot the PI, you can hear the text load, the desktop display, you can hear VLC player being launched. Seems like the noise is beeing fed from the PI through the USB dac!

So, I think I've dealt with the usual Ground Loops and alty whine, what else can I do?

Thanks, Mike
 
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Deafuser

Member
Joined 2012
Hi, sorry for late reply. The pi headphone output creates more noise. I installed X screensaver and you can hear all the graphics changing as the screensaver changes patterns. The amp is an LE SON 2 channel cheapy from eBay. It's quiet when I unplug it's audio input.
Thank you
 
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