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Does the Hifiberry DAC work when running RPi with 3.3V

Carsten Hesse

July 28, 2014 11:41

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Hi,

inspired by your HiFiBerry user Fred from France (http://www.hifiberry.com/2014/05/an-audio-streamer-with-digital-output/) I want to use an external linear power supply for optimal audio performance.
Unfortunately, the RPi has an internal voltage regulator for supplying most of its components with 3.3V – but it can be bypassed regarding to Dave Akerman:
http://www.daveakerman.com/?page_id=1294

So my question is: Will the Hifiberry DAC work when the RPi is powered with 3.3V instead of 5V? Has anyone tried this?

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7 comments

• 0
  
  HiFiBerry team July 28, 2014 17:55

  Hi,
  
  it won't work as it is using both the 5V and the 3.3V from the Raspberry Pi.
  
  Best regards
  Daniel
• 0
  
  Carsten Hesse July 29, 2014 11:07

  Thanks Daniel,
  
  is it possible then to power the Hifiberry DAC audio circuit separately?
  
• 0
  
  HiFiBerry team July 29, 2014 12:24

  Not easily as the board is not designed for this. This would need cutting PCB traces.
  
  Best regards
  Daniel
• 0
  
  Carsten Hesse July 29, 2014 12:56

  Understood.
  
  But it is still possible to power the entire HifiBerry DAC board independently from the RPi like described here: http://www.hifiberry.com/forums/topic/separate-power-supply-for-digi-and-dac/
  
  Right?
  
  What I don't understand, though, is that just cutting the 5V pin (P1) connection to the RPi won't completely separate the power supplies as along as there is a 3.3V connection.
  
  What am I getting wrong?
• 0
  
  HiFiBerry team July 29, 2014 14:54

  The DAC board needs 3.3V and 5V, both are provided from the Raspberry Pi. If you cut these you would need 2 external power supplies: 3.3V and 5V. However we won't support this or give any specific instructions how to do this as this is not what the board is designed for. We might think about options for separate power supplies with boards in the future.
  
  Best regards
  Daniel
• 0
  
  Carsten Hesse July 30, 2014 10:47

  Hi Daniel,
  
  I don't wanna bother you. I am just curios and a nerd. Of course I don't expect any support when "messing" with the power supply :-)
  
  Please allow one final question. In the thread that I linked above you said:
  
  

  Dear Robert,
  
  you can remove the Pin 2 on the P5 header soldered to the Raspberry Pi and then power the DAC or Digi from the external 5V input on the board. This is the pin beside the “R2″ print on the Raspberry Pi. While this might give you a slight improvement on the DAC, I do not expect any changes on the Digi. We even tested it on the DAC and could not find measurable differences as the voltage regulator on the boards works very well. However, you can try it by yourself.
  
  Best regards
  Daniel

  
  
  Just to get things right: If this quote is true, then the Hifiberry DAC wouldn't need an additional 3.3V supply from the RPi. But since you stated above it DOES need 3.3V AND 5V from the Pi I guess the quote is wrong (or misunderstood) and there is no way to power the Hifiberry from the external 5V input on the board only.
  
  This means Robert did not achieve to "really" separate the power supplies as he stated in his thread. Yes or no?
  
  Thanks for your patience!
  
  P.S.: I love my Hifiberries :-)
• 0
  
  HiFiBerry team July 30, 2014 12:02

  In this case the 3.3V will still be provided by the RPi, but only the 5V come from the external PSU.
  
  Best regards
  Daniel