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rpi2 and DAC+ distortion

steven lievens

February 27, 2015 13:32

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Hi,

I recently purchased a RPI 2 and a DAC+ to use with openelec 5.04 (fresh install).

Setting up the dac+ was very simple (following the instructions on the site for dtoverlay), but after listening a couple of songs I noticed high tones are distorted. There comes a sort of cracle in the sound.
For example ALT-J's Intro of their first album ; the first piano tones are already distorted.

What I've tested yet:
- installed Volumio instead of Openelec, same problem.
- tested with headphones directly connected to the dac, same problem.
- same rpi, power supply buth other dac (Sabre), same problem

So I think I can exclude the following as possible cause:
- cables
- amp/speakers/headphones
- rpi
- software
- power supply

Anyone had similar experienc with the DAC+?

Regs,

Steven

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7 comments

• 0
  
  Chris Mullen February 27, 2015 13:51

  Make sure u test sound from the DAC+ by logging onto the RPI directly and playing sound, ie not thru a casting DLNA or airplay client.
  
  I have not had any distortion issues from my DAC+, unless I do nonsense like cast from two clients at the same time.
  
  I believe the DAC+ module does a system hw test during module install, but Daniel can confirm that.
• 0
  
  HiFiBerry team February 27, 2015 14:18

  Hi Steven,
  
  we have heard similar feedback from other users. OpenElec seems to increase the volume of the output. You should do the following:
  
  1. Set the master volume of the DAC to 96%
  amixer sset PCM 96%
  2. Reduce the volume in OpenElec itself.
  
  For music playback only, I would recommend a pure audio distribution like RuneAudio, Volumio or PiMusicBox.
  
  Best regards
  Daniel
• 0
  
  steven lievens February 27, 2015 14:41

  Hi Daniel,
  
  thank you for the feedback ; I'll test it later this day.
  
  

  For music playback only, I would recommend a pure audio distribution like RuneAudio, Volumio or PiMusicBox.

  
  Do you mean that the problem does not exist on those distributions? Because I've tested with Volumio and had the same problem...
  
  Thanks,
  
  Steven
• 0
  
  HiFiBerry team February 27, 2015 16:52

  Just make sure, the mixer is set to not more than 96%. As every distribution is a bit different, I can't say which one is using what default mixer volume settings. Sometimes these things even from release to release. One thing you can do is to put the "amixer sset PCM 96%" (or even lower) into an autostart file.
  On OpenElec, this is /storage/.config/autostart.sh:
  http://wiki.openelec.tv/index.php/Autostart.sh
  
  Best regards
  Daniel
• 0
  
  steven lievens March 01, 2015 06:48

  Problem is solved with adjusting the mixer to 96% ; I'm a happy person now ;)
  Now I can fully enjoy the clarity of the highs this dac produces.
  
  Thanks again,
  Steven
  
  
  
  
• 0
  
  HiFiBerry team March 01, 2015 08:10

  Thanks for letting us know.
  
  Enjoy your sound!
  Daniel
• 0
  
  Chris Mullen March 17, 2015 11:17

  Steven,
  
  Wondered if lowering the mixer <96% also solved the problem for Volumio distribution with a RPI2 and DAC+?
  
  Did the distortion go away? What release version of Volumio did you use?
  
  I was looking for the best distribution to setup a RPI2 and AMP+ board. Wanted to use Volumio but saw posting on other forums that Volumio crashes on the RPI2. Wondered what you have found.
  
  chris