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RPi B+ // DAC+ // Volume hardware control

Kevin Deplae

January 15, 2016 15:49

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Hi,

I just received my DAC+ and installed it on a new RPi B+ that has been running Volumio for a week (from the RPi's jack).

Everything seems to work after:

• Enabling the I2S driver (set to Hifiberry +)
• Audio output to  sndrpihifiberry
• Mixer type to software

As soon as I try to switch to Audio Output = ALSA / Mixer Type = Hardware, the music stops (as I guess the RCA isn't even used then ?). As this is a newly installed volumio and a new DAC+ (not the light) this should work if I understand correctly.

The /etc/mpd.conf has the config below in it:

audio_output {

type "alsa"
name "Output"
device "hw:1,0"
mixer_control "Playback Digital"
mixer_device "hw:1"
mixer_index "0"
dop "no"

}

Also check the following link, without luck currently

http://support.hifiberry.com/hc/en-us/articles/205385241-Mixer-controls-on-the-HiFiBerry-boards

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14 comments

• 1
  
  HiFiBerry team January 17, 2016 19:27

  Hi Peter,

  if you have an normal volume control on your headphone amplifier, I would always recommend this. This usually provide the best signal-to-noise ratio.

  Best regards
  Daniel

• 0
  
  Kevin Deplae January 15, 2016 15:57

  I just found the following topic and the last post could (and probably is) the same thing as I have.
  My RPi is bought in the last week of 2015 and installed in that same week with all the updates.

  Is their any solution and what Volumio version/image do I need to use ?

  http://support.hifiberry.com/hc/en-us/community/posts/201845951-HifiBerry-DAC-Alsa-PCM-control-not-available

• 0
  
  HiFiBerry team January 15, 2016 16:13

  Hi Kevin,

  I don't know which Linux version your system is using. The name of the volume control has changed a few times. Check the output of the command "amixer". It will show you the available mixer controls and their names.

  Best regards
  Daniel

• 0
  
  Kevin Deplae January 15, 2016 17:38

  Hi,

   

  I'm running the last version of the volumio image (downloaded from volumio). I'll post the amixer output when I'm back home.

• 0
  
  Kevin Deplae January 15, 2016 17:42

  -- double post --

  Edited by Kevin Deplae January 15, 2016 21:19
• 0
  
  Kevin Deplae January 15, 2016 21:24

  pi@AUDIOLIVING:~$ uname -a
  Linux AUDIOLIVING 3.18.5+ #748 PREEMPT Wed Feb 4 21:24:41 GMT 2015 armv6l GNU/Linux

  ------------------------------------------------------------------------------------------------------------

  Simple mixer control 'PCM',0
  Capabilities: volume
  Playback channels: Front Left - Front Right
  Capture channels: Front Left - Front Right
  Limits: 0 - 215
  Front Left: 207 [96%]
  Front Right: 207 [96%]
  Simple mixer control 'DSP Program',0
  Capabilities: enum
  Items: 'FIR interpolation with de-emphasis' 'Low latency IIR with de-emphassis' 'Ringing-less low latency FIR'
  Item0: 'FIR interpolation with de-emphasis'
  Simple mixer control 'Playback',0
  Capabilities: volume
  Playback channels: Front Left - Front Right
  Capture channels: Front Left - Front Right
  Limits: 0 - 1
  Front Left: 0 [0%] [-6.00dB]
  Front Right: 0 [0%] [-6.00dB]
  Simple mixer control 'Playback Boost',0
  Capabilities: volume
  Playback channels: Front Left - Front Right
  Capture channels: Front Left - Front Right
  Limits: 0 - 1
  Front Left: 0 [0%] [0.00dB]
  Front Right: 0 [0%] [0.00dB]
  Simple mixer control 'Auto Mute',0
  Capabilities: pswitch
  Playback channels: Front Left - Front Right
  Mono:
  Front Left: Playback [on]
  Front Right: Playback [on]
  Simple mixer control 'Auto Mute Mono',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [on]
  Simple mixer control 'Auto Mute Time Left',0
  Capabilities: enum
  Items: '21ms' '106ms' '213ms' '533ms' '1.07s' '2.13s' '5.33s' '10.66s'
  Item0: '21ms'
  Simple mixer control 'Auto Mute Time Right',0
  Capabilities: enum
  Items: '21ms' '106ms' '213ms' '533ms' '1.07s' '2.13s' '5.33s' '10.66s'
  Item0: '21ms'
  Simple mixer control 'Clock Missing Period',0
  Capabilities: enum
  Items: '1s' '2s' '3s' '4s' '5s' '6s' '7s' '8s'
  Item0: '1s'
  Simple mixer control 'Deemphasis',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [on]
  Simple mixer control 'Digital',0
  Capabilities: pswitch
  Playback channels: Front Left - Front Right
  Mono:
  Front Left: Playback [on]
  Front Right: Playback [on]
  Simple mixer control 'Volume Ramp Down Emergency Rate',0
  Capabilities: enum
  Items: '1 sample/update' '2 samples/update' '4 samples/update' 'Immediate'
  Item0: '1 sample/update'
  Simple mixer control 'Volume Ramp Down Emergency Step',0
  Capabilities: enum
  Items: '4dB/step' '2dB/step' '1dB/step' '0.5dB/step'
  Item0: '4dB/step'
  Simple mixer control 'Volume Ramp Down Rate',0
  Capabilities: enum
  Items: '1 sample/update' '2 samples/update' '4 samples/update' 'Immediate'
  Item0: '1 sample/update'
  Simple mixer control 'Volume Ramp Down Step',0
  Capabilities: enum
  Items: '4dB/step' '2dB/step' '1dB/step' '0.5dB/step'
  Item0: '1dB/step'
  Simple mixer control 'Volume Ramp Up Rate',0
  Capabilities: enum
  Items: '1 sample/update' '2 samples/update' '4 samples/update' 'Immediate'
  Item0: '1 sample/update'
  Simple mixer control 'Volume Ramp Up Step',0
  Capabilities: enum
  Items: '4dB/step' '2dB/step' '1dB/step' '0.5dB/step'
  Item0: '1dB/step'

  --------------------------------------------------------------------------------------------------------------------

  Selected the Hifiberry + for the DAC+

   

   

  

   

  Selecting Hardware under 'Mixer Type' breaks all audio playback

  

   

• 0
  
  Peter January 16, 2016 03:42

  @Kevin: FYI, and in case you have not noticed yet, the "Digital" control parameter works differently in amixer and alsamixer.  (right now, not necessarily always was it so).

  100% in amixer corresponds to 100 in alsamixer which corresponds to +24db (VERY loud), BUT, smaller numbers longer correspond to the same db settings.  In amixer 81%~~0db, a safe level.  BUT in alsamixer 81 is still ~~+18db (!), and only down at 40 you get 0db.

  This goes part way to explaining the thread you reference above, not sure it addresses your problem.  However, if your app uses volume calculations based on the alsamixer scale, then the volume might be way too low.

   

• 0
  
  HiFiBerry team January 16, 2016 07:09

  The mixer control name is "PCM":

  Simple mixer control 'PCM',0
  Capabilities: volume
  Playback channels: Front Left - Front Right
  Capture channels: Front Left - Front Right
  Limits: 0 - 215
  Front Left: 207 [96%]
  Front Right: 207 [96%]

  Best regards
  Daniel

• 0
  
  Peter January 16, 2016 21:43

  After reading Daniel's post I downloaded the latest version of Volumio.  (Raspberry Pi 2 B, HiFiBerry DAC+, Linux volumio 3.18.5-v7+, Volumio Version 1.55)
  
  The installation went well, software volume control worked but hardware volume control did not.

  To get hardware volume control to work, I had to edit the mixer_control name in /etc/mpd.conf, but only as a last step AFTER I configured everything else, and after I selected "Hardware" in MENU->Playback->Mixer type.
  
  Not sure if this is a known bug, or if I just made a common installation mistake, but there are other posts with similar problems on the Volumio forum and elsewhere.
  
  In /etc/mpd.conf I changed mixer_control to "PCM" to match the above post, and correspond to alsamixer and amixer commands (those worked from the start after installation).
  
  The tail of my mpd.conf now looks like this:
  
  audio_output {
  
                   type           "alsa"
                   name           "Output"
                   device         "hw:0,0"
                   mixer_control  "PCM"
                   mixer_device   "hw:0"
                   mixer_index    "0"
                   dop    "no"
  }
  
  Now when I run alsamixer from the command line, the PCM slider follows the volume control knob in Volumio Playback screen.
  
  Unfortunately, mpd.conf reverts the next time you save it in the Volumio Playback Menu, so the control name must need to be changed someplace else (?)
  
  

  Edited by Peter January 17, 2016 00:26
• 0
  
  HiFiBerry team January 17, 2016 08:41

  Hi Peter,

  looks like a Volumio bug to me. I recommend contacting the developers. 
  
  Best regards
  Daniel

• 0
  
  Peter January 17, 2016 19:23

  Hi Daniel,

  I will make a post in one of the Volumio forums, but frankly I know very little about Volumio or Rune Audio. I have tried using both, so far with mixed results.  If I understand correctly, the Volumio team is working on a complete rewrite of the software using a new development tool, to be released as Volumio 2.0, and they are no longer making fixes to 1.55. From what I read, it is going slowly.  I can only wish them well, and look forward to 2.0.

  I made the above post for the OP, or you, or someone who knows more about Volumio than I do.  

  If this is a Volumio bug, it has plenty of company, and probably above my paygrade.  I came across a couple others, somewhat documented in the Volumio forum, with suggested fixes requiring editing the java script code.  I barely managed one patch, but only because the explanation was in plain english.  There are over a dozen (!) JavaScript repositories on github.  

  Right now, the Volumio 1.55 volume control is awkward in casual use (to say the least).  This applies to software or (when you can get it to work) in hardware.

  At the moment, for testing I use the amixer commands you kindly explained in another post.  For casual listening I leave volume control disabled, and I use the analog volume control knob on my headphone amp, or on the receiver that the output of DAC+ is connected to.  Basically I am just enjoying the music and staying away from the command line while waiting for a second set of boards b/f doing any more testing... :D

  Regards,

  Peter

  Edited by Peter January 17, 2016 19:26
• 0
  
  Peter January 17, 2016 21:21

  Daniel,

  I am using a NuForce Icon HDP, about 5 years old.  At the time it was the best I could find that fit my budget. It is not the equivalent of a  full-size component DAC but similar features.

  It has decent sound for my use, and convenient for testing b/c it has one of each, analog RCA line in, digital/optical, digital/coax, and of course USB, with a selector switch on the front.  Line out on the back, and 1/4" headphone out on the front.

  I hope to use this for testing when I get the second set of boards, sometime next week.

  Peter

  Edited by Peter January 17, 2016 21:23
• 0
  
  Kevin Deplae January 20, 2016 15:57

  Hi,

  To be complete, I wanted to let you know that this is a bug in Volumio.

  I switched to moOde audio (fork from Rune and Volumio) and hardware volume control
  was working immediatly.

• 0
  
  Peter January 20, 2016 16:48

  Hi Kevin,

  Thanks, I will try Moode.

  It may take me a couple days to get around to it. 

  I found a patch to enable hw volume control for RuneAudio, so good chance it can be patched in Volumio as well. 

  Rune and Volumio are using Alsa the same way, I think, and they are using the wrong mixer_control string.  There is a very long thread on the Rune Audio Forum about that.  I understand the patch, but not everything in that thread is clear to me.

  Really unfortunate, I wonder how many people just give it a quick try, and then give up for lack of time or knowledge.

  I have found that even with volume control disabled in the RuneAudio UI, I can still set the nominal level using amixer commands.  This prevents the possibility of clipping and distortion in the dac.  I use this to set what I think is the correct nominal output level at the Dac+

  amixer set PCM 207 (this avoids the issue of mapping % to an absolute number)

  After that, I use the volume control knob on my headphone amp or on the receiver, depending on which one is in use.

  Regardless of the bug in hw volume control, I am happy with the sound from the DAC+, and honestly, I am thrilled I was able to get this working at all (no Alsa gurus or Linux wizards in this household, LOL).

  Peter