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I'm using the speaker bonnet / following instructions from adafruit: https://learn.adafruit.com/adafruit-speaker-bonnet-for-raspberry-pi/raspberry-pi-usage.

I followed all of the steps (skipping the sound tests because on a previous install I hurt my ears!) and after both reboots alsamixer still doesn't have volume controls.

If I look in aplay I can see the device:

$ aplay --list-devices
**** List of PLAYBACK Hardware Devices ****
card 0: sndrpihifiberry [snd_rpi_hifiberry_dac], device 0: HifiBerry DAC HiFi pcm5102a-hifi-0 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0

But amixer is totally unresponsive (amixer -h gives the commands but amixer and amixer scontrols and amixer -c 0 and so on all give no output whatsover!

All of the tutorials I can find from 2 hours of searching seem to assume that if you can see a device in aplay you should be able to see it in amixer.

What could be wrong? Is it because I'm using Raspbian stretch? Adafruit seems to imply they don't support it: https://forums.adafruit.com/viewtopic.php?f=19&t=122904

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amixer does not show any mixer controls because your hardware does not have any mixer controls.

The system uses the softvol plugin too insert a software-emulated mixer control into the playback stream, if needed, but this plugin is run only when the PCM device is actually used, so it cannot create the virtual mixer control before the first run.

To avoid playing a test sound at 100 % volume, play an empty or silent file.

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    Since this is a problem that would only confuse someone avoiding the test sound and someone unfamiliar with playback streams, could you give an example of what a "silent file" is? When you say "empty file" do you mean literally touch tmp && aplay tmp?
    – KCE
    Dec 18 '18 at 9:08
  • Yes, that aplay tmp would work. You could create a silent file by recording silence, or by editing some existing file and reducing its volume to 0%.
    – CL.
    Dec 18 '18 at 11:09
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Wow, so it turns out that (and I still don't know why) you have to play a test sound at 100% volume before you can use any tool which would otherwise control that volume (such as alsamixer or amixer).

That's the only answer I have right now. I really hope I'm wrong (i.e. there is some way to turn down the volume before playing sound) but this is what fixed my problem.

I've seen other threads where people say it started "mysteriously" working and it's possible that they for some reason actually got a sound through the device.

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