Amixer does not work

[Satoshi]

Hi,
I want to change the output volume using amixer but it seems amixer doesn't work.
I entered the following commands on terminal but volume didn't change.

amixer set 'Master' 100%
amixer set 'Master' 50%
amixer set 'Msster' 0%

Reply looks OK but the volume is always same.
=====================================================
Simple mixer control 'Master',0
Capabilities: pvolume
Playback channels: Front Left - Front Right
Limits: Playback 0 - 127
Mono:
Front Left: Playback 127 [100%] [6.00dB]
Front Right: Playback 127 [100%] [6.00dB]
=====================================================

I also configure some parameters using alsamixer but sound didn't change too.
I really want to controll the output volume in software.
Am I missing something?

[my environment]
Board : Raspberry Pi 3
OS version : Raspbian GNU/Linux 8 \n \l
driver : audio.injector.scripts_0.1-1_all.deb.tar.gz

[flatmax]

Hi there,

I have investigated this "feature" you mention and it turns out that the Wolfson Micro chip which is used in this device doesn't have a hardware control for the RCA volume. It does have this control for the headphone jack, so if you want you can switch to using the headphone jack instead of the RCA connectors. If you are happy to use the potentiometer to control the RCA output jack volume, then that is great, otherwise, read on for a nice solution.

If you want to use the RCA connectors, then the following post explains how to implement an ALSA softvol control which will allow you to control the RCA connectors from the commandline and alsamixer :
viewtopic.php?f=5&t=572

Hope that solves your approach to volume control of the RCA connectors from the command line.
thanks
Matt