Hello, I have an Pi 3+ with Raspbian OS and the DAC+ Pro. The output is too low with sinusodial sine wave e.g. 50/100/200Hz. At the scope measured at the XLR out I get 600mV.
Alsamixer is at 100%
Any suggestion how to get more volume out of the XLR.? Should be at max level arround 4Vrms, right.?
Thank you.!
What exactly is "at 100%"? Raspberry Pi OS uses PulseAudio. My guess is that you only changed the PulseAudio volume. Check the output of
amixer
I have now photos of the alsamixer, audacity 200Hz wav and the scope output level at the XLR connector.
That doesn't really help.
First: Don't use audacity. There are too many settings that may be wrong. A simple tool is sox:
apt-get install sox
play - n synth sine 1000
Second: Post the output of the command
amixer
Third: How do you connect the oscilloscope? From GND to each signal, the output should be around 3Vpeak
Thank you for your support.
amixer output:
pi@raspberrypi:~ $ amixer
Simple mixer control 'Master',0
Capabilities: pvolume pswitch pswitch-joined
Playback channels: Front Left - Front Right
Limits: Playback 0 - 65536
Mono:
Front Left: Playback 65536 [100%] [on]
Front Right: Playback 65536 [100%] [on]
Simple mixer control 'Capture',0
Capabilities: cvolume cswitch cswitch-joined
Capture channels: Front Left - Front Right
Limits: Capture 0 - 65536
Front Left: Capture 65536 [100%] [on]
Front Right: Capture 65536 [100%] [on]
pi@raspberrypi:~ $
The sox generator is running. I did play again 100Hz. Measurement is now done at PIN 2 and 3 from XLR. Looks like I have more volume, but the sine wave has some clipping, see photo from scope.
The mixer output is not the mixer of the DAC+, but probably from PulseAudio. Check the amixer manual page on the command line option to get the mixer controls from the DAC+ or disable/stop PulseAudio.
BTW: The simplest way to have a "clean" installation with correct mixer settings is using HiFiBerryOS (https://www.hifiberry.com/os). Even if you don't use it later, it probably simplifies debugging.