Hello, first of all, I’m thankful that I finally found a soundcard which does what I need.
Though there is one problem currently:
I’m building a musical instrument running puredata on raspberry pi to process audio in real-time. So basically the audio from a pickup comes in through the microphone jack, gets processed in puredata and is played at the same time through the headphone and speakers. The first minute everything is fine, but then after that the sound on one side of the headphone and speaker gets killed and after about 30 sec it stops completely making any sound. After restarting the signal processor of pure data it works fine but again only for about one minute. I don’t have this problem when I use a usb soundcard, so it shouldn’t depend on the software.
I’m thinking maybe it’s a problem of performance. Is the soundcard suitable for real-time processing at all? And maybe if I deactivate the speaker which I don’t need anyway, it would get better, what do you think? (and how could I deactivate it?)
The other thing is that the chip on raspberry pi gets really hot usually because of the processing. And since the soundcard is directly on top of it, maybe the heat causes this problem? but that would not make sense because after restarting the software it works again immediately.
[UPDATE]: I actually found out that the problem isn’t with the speakers or headphone jack. It’s the external microphone jack that stops working after a short time. I found this out accidentally when some recorded loop was still playing but no sound was getting in through the mic jack.
If I had to guess I think this could be coming from something changing the alsa setting (puredata?) after one minute, to investigate an idea of what you could try:
When the sound is working as you want, in a terminal save your Alasa configuration:
sudo alsactl --file working_configuration store
When this is not working anymore save it again on a different file:
sudo alsactl --file not_working_configuration store
Then try to restore the working configuration:
sudo alsactl --file working_configuration restore
is it working again?
With a text editor try to see if you have any difference between working_configuration and not_working_configuration
I can confirm this issue, tested on two different boards with different Ultra++ units and various stereo electred microphones. The problem starts as soon as I mute the internal mics. Audio works for a minute or so, then both channels are dying. It is not a problem of configuration changes. I was able to partly solve the issue by leaving the internal mics on, but turning down the left and right boost mixer gain for input1 to 0dB, the lowest possible level for the internal microphones. Here’s how to reproduce:
Plug a electred stereo microphone into external jack.
Load the preset_external_jack_microphone_input2 using alsactl.
Since this is a mono preset and I needed stereo input, open alsamixer and change ADC Data Output Select to Left ADC Data = Left ADC, Right ADC Data = Right ADC.
Start a recording. Depending on the microphone, wait one or two minutes until the right or left channel should drop out.
Hope this helps to find the issue. I’m using the Ultra++ for a live streaming project (darkice + icecast), broadcasting live microphone input from outside my house.
Thanks sbar for your effort. Unfortunately both presets don’t solve my problem, the external mics are still dying after working one or two minutes. It seems to me that there might be an inaudible noise which gets louder and louder in the background until the inputs are dying because of overdrive. Some noise is still coming through the mics after they have died, but only very distorted. I can provide an audio example if this could help to solve the issue.
Here, everything seems ok.
The sound is stable, clear, not noisy at all…
It 's not easy !
It might be worth experimenting with another microphone.
Could you do it?
Thanks.