# Possible alsa error? **URL:** \ **Category:** GNU Radio\ **Created:** [July 17, 2014, 4:43pm UTC](https://www.ruby-forum.com/t/possible-alsa-error/231021 "2014-07-17T16:43:10Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\ **Post date:** [July 17, 2014, 4:43pm UTC](https://www.ruby-forum.com/t/possible-alsa-error/231021/1 "2014-07-17T16:43:10Z")
Hello, sorry that the first message was sent before I could finish explaining. my fault, please excuse. I am using an 8 channel USB sound card as an audio source and the first test I do is to ensure that the audio signals can be seen in the attached QT scope block screen shot. This works perfectly when the PC is first started, however when I stop the flow graph and then start it again I get an alsa error message. When the flow graph is _working correctly_ I get the following message: \<\<\< Welcome to GNU Radio Companion 3.7.5git-0-g2bb2b314 \>\>\> Preferences file: /home/drdc/.grc Block paths: /home/drdc/target/share/gnuradio/grc/blocks /home/drdc/.grc\_gnuradio Loading: “/home/drdc/Documents/8 ip switch test.grc” > > > Done Showing: “/home/drdc/Documents/8 ip switch test.grc” Generating: “/home/drdc/Documents/InputSwitchTest.py” Executing: “/home/drdc/Documents/InputSwitchTest.py” Using Volk machine: avx\_32\_mmx > > > Done After the flowgraph is restarted I get the error message that can be seen in the attached screen shot. running sudo alsa force-reload does not fix the problem. Only a reboot will fix it. Some background: To get the USB sound card to work at all I have done the following: 1 removed pulseaudio 2 blacklisted the internal sound card 3 running aplay -l lists only the USB sound card (exactly what I need) The audio source block device ID must be left blank to work If I specify hw:0,0 or plughw:0,0 I get errors telling me that I am not using enough ports or am using too many ports. I think that it is looking at the SPDIF and MIDI ports on the USB sound card that I do not use. As always any advise is appreciated. Regards, John