I’m trying to install a Mixpre-D as the USB audio device on a Raspberry Pi-2 (Jessie). When I run the command “lsusb” it’s not on the list of devices. However, it shows up on ALSA mixer. Using the Nano editor, I wrote a .conf file to change the slot assignments so that that USB audio device is now the default device (=0) and the internal PCM card is now =1. However, ALSA mixer still has no control of the Mixpre. Also the Mixpre is still not showing on the RPi-2’s Preferences-Audio Device Settings. This technique is supposed to work for some USB sound devices. What am I missing? Does anyone know if the Mixpre will even operate on a RPi-2? I’m reading that not all USB sound cards will play nice with a Raspberry Pi. Sound Devices says that the Mixpre must operate in “full speed” mode when connected by USB to a Linux system. They instruct to hold the headphone knob down and reconnect the USB. RPi’s don’t seem to like devices to be hot-swapped. So maybe that’s the problem.
Further more, does anyone care to offer some tips on what I’m trying to accomplish. I make nature recordings, and I’ve been asked to lead “sound walks.” I would like for participants to hear my microphones on their cell phones by tapping into a live stream that I create and transmit with a portable WiFi access point (a LAN set for static IP). Participants would connect to my LAN and hear the live stream from a static web page as soon as they opened their browser. I can’t find an intermediary device between the Mixpre and the WiFi router, and a friend suggested that I build one with a Raspberry Pi-2. Of-course I have yet to find anyone who’s done this kind of thing before. Doing some research, it seems that a Raspberry Pi-2 could do an adequate job. I was reading that the WebRTC protocol is now on iOS devices and Android, and that the RPi -2 will operate as a UV4L server, so quality and latency should not be an issue. Some basic requirements for the whole rig is: 1. that it must be small and easily powered by battery (4 hours max), 2. that it have only one function (power up and play - no monitor, keyboard or mouse required to initiate), 3. not require an internet connection (‘cause there won’t be one available out there), 4. participants not be required to install an app (‘cause that’s a pain in the ass, and too many of them will have trouble doing that anyway). I’m in over my head on this, but I like to learn about new things, so this seems like a fun and reasonable project. Any thoughts, tips, pitfalls to avoid, etc? Much appreciation in advance.