I am gradually working up to having a better sound recording setup. One concern is the computer used to do the recording; computers usually have fans that sometimes fire up at unexpected moments, and for sound recording you need quiet.
The Raspberry Pi has given me a lot of fun already for amateur radio, and I wondered if the most powerful version I have – the Raspberry Pi 3 model B – would be sufficient to make overdub recordings. Online research suggested that at least some people had made the Raspberry Pi work for sound recording, and there are versions of Digital Audio Workstation software that can run on it, for example https://www.youtube.com/watch?v=V2MTUpji8Uw&feature=youtu.be
I installed Audacity (as a simple recording system that I am familiar with) on the Raspberry Pi (simple, using the package installer) and it seems to work. I set up a quick and easy system (which I can test with until I get a proper usb sound interface), using a cheap mixer to provide phantom power to the microphone, and a cheap usb sound dongle to provide the audio interface to the Pi. It looks like this:
For those not familiar with it, the Raspberry Pi computer is the small bare circuit board left centre. (I have ordered a box for it!) The sound dongle is plugged into the powered usb hub (as is the mouse) just below the monitor.
I recorded a click track, and overdubbed it onto itself to determine the latency correction needed; this is easy in Audacity (and well documented). I then recorded a track with the nyckelharpa, and overdubbed a second part with the fiddle. It was OK, in that I could monitor the first track on headphones whilst playing, but a proper usb interface will enable me to monitor both properly in the headphones. Watch this space!