Here's a great article "Saga of a Folksong Hunter", written by Alan Lomax and published May 1960 in HiFi Stereo Review magazine.
It tells the tale of Lomax's travels around the world recording and preserving the cultures that existed.
For a little background, the first tape recorder that he refers to would seem to have been a Brush Soundmirror which "disintegrated".
When in Europe, the Magnecord he used was mono.
And once he began to record in stereo, an Ampex 600 portable was to become the machine he used.
http://www.culturalequity.org/alanlomax/ce_alanlomax_saga.phpBTW, if you've never checked out the "Cultural Equity" site that is maintained by his heirs, there are other fantastic articles not to mention some 10k+ audio files including Lomax's earliest recordings.