Christian Erbach, Ricercar primi toni
Another one of the pieces from the organbook of Matthias Rottenau (Mus. Ms. 40615 from the Staatsbibliothek zu Berlin) that is probably possibly perhaps a Ricercar (see here for an explanation). It is a 4 voice fugue, however, the four voices seldom sound at once. Nevertheless, it is a well crafted piece, equally pleasant to play as to listen to.
Update (20-01-2018): it turns out that this is the first half of a Ricercar by Christian Erbach.
The recording was done on the sample set of the Bader-organ in the Walburgiskerk in Zutphen by Sonus Paradisi for Hauptwerk.