For an introduction to the Lynar B3 manuscript, see http://partitura.org/index.php/heinrich-scheidemann-praeludium-e-moll/. The first complete anonymous piece in the Lynar B3 manuscript is a prelude in D, or perhaps better, primi toni. Although the composer is unknown, it is quite certain, based on the quality of the composition, that the composer is not for example Scheidemann. Nice as the piece may be, it has not the depth or thouroughness of a composition by one of the great early baroque masters.
The recording was done with the Hauptwerk software and the sample set, made by Voxus, of the Van Dam organ (1832) in Tholen (http://www.voxusorgans.com/en/tholen).
Score available here: http://partitura.org/index.php/anonymous-praeludium