Léon Berben Sweelinck’s keyboard works: were they perhaps played on clavichords?
Het ORGEL 100 (2005), nr. 3, xx-xx [summary]

Knowing that Jan Pietersz. Sweelinck’s works for keyboard need a compass up to a2, whereas they need lower notes in the bass than the organ of his time could provide, it seems obvious that this music was played on the clavichord. Earlier hypotheses, suggesting that these pieces were played on harpsichords, make less sense, as harpsichords have many notes above a2. The ‘clavichord-hypothesis’ is supported by the fact that organists used clavichords to study their art by playing model compositions, written by their teachers or other composers, in order to learn how to improvise on the organ later on. This supports the idea that to understand the large ‘organ works’ that Sweelinck and other composers wrote, one must first understand how they taught their pupils.