Soundboard Fractures in the Bent Side/Cheek Corner of Harpsichords

The following study is the result of an investigation over several years, seriously because the 2025 Eaton fire interfered substantially. It was prompted by a comment in the Jackrail Forum communications by Domenico Statuto regarding an internet publication by Geert Karman (see later footnote) who (Statuto) raised questions regarding its complete correctness. While lacking in some details of analysis, Karman’s major contribution for was—in my observations—an apparently widely missed structural issue of the classical instruments (apparently mostly of the French double manual type), namely the weakness of the right side of the instrument because of the corner configuration at the bentside/cheek connection, as compared to the stiffness of the spine under the overall bending induced by the string tension. This deficiency leads to the development of cracks in the soundboard near the bentside/cheek corner. Such cracks—sometimes referred to as “cracks obligatoires”—can be avoided if the “in-plane” rotation of the cheek is eliminated or reduced appropriately by using one or several of the means discussed in this paper The presentation covers a rational development for potential alleviation of such cracks, though I have become aware of multiple statements by harpsichord builders and repairers that such cracks do not, apparently, impair the sound of these instruments noticeably. Following a review of an early version of this writing Domenico Statuto pointed out that David J. Way had designed a reinforcement of that corner in a two-manual Zuckermann French Model similar to what had been considered here in section 8: it was interesting to learn that in its life time that instrument (and presumably other models of that type) did not develop “cracks obligatoires” of the kind discussed in this presentation (ref. comments near the end of the Appendix).