Archive for the acoustical documentation of classical Spanish guitars, flamenco guitars and romantic guitars from private and public collections – bridge mobility

Abstract

This archive documents some of the acoustical characteristics of valuable and historically important guitars from the last 220 years. The archive contains guitars from Torres, Pages, Garcia, Simplicio, Contreras, Conde, but also from contemporary guitar makers such as Marin, Bellido, DeVoe. More than 60 guitars are documented, most of them classical Spanish guitars, flamenco guitars and romantic guitars. Most of the guitars are from Spain. Measurements were done with professional minimal equipment in the places of the private or public collections, with the upside of access to valuable instruments, and the downside of compromises in terms of a limited signal matrix and some impairment caused by the acoustical environment. The two-channel vibro-acoustical measurement at the bridge captures the two main degrees of freedom, while three more channels sparsely capture near-field radiation. This matrix is sparse, but good enough to analyze matters of symmetry/asymmetry, top plate mobility, and radiation efficiency. While early reflections and reverberation are unlikely to affect vibro-acoustical measurements, they are likely to affect the near-field measurement. Expected impairments are controlled by in-situ avoidance of early reflections from the floor and by clearance from reflecting walls. Documentation of wall distances allow adequate post-preparation of short reflection-free impulse responses. The documentation finally serves for archiving acoustical fingerprints of important guitars, which are likely to deteriorate eventually even under thoughtful preservation. It also serves analyses of individual guitars and, furthermore, analyses of the acoustical evolution across epochs of guitars.