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

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.

PACS                                 43.75.Gh

File Overview

Title_Abstract.pdf                                     title and abstract
Method.pdf                                               documents method and measurement setup
List_of_guitars_description.pdf                documents the identification, provenience, material, type of guitars
List_of_guitars_physical_measures.pdf   documents geometry and other ohysical properties
Comments.pdf                                          few general and particular comments on mobility plots

AcousticLabHAW_Hamburg.jpg              documents the measurement venue according to the list of guitars
Archive_Romanillos_Siguenza.jpg          dto.
Avalle_Studio_Granada.jpg                     dto.
CentroDocMusAndalusia_Granada.jpg   dto.
ClassRoomSchool_Freiburg.jpg              dto.
ForumFinkenau_Hamburg.jpg                 dto.

260 x *.jpeg                                              documents individual measured guitars in their setups
63 x bridge_mobility_g*.jpeg                    documents the bridge mobility of 60+ guitars (see list above)
bridge_mobility_legend.jpeg                     legend for the bridge_mobility_plots

batch_extract_bridge_mobility_archive.m     MATLAB code, batch file, to be called by
create_fig_archive.m                                      MATLAB code, batch file, for the generation of transferfunctions
qualified_selected_impulses.mat                   original, qualified raw data, organized as simple MATLAB matrix

Instrumentation_DYTRAN_5800SL.pdf      data sheet of impulse hammer
Instrumentation_HEIM_DIC6                      data sheet of A/D frontend
Instrumentation_KISTLER_8778A500        data sheet of acceleration sensors
Instrumentation_ROGA_MI17                     data sheet of microphones