The acoustics of stringed musical instruments are closely related to the materials from which the resonance body is made: the anatomical structure of the wood, the species, the nature of the applied finishes, the geometric shape. The objective of the work is to analyze and compare the acoustic spectra of 4/4 size violins of four quality classes (maestro, professional, student and school), covered with different varnishing systems. Thus, the studied violins were recorded during the interpretation of some musical passages, and the signal was analyzed comparatively. The type of varnish and the thickness of the film in combination with the anatomical structure of the wood, lead to changes in the rigidity of the plates both in the longitudinal and radial directions, producing a change in the acoustic spectrum and implicitly of the violin’s timbre.