Thickness Graduation Mapping:

Surprises and Discoveries






 By Jeff Loen, Kenmore Violins, Kenmore, WA

Presented at Violin Society of America Convention, Nov. 2003, Baltimore, MD





Top and back plates of Golden Age (pre-1750) violins, violas, and celli show a number of unexpected characteristics, based on compilation and mapping of thickness graduation patterns of hundreds of fine instruments.  Generally, the plates are thinner and less precisely carved than modern master-level work.  Overall plate structures are classified as uniform (common on top plates), concentric (common on back plates and some top plates), longitudinal (less commonly used on top and (or) back plates), and unclassified (irregular).  In addition, many classic Cremonese violins that are in demand by the best players have top plates that are carved in reverse of the usual pattern.  Rather than being thick between the ff-holes and thinning towards the edges (normal graduation), these plates display minimum values near the center and thicken towards the edges (reverse graduation).  An analysis of thickness distributions on Strad and del Gesú top and back plates shows that del Gesú plates are, on average, significantly thicker.  Moreover, some violins show asymmetrical graduations, although no systematic asymmetrical preferences were found.  Back plates by Stradivari and Guarneri del Gesú show, on average, a center of thickness at about the 50% mark, conforming to the position of small pin holes mapped on violins by three generations of the Amati family. 


For comparison, I include thickness maps of two poor sounding German factory violins in my collection. These extremely thick instruments were commercially unsuccessful until they were regraduated.  I also include maps of three fine master level violins, which show minimum thickness in the upper and lower bouts, and slightly increased thickness between the ff-holes and at the soundpost location.  These makers emulated the classic plate patterns, but avoided going too thin.


Acoustical effects of apparent “imperfections” of classic instruments such as very thin plates, reverse graduation, thickness mottling, and plate asymmetry are difficult to evaluate, although research suggests that these characteristics could possibly be beneficial to tone.




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