Using the width of the lower bout as a proxy for the body plan or plantilla, Figure 7 shows the number of instruments made in each lower bout width. SE 127 is the smallest by far with a lower bout width of 233 mm. Romanillos describes this guitar as having a top of very rough quality which appears to be pine. The next larger group with widths between 282 mm and 285 mm are the small guitars from the second epoch, SEU 2, SE 77, SE 92, SE 103, SE 117, and SE 151A, as well as FE 7 made with a repurposed neck. FE 18 which has been cited several times as atypical, is the next largest with a lower bout width of 295 mm.
Figure 7: Lower Bout Width Frequency
For the remaining guitars, it is hard to distinguish discreet groupings representing plans of fixed dimensions. In his book, Romanillos uses a formula to estimate the area of the plantilla and groups the guitars of the first and second epoch into five sizes. The groupings created by using the estimate for area do not map exactly to an ordering based on lower bout width.
In Figure 8, lower bout widths are ordered in construction sequence. It appears that Torres employed a greater range of plan sizes in his first epoch while, in his second epoch, he more consistently built to a larger width.
Figure 8: Lower Bout Width by Construction Sequence
Romanillos highlights the difficulty Torres faced in obtaining woods and the likelihood that his construction was often influenced by the materials available. In a number of instances, the soundboard consists of more than two pieces and this is frequently true for the back. Rather than building to exact widths for a family of discrete plans, is it possible that Torres chose the width based on the woods available?
If Torres did not build to a set dimension for fixed plan sizes, the analysis which follows seems to indicate that he maintained the proportions of his plantilla for the full range of sizes. Torres set a standard for body proportions which is still emulated today. In the figures that follow, the relationship between body width and body length and the relationship between lower bout, upper bout, and waist width are examined. In this analysis, data for 83 instruments was used. Complete data is not available for three guitars and FE 2, the pear-shaped guitar, is excluded. Also excluded is SE 127 where Romanillos lists a width for the upper bout that is larger than the lower bout, an apparent error.
Figure 9 depicts the relationship between the width of the lower bout and body length. Lower bout width is highly correlated with body length with an R2 greater than 0.9.
Figure 9: Lower Bout Width vs. Body Length
Also well correlated is the relationship between upper bout and lower bout width with an R2 approaching 1.0 as seen in Figure 10.
Figure 10: Upper Bout Width vs. Lower Bout Width
Similarly, the width of the waist is highly correlated with upper bout width as seen in Figure 11.
Figure 11: Waist Width vs. Upper Bout Width
It appears that Torres was very consistent in his plantilla throughout his career and across the full range of instrument body sizes.
Modern Practice:
The relative proportions of Torres’ plantilla or body plan were remarkably consistent throughout his career but he built guitars in a wide range of sizes. The lower bout width, for example, ranged from 233 mm to 366 mm. In his first period of construction, Torres appears to have experimented more with body size while in his second period of construction he appears to have gravitated to a larger body plan of more consistent size. During this second period, he also built a number of smaller instruments but also more consistent in size.
When discussing body plan, the ratio of the upper bout width to the lower bout width is often cited. Based on the dimensions provided by Romanillos for Torres’ instruments this ratio averaged 0.76 and ranged from a minimum of 0.72 to a maximum of 0.78. Sheldon Urlik’s catalogue of his guitar collection offers a comparison for guitars built since Torres’ time. Based on the dimensions provided by Urlik (excluding the Torres and flamenco guitars), the average ratio is also 0.76 ranging from a minimum of 0.72 to a maximum of 0.80. The figure below compares the two catalogues.
Ratio of Upper Bout Width to Lower Bout Width Frequency for Torres vs. Urlik Collection
As can be seen from the histogram, the upper to lower bout proportion that Torres established for his plantilla has continued to serve as a model for modern makers.