The following text is an excerpt from the dissertation document entitled, An Examination of Commercial Clarinet Reeds with Regards to Design and Materials, copyright 2008, Blake McGee
STRENGTH: CONTRIBUTING FACTORS
Several important design factors that correlate to the manufacturers’ designation of strength were identified by this analysis. This is one area that the industry leaves up to the suppositions of the players and so is of great interest to this study. For instance, players often believe that reeds with a greater strength value have more wood in the “heart” and/or tip areas of the reed. Perhaps a more believable assumption is that reed strength is graded on the qualities of the cane; the denser the cane the stronger the reed. Or it may be that the cut vamp of each reed strength reed is designed significantly different from each other.
To examine these hypotheses, three categories will be considered separately: 1) cut of the vamp, 2) qualities of the cane, and 3) dimensions of the blank. For specific data, including p-values, refer to the correlation matrix in the index.
Cut of the Vamp
Several statistically significant correlations between the shape of the vamps cut and how a reed is sorted by strength were observed. However, it may not necessarily be the case that a manufacturer has a different vamp shape in mind for a given strength when making a reed. It is just as likely that the tolerances allowed with the reed-making machinery produce a range of vamp characteristics that eventually sort out to specific strengths. This is confirmed by the fact, as will be discussed below, that cane qualities play a more significant role in determining the strength of a reed than any vamp measurement. There are, however, some important characteristics of vamp shape that play a role in determining strength.
The values corresponding to the shape (aX2) and slope (bX) of the curves along both the center and rail lines tend to increase with a higher strength rating. Regarding shape, the higher the numeric value, the more severe this line is curved (a lower value represents a straighter cut from tip to rail). Similarly, the higher value for the slope of the curve, the more the cut is slanted towards the shoulders. It is difficult to draw strong conclusions to the meaning of these correlations, but here are two observable scenarios:
1) The sample of a softer reed will more likely have a straighter cut from tip to shoulders, but have a more gradual slope. This reed could potentially have less wood in the “heart” of the reed, as such, more area of the vamp would be involved in flexing, and therefore, would be more flexible overall. An example of this reed style is Rico Royal: employing a straighter, more gradual cut, and a thick tip.
2) This same reed could instead have more wood in the heart due to the fact that a straight curve that is sloped higher leaves more wood in the center of the reed. This reed would be less flexible in the center of the cut and would be more dependent on the tip’s flexibility. This reed style is utilized by Gonzalez: a severe curve and rapid slope corresponding to a thin tip.
Interestingly, there is no direct correlation between tip thickness and strength of reed (-.002). As described in the above scenarios, two similar strength reeds have greatly different tip thicknesses depending on other qualities of the cut. A reed with a thicker tip will probably have less wood in the central “heart” of the vamp than one with a thinner tip. In addition, the shape of the vamp of the reed is greatly dependant on the thickness of the blank (correlation equals .542). Blank thickness, however, does not correlate to the amount of wood in the heart area. So, strength correlates to vamp shape, which correlates to blank thickness, which in turn, correlates to tip thickness. Observe the flow chart below:
Notice that a soft reed with a thin blank will have a straighter cut, thus more wood in the heart, and more reliance on a thinner tip for function. (Rico is a prime example of this scenario.) Conversely, a hard reed with a thick blank will have a more severe shape to the curve resulting in less wood in the heart area. More of the vamp of the hard/thick-blanked reed is involved in vibrations and so it will in turn have a thicker tip (Olivieri is a prime example.)
While the above statements have statistically significant correlations, it is not the rule with every brand. Gonzalez, for example, creates hard reeds with a slightly thicker blank, straighter cut, and thicker tip than a soft reed (see appendix for specific data and curve comparison charts). This hard reed will have both more wood in the heart and at the tip, which breaks from typical strength associations. It should be noted, however, that differences in measurements from Gonzalez are extremely small between different strengths. Strength is mostly dependant on the hardness of the cane.
Qualities of the Cane
The strongest correlation to reed strength was found in the values represented by the crush test (.378). This measurement is the closest representation of cane density available for this study. It was found, with few exceptions, that the higher the reed strength designation, the higher the crush test measured. Standard deviations in crush test varied greatly between brands, implying that some manufacturers depend on cane qualities to determine strength more than others.
For instance, V-12 reeds had little deviation in the results of the crush test, and no strong correlations between strength and density. Instead, these reeds rely heavily on the shape of the vamp to determine strength while using highly consistent cane. On the other extreme, Rue Lepic 56 exhibited the largest deviation and range of crush test values, which also was its only important correlation to strength.
In fact, more variables are dependent on the result of the crush test than any other single measurement. These correlations will be discussed more in depth later.
Dimensions of the Blank
The most surprising correlation to strength is the ratio of vamp to bark areas (-.208). As the strength of the reed increases, the length of the vamp will likely be shorter, and the bark longer. Despite the seeming triviality of these results, there may be a logical explanation. As mentioned above, strength and the shape of the curve are correlated. A stronger reed will be more likely to have severe curve along the vamp as well as a greater slope. It makes sense that a reed with a shorter vamp will require a cut with a more severely shaped curve in order to span the decreased space between tip and shoulder.
Notice the following two curve graphs. Both graphs present curves that move from identical levels on the left to the same higher levels on the right. The only difference is the distance in which the change of thickness (height) takes place. All else being equal, the reed represented on the left will more likely have a stronger rating than the one on the right despite the same tip and blank thicknesses.
Other than the length of the vamp, there is no significant correlation between blank dimensions and strength. These values appear to be specific to each brand and consistant across strength within that brand. For example, Gonzalez makes all of their blanks with same dimensions regardless of which strength reed they will end up becoming.