 The Clarinet BBoard
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Author: rtmyth
Date: 2012-10-20 13:36
Whar Determines it? Material, dimensions, or ? Is there a standard?
richard smith
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Author: Paul Aviles
Date: 2012-10-20 13:55
It is kinda "all of the above." In addition, the only 'standard' is that a 3 in one brand should be harder than a 2 of the same brand (even then, out of a box of ten you're looking at an average rather than each reed being the exact same strength).
Keep in mind what we're talking about is essentially a blade of grass. There will always be variations from one to the other......like snowflakes.
As you get deeper into the whole knot, there are 'tendencies' within different kinds of cuts (hearts that are more crescent shaped versus one that is more of a strict "V" shape, or longer vamps versus shorter ones, wider reeds versus more narrow ones, etc). But what it comes down to is what works best with you and your mouthpiece.
.................Paul Aviles
Post Edited (2012-10-20 13:59)
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Author: rtmyth
Date: 2012-10-20 15:38
Paul, what i are the criteria for synrhetics?
richard smith
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Author: gsurosey
Date: 2012-10-20 20:49
For cane, isn't it the density that determines the strength?
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Rachel
Clarinet Stash:
Bb/A: Buffet R13
Eb: Bundy
Bass: Royal Global Max
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Author: kdk
Date: 2012-10-20 21:04
Within the same brand and model, yes. The difference between a V12 3-1/2 and a V12 4 is stiffness of the cane, which is mostly a difference of density. The strength is sorted after the reeds are cut.
Between different models of the same brand or different brands, resistance differences can be because of the design of the reed itself. When players find one brand of #4 to be stiffer than a #4 of another brand, it's likely to have to do with the way the reed is cut. V12s are designed with a different profile from those of Gonzalez FOFs or GDs or even 56 Rue lepics and VD Traditionals ("Blue Box").
Karl
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Author: Paul Aviles
Date: 2012-10-20 23:54
Richard,
I would say that synthetics are more consistent from reed to reed of the same brand and strength (with Legere being most consistent of synthetics that I've used). And yet there are still variations from one to another. You just have to dive in and get used to the reed. Keep in mind even synthetics will lose their usable resilience (mostly in the upper most register) within four months or so.
.................Paul Aviles
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Author: kdk
Date: 2012-10-22 01:20
I wish this article were more explicit about a couple of things.
For one thing, what does the author mean by a "crush test?" I've read that manufacturers determine cane density with a gauge that pokes probes into the butt end of the reed (hence those little holes). The only affordable tool I've found available is the flex gauge by Uhl that tests the ease with which the tip bends. So, I wonder what tools Blake McGee used - maybe he explains more in the full dissertation.
For another, he seems to be saying that Vandoren cuts its V12s differently to produce reed strength variation, while it relies almost exclusively on density of the cane to determine the strength of 56 Rue lepics. Aside from my having read for as long as I can remember that most if not all (including Vandoren) reed mass producers grade their reeds for strength after they are cut and don't cut softer reeds differently from harder reeds (of the same model design). It's hard for me to imagine Vandoren using two different systems, since determining strength through profiling the gradations differently would require separate machines for each strength designation.
Do you know where to find the full dissertation? A little poking around on Google only got me back to the excerpt you cited. He apparently teaches clarinet at U. of Wyoming. I can try contacting him there.
Karl
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Author: Bob Phillips
Date: 2012-10-23 01:52
Two material parameters determine the resonant frequency of a reed. Those are the stiffness (how far the material will deflect for a given load), and the density, how much a volume of the material weighs.
The resonant frequency can be stated mathematically as:
Fnatural = SquareRoot ( Stiffness / Density ) x shape factor.
The ratio of stiffness to density is called the material's specific stiffness.
The shape factor depends upon the cube of the reed's thickness, the length of the lay of the mouthpiece to which it is clamped.
If the shape is constant for two reeds, the material (specific stiffness) will determine the character of the two reeds.
If a particular sample of material has a different specific stiffness, the shape has to be altered to make the reed play the same as one made of a different material.
A reed can be made stiffer by changing either the material and/or its shape.
With cane (and many other materials) stiffness and density are related.
Bob Phillips
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Author: kdk
Date: 2012-10-23 13:04
Bob, I ask the questions below with no intent to challenge what you've written. You've piqued my curiosity.
Bob Phillips wrote:
> Two material parameters determine the resonant frequency of a
> reed. Those are the stiffness (how far the material will
> deflect for a given load), and the density, how much a volume
> of the material weighs.
How does resonant frequency translate to a specific reed strength?
How is the stiffness measured? Is there some accepted standard deflection force? The reed would, I imagine, deflect farther if the fulcrum from which the deflection occurs is farther from the reed's tip - the longer the portion of the reed that's free to move, the farther a given force could deflect it. Is all of this standardized by the reed manufacturers? How is this measurement of stiffness done?
>
> The resonant frequency can be stated mathematically as:
>
> Fnatural = SquareRoot ( Stiffness / Density ) x shape factor.
>
> The ratio of stiffness to density is called the material's
> specific stiffness.
> The shape factor depends upon the cube of the reed's thickness,
> the length of the lay of the mouthpiece to which it is clamped.
>
What thickness is used? The thickness of the uncut part of the blank? The thickness at some point along the heart of the vamp (and which point)? What's the mathematical relationship between the reed thickness and the curve length?
> If the shape is constant for two reeds, the material (specific
> stiffness) will determine the character of the two reeds.
Shape in a reed's design involves a good deal more than its central thickness (wherever that is measured). There are a number of areas where taper rates can differ and points all over the vamp where, for example, a GD or a 56 Rue lepic is meant to be thicker (or thinner) than a V12 or a Reserve Classic. How do these differences in shape factor in?
I'm interested in how these mathematical relationships, which I've never read about before, apply in practical settings.
Karl
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Author: Paul Aviles
Date: 2012-10-23 13:14
The thickness of the butt of the reed is a highly under rated factor. If you really look at a reed, the amount of material you have in the heart is DIRECTLY related to the overall thickness of the reed. This is why German reeds (and I mean REAL German reeds not those we buy in the States called German) are so much thicker. This density is key when you have a long vamp in relation to such a small tip openning. Of course the reed quality becomes more critical in these extreme examples and may explain why a vast numvber of Viennese professionals are much quicker to move to synthetics to solve their problems.
....................Paul Aviles
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Author: Donald Casadonte
Date: 2012-10-25 16:50
Sorry, but don't get me started on this topic. Each reed companies use its own uniform methodology for rating reed strengths, but none of them is very accurate. There is no easy way to get at reed strength. Arundo donax is a viscoelastic material. It has a complex (as in real and imaginary parts) moduli, which is characteristic of viscoelastic materials. It makes modeling easier to assume that the modulus is quasi-isotropic, but because of skewing in the cut and distribution of lignin within the reed matrix, one can get large fluctuations within the reed. There is a way to determine all of this spectroscopically, but no one has built such a device (actually, not that hard using modern chip technology).
The best be can do is talk about an average strength for a reed, which is something like a bulk modulus. The best reference on the subject is:
Viscoelasticity of the giant reed material Arundo donax, by Arthur E. Lord.
A copy of his paper (not the whole book) may be found, here:
http://www.springerlink.com/content/lq3b04lyh3gwj20f/
and my dissertation (chapter 4).
I have been corresponding with Dr. McGee and I respect his work. We do disagree, I think, on whether or not tip thickness influences reed strength. Although it gets swamped out by other factors, in the standard thin plate theory, there is a correlation between thickness and apparent modulus for very thin plates (which describes the reed tip).
Here are some additional links to his research:
http://www.clarinet.org/pdfs/competitions/research-abstracts/2009/McGee%20Abstract.pdf
http://reedhelp.wordpress.com/research/
His dissertation, which is not yet online (I have a copy he sent me), is:
An Examination of Commercial Clarinet Reed Properties with Regard to Design and Materials
Donald Casadonte
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Author: Ed Palanker
Date: 2012-10-26 00:28
Sure it's the way the reed is cut, tapered and how thick the blank is that's makes one different from another but when all's said and done it's the quality of the cane and that can vary from year to year the same way that fine wines vary when there's to much sun, not enough sun, to much rain, not enough rain, etc. No two pieces of cane are the same no matter how the reed is cut. There's a reason a really fine wine sells for $100 a bottle and $20 the next. It's mother nature.
ESP eddiesclarinet.com
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Author: Bob Phillips
Date: 2012-10-26 02:04
Kdk.
No worries, I've grown a tough skin.
That shape factor in my earlier note is a complex thing that summarizes all of the shaping of the reed.
Here's a link that shows the formula for a simple "diving board" approximation to a single reed. (I offer this as a way to provide a clear picture of the "math model."
<http://en.wikipedia.org/wiki/Deflection_%28engineering%29>
It applies to the part of the "diving board" that sticks out of its mount.
Here's another link that gives the formula for the term "I" in the deflection formula:
<http://en.wikipedia.org/wiki/List_of_area_moments_of_inertia>
Scroll down to the "filled rectangle with base width b and height h"
Putting the two together gives an approximation to the behavior of the reed.
deflection = [ force_applied x free length cubed ] divided by [reed width x reed thickness cubed divided by 3]
A definition of stiffness is the ratio of force to deflection. In the case of a single reed, the load is spread over the flapping part of the reed by the air pressure in your mouth, the thickness tapers, and the thickness is not constant across the width of the reed, and as the reed wraps around the curve of the lay, the shape of the stuff left to flap and the loading that acts to bend the reed shortens.
Still, the general contributions to reed stiffness are:
Stiffness increases dramatically with the reed's thickness.
Stiffness decreases dramatically with the length of the mouthpiece lay.
We know these to be true because we use harder reeds on longer lays, and we thin our reeds to make them easier to play. That we thin one side or the other to balance the reed demonstrates how things change as the thickness changes across the width of the reed.
That term E in the first equation is Young's Modulus of Elasticity, and it is determined by standard methods. One way is to make up a simple rectangular beam of the stuff, support that test piece at each end and push down on it in the middle. Then, by measuring the applied load and the corresponding deflection, a formula similar to the one given above for the "diving board" can be used to back out the materials "E" value.
All this discussion considers deforming the reed statically, but in playing the reed moves, and the momentum of each bit of the reed depends upon the mass of that bit. That mass is given as the product of the volume of the bit and the material density. The assumption is that the density is the same everywhere, and that is why the ratio of stiffness (the E) to density --specific stiffness will factor out of the vibration frequency equation, separating the reed's material properties from the reed's shape.
If this is unclear, please ask me to wave my hands some more.
Bob Phillips
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