 The Clarinet BBoard
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Author: GBK
Date: 2009-03-10 02:53
I was discussing this topic with a colleague and we both realized that we do not know the answers to the following:
1. Should the dimension of the exit bore of the mouthpiece match EXACTLY to the entry bore of the barrel?
2. Should the dimension of the exit bore of the barrel match EXACTLY to the entry bore of the upper joint?
One would think (perhaps simplistically) that "non-matching" would create additional resistance.
...GBK
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Author: voodoosausage
Date: 2009-03-10 03:05
My opinion - it doesn't matter one bit - just find what sounds good.
My reasoning - instrumental acoustics is incredibly messy, and trying to predict how it would sound to any great level of detail based on this kind of geometry is ridiculous.
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Author: jsc
Date: 2009-03-10 03:16
Wouldn't the air hit the edges of the joints if the bore were smaller (ie mouthpiece to larger barrel and barrel to larger upper joint). If the bore size were the other way (ie larger mouthpiece to smaller barrel and larger barrel to smaller joint) then there should be a smoother flow. Interesting thought, though. I've never thought about this and now I'm curious to check all my mouthpiece to barrel joints. I am currently playing on stock barrels but am considering new ones sometime this year. This topic will make me reconsider some choices.
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Author: Alseg
Date: 2009-03-10 04:01
A step-off (narrower at the barrel entry and exit....ie mouthpiece exit is wider than the barrel entry, and the upper joint is slightly wider than the barrel exit) is NOT a big deal, and can have advantages.
So, the Answer to both questions is NO, but with one caveat....The mouthpiece exit bore should just about match. If the exit bore of the mouthpiece is wide (as it was on some Kaspars), then a matching barrel entry bore requires some narrowing of the barrel exit to maintain intonation in some clarinets (Buffet especially, but not in older Selmers). This is the origin of Moennig taper (Clark Fobes has a nice article about this).
http://test.woodwind.org/Databases/Klarinet/2000/01/000604.txt
Also, someone on the board once did a nice bunch of measurements correlating mpc exit bores (A Cicero Kaspar was one of the widest) and barrel entry bores.
Former creator of CUSTOM CLARINET TUNING BARRELS by DR. ALLAN SEGAL
-Where the Sound Matters Most(tm)-
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Author: Ken Shaw ★2017
Date: 2009-03-10 12:53
jsc -
Comparatively little air moves down the clarinet bore. The tone is produced when the vibration of the reed induces vibration (mostly from side to side) of the air that's already in the bore.
A change in the bore size (at the intersection of the joints) certainly affects intonation, tone and response, but not because it changes the flow of air. Rather, it affects the modes of vibration, moving the pitch up or down and promoting or damping various modes.
For example, the Moennig reverse cone barrel shape affects the pitch relationship between the chalumeau and clarion registers, bringing them closer to being in tune with one another. Kalmen Opperman tweaks the cone contour of his barrels (which I play), producing remarkable improvements in tone and response by making tiny adjustments.
Similarly, the R-13 polycylindrical design corrects intonation and response problems inherent in a straight cylindrical bore.
I have a very fine Eb barrel from Kal in which the bore is about 25% smaller than the mouthpiece and center joint. When I asked him about this, he said not to worry about the size, but only whether it works.
The upper end of the bell always has a significant contraction. The theory is that this enhances the vibration of the air column by strengthening the node at the bottom of the bore and reflecting vibrations back up the bore. Whether or not this is so, it certainly does something, and removing the bell contraction ruins the response.
This sort of tweaking is universal. For example, the 7th harmonic is strongly non-harmonic (and out of tune) with the fundamental. Therefore, piano hammers are positioned to strike the strings at a point that dampens that harmonic. This was discussed here several years ago but a quick search didn't locate the postings. See, however, http://halflightphotography.blogspot.com/2009/02/middle-c.html.
Ken Shaw
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Author: David Spiegelthal ★2017
Date: 2009-03-10 18:29
What Ken said. To oversimplify, in a clarinet we are mostly trying to generate nice standing waves that live inside the tube, with actually very little airflow moving through the instrument, unlike an automobile exhaust or garden hose. Gaps, steps, or gradual changes in bore size mainly affect the frequencies and shapes of those standing waves (translating to pitch and tone quality of the individual notes) with much lower-order effects on damping of those waves (resistance as sensed by the player, and/or dulling of the tone as perceived by the listener).
The bottom line is, bore-matching between mouthpiece/barrel/upper joint, and slight gaps between these, have less effect on performance than you would intuitively expect.
I think that's more or less correct.
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Author: Don Berger
Date: 2009-03-10 18:57
As a Chem Engr, I/ we had courses in Flow of Fluids in college, which helped my understanding and practice in the petrolem /chemical industry, still recall some of the important Reynold's Numbers !! Granted the diffs in velocity in a cl's bore and Nat Gas lines, I view our/these ?'s ?inversely?, "why create sudden enlargements/decreases in flow path, which we know produce turbulence, at least at higher velocities, if it can be easily avoided" . We go great lengths in design of velocity metering, venturies and orifices . I've not heard of substantial tonal/response improvement due to bore steps. Comments? PM thots, Don
Thanx, Mark, Don
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Author: Alseg
Date: 2009-03-10 19:07
By constricting at certain places, we change where the nodes occur. This alters the effect of tone holes. We capitalize on that by noting a "defuzzing" in the throat tones, for example.
Former creator of CUSTOM CLARINET TUNING BARRELS by DR. ALLAN SEGAL
-Where the Sound Matters Most(tm)-
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