Klarinet Archive - Posting 000604.txt from 2000/01

From: "Clark W Fobes" <reedman@-----.com>
Subj: [kl] Fw: Mouthpieces and Intonation
Date: Mon, 17 Jan 2000 22:32:07 -0500

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Sending this again. Operator error!
----- Original Message -----=20
From: Clark W Fobes=20
Subject: Mouthpieces and Intonation

It has been interesting to see Walter's enthusiasm for mouthpiece =
design. These are all questions that all of us who try to make superior =
mouthpieces must ask and understand. Bravo, Walter.

I may have misunderstood a point Walter was trying to make when he =
stated:

"If you have a mouthpiece with a bore that flares to 15.1 mm, and you =
put it=20
> on a Buffett R-13 with a 14.76 bore, what will happen????"
=20
Am I to understand, Walter, that you believe that the bore at the end of =
the mouthpiece (exit bore) should match the bore at the top of the =
barrel? And do you state that the bore measurement at the top of the =
upper joint is 14.76mm?
=20
14.76mm is the "nominal" bore of a standard R-13. This number refers =
only to the area of the bore in approximately the middle third of the =
instrument. The polycylidrical R-13 bore has two more steps in the top =
third of the clarinet that results in a bore at the top joint of about =
.587" give or take a few thousandths. (Not very consistent!)
=20
Before I go much further I would like to start speaking to bore =
dimensions in terms of .001" of an inch. This is a more widely used =
method among makers I have spoken to and is more meaningful to me at =
least. Multiply Walter's metric equivalants by 39 and we can reach a =
very close approximation to .001"
=20
15.1 x 39 @-----.589" (rounded up)
14.76 x 39 @-----.576" (rounded up)
=20
If you were to try to play a barrel with a top dimension of .576 on a =
Buffet R-13 you would be very unhappy. Most Moenning barrels are about =
.588 -.589 at the top and then taper to about .578-.579. Standard Buffet =
barrels start at about .588, but have
very little taper
=20
.589" is a little small for the exit bore of a mouthpiece unless you are =
using an old Chedeville style bore that has less taper and is a bit =
larger at the top bore than most of the Kaspar mouthpieces .=20

In my work I have found that mouthpiece bore dimension is not the =
exclusive influence on intonation. The barrel/mouthpiece COMBINATION is =
extremely important. One can correct some inherent deficiencies in a =
mouthpiece with a properly adjusted barrel. Most American players now =
favor a medium large bore
(like the Kaspar mouthpieces) and an inverted cone barrel.

Most *good* Kaspars that I have measured have exit bores right around =
.595". If one were to use a barrel with a similar measurement at the top =
the tone would be quite diffuse and (assuming a barrel length of 65mm =
-66mm) would be quite flat in the throat tones. A properly made inverted =
cone barrel balances the overall volume of the mouthpiece/barrel bore =
and will bring the larger bore mouthpiece into good modal ratios.

Walter is also correct about the problems of bore "warpage" during the =
cooling process. This is why it is absolutely essential to use reamers =
to bring the bore up to specs. I use 4 reamers when working on or =
checking the bores of my mouthpieces and they all have slightly =
different functions.

Another interesting aspect of adding a sudden reduction to the bore just =
below the mouthpiece is the introduction of a "choke" at the very top of =
the clarinet. A choke is a reduction step that creates turbulance and =
thus resistance. All Buffet R-13 clarinets also have a choke where the =
bell meets the lower joint. Chokes occasionally occurr where the upper =
and lower joint meet, although I find this to be a fault rather than an =
enhancement. The "positive" resistance that a barrel choke causes can be =
felt by the player as an additional "springiness" or :cushion.

My point is that one MUST consider the mouthpiece and barrel as an =
acoustical unit. The complexity of this acoustical system is compounded =
by the style of bore and tone hole design of each clarinet maker. The =
variations just spin on and on so that which we hope can be expressed =
scientifically still remains in the realm of art.

Clark W Fobes

>=20

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