Klarinet Archive - Posting 000314.txt from 2001/06

From: "Diane Karius" <Dkarius@-----.edu>
Subj: [kl] Re: Tuning rings
Date: Thu, 7 Jun 2001 17:21:31 -0400

>>> DGross1226@-----.com wrote (greatly truncated)
Indeed, but on a 1950 low Eb Selmer Paris bass clarinet...
To lower the pitch, I found fibre washers at my local plumbing supply =
store=20
that were perfect as far as the outside diameter goes.... He replied, =
"Did you notice that the inside diameter of your tuning rings is at least =
1/16" smaller than the bore of your mouthpiece. You've had some really =
stuffy notes, haven't you?" Removing the washers eliminated all the =
stuffiness. Never underestimate the need for smooth air flow.
********
Warning: Science spoken below! =20
I'll add another caveat: never underestimate the effect of a decrease in =
radius... =20
Since the equation for resistance is:
R =3D (8 {viscosity}{length of the tube})/({radius to the fourth}{pi})
a small change in the radius has a LARGE effect on the resistance to flow. =
=20

The stuffiness is then due to both changes : =20

1) the turbulence produced by the edge of the tuning ring i

2) The 1/16" decrease in the bore (radius or diameter?) will have a =
significant effect on the resistance to airflow without the turbulence. =
Using the numbers for the I.D. of a Buffet R-13 (couldn't find numbers for =
the bass clarinet), I did the math on what that tuning ring would do to =
the resistance when it decreases the radius of the bore of the clarinet. =
=20
If the diameter of the bore was decreased by the 1/16th inch (i.e. =
1/32" of the ring sticking into the bore all the way around), the blowing =
resistance of the clarinet itself increases 59%
If the radius of the bore was decreased by 1/16" (i.e. 1/16" of the =
ring sticking into the bore all the way around), the resistance increases =
by 260%! =20

Adding turbulence into the mess only makes it worse, but I avoided that =
because the equation becomes non-linear and the math is way beyond a =
foolish physiologist such as myself :-)! =20

Since you have a series of resistances down the length of the tube you =
add all the resistances together to get the total resistance. The =
greatest resistance is still at the mouthpiece tip with the reed, so that =
dominates, but you've added a substantial amount of resistance to the =
clarinet just by decreasing the bore by that little amount in that one =
place. =20

Diane R. Karius, Ph.D.=20
Department of Physiology
University of Health Sciences
1750 Independence Ave.=20
Kansas City, MO 64106
(816)-283-2219
dkarius@-----.edu
www.uhsweb.edu/physio

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