Klarinet Archive - Posting 000336.txt from 2004/06

From: GrabnerWG@-----.com
Subj: Re: [kl] Concentricity of barrel bore to upper joint bore; was: Round?
Date: Mon, 21 Jun 2004 16:33:26 -0400

Ormondtoby says:

<<Thank you for the reply, Walter. It happens that I wasn't measuring
concentricity, **but** it is interesting to hear one more reinforcement
of the idea that *area* (of each cross-section) is the controlling
factor, not shape>>

Both the total volume and the shape are "controlling factors".

With a barrel you have bore length and shape to work with. When you alter
either you also alter volume.

Volume controls general pitch level. Shape controls modal ratios (or how your
12ths tune). Reaming different locations of the barrel bore influence the
upper joint modal ratios greatly.

It is somewhat of a tragedy that the "best" tone and the "best" intonation
can result from two different tapers and sets of measurements. In other words,
the best barrel with the best tone does not necessarily have the best
intonation, and vice versa.

I made (and still have) a barrel for my A clarinet that produces just near
perfect 12ths. But - the tone is small and somewhat constricted.

A big part of the problem is that almost all of us play with mouthpieces that
end in a 15 mm ending diameter. We love the bigger, "darker" sound that these
mouthpiece produce. Our clarinets do not have that large a bore and therefore
often benefit from a Moennig-like reverse taper bore.

If you want to search the sneezy archives you will find some excellent
discussion of these issues. See Clark Fobes' submission on this topic, it is
excellent: http://test.woodwind.org/Databases/Klarinet/2000/01/000601.txt

Ormondtoby continues:

<<It happens that I was measuring the bore's diameter, and then rotating
the barrel 90 degrees around its longitudinal axis, and then measuring
it again (at the same end). The two measurements did not agree, thus
showing that my barrel's bore (which came from the factory, and I'm
*not* intending to mess with it!) no longer has a circular
cross-section. This is what I meant by "out of round".>>

Maybe it never did. But it is more likely that it warped with use.

<<I also noticed that the barrel's bore at the end next to the joint truly
*is* smaller (by ~0.15 mm in my case) than the bore of the joint's
tenon, thus confirming that there is a "choke" at the lower end of my
barrel.>>

You can confirm this by measuring the exit bore of the barrel and the entry
bore of the upper joint - OR - turn your clarinet upside down (sans mouthpiece)
and visually inspect by looking up through the bore toward a light source.
The choke is fairly easy to see.

Walter Grabner
http://www.clarinetxpress.com/
World-class clarinet mouthpieces.
Repair and restoration services

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