Klarinet Archive - Posting 000425.txt from 2004/06

From: Tony Pay <tony.p@-----.org>
Subj: Re: [kl] Nodes (was Mr Rosenberg posts, also was: Reeds)
Date: Sat, 26 Jun 2004 11:00:00 -0400

On 26 Jun, ormondtoby@-----.net (Ormondtoby Montoya) wrote:

> Umar=A0Goldeli wrote:
>=20
> > http://www.phys.unsw.edu.au/~jw/clarinetacoustics.html
>=20
> Thank you, Umar. The web site has exactly the information I was
> looking for.
>=20
> The answers weren't what I expected, but if I had known the correct
> answers, I woldn't have needed to ask in the first place. :-)

It's a very good site, isn't it?

A 'rule-of-thumb' statement is that the pressure nodes and antinodes of t=
he
second mode of vibration of a given fingering occur roughly a third and t=
wo
thirds of the way down the instrument from, I suppose, slightly below the=

mouthpiece tip to the first open hole of the fingering.

It's at those points that bore perturbations modify the relationship betw=
een
the pitch of the first mode of vibration and the pitch of the second mode=
of
vibration -- that is, between the 'chalumeau' and the 'clarinet' versions=
of
the fingering. Such perturbations are commonly said either to 'stretch t=
he
twelfth' or to 'narrow the twelfth' corresponding to the fingering.

Clarinets makers typically use such bore perturbations to counter the eff=
ect
of the register key, which clearly can't be in the optimal position for a=
ll
notes. But the relationships between the other modes of vibration of the=
se
and other fingerings are affected as a consequence (the pitch of altissim=
o
notes, for example); and the richness of the harmonic spectrum of the
chalumeau notes is inevitably compromised too. The upshot is that you do=
n't
want too wiggly a bore.

Benade, p474&ff, has a good discussion of the topic.

Tony
--=20
_________ Tony Pay =20
|ony:-) 79 Southmoor Rd tony.p@-----.org
| |ay Oxford OX2 6RE http://classicalplus.gmn.com/artist=
s
tel/fax 01865 553339
=20
... How many times do I have to flush before you go away?

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