Klarinet Archive - Posting 000187.txt from 2002/11

From: Daniel Leeson <leeson0@-----.net>
Subj: [kl] [Fwd: Re: Overblowing]
Date: Mon, 4 Nov 2002 09:41:41 -0500

In a recent posting, I made reference to overblowing on instruments that
have additional keys, generally put there for low notes. For example, I
made reference to use of the low E-flat to get a B-flat when the
register key is despressed. I went further and spoke of the low D,
D-flat, and C on extended bass clarinets suggesting that using those
notes with the register key was generally unsuccessful.

Steve Fox of Canada wrote an interesting note to me on the phenomenon
and I asked him if he would permit me to post it. Instead, he wrote a
much more lucid description of that matter and has granted me permission
to post it on clarinet. I mention that on the basset horn that Steve
made for me, I use the low E-flat as a middle register B-flat all the
time because the tuning is perfect.

Here are Fox's comments.

========================================
The tuning of the twelfth for a given fingering depends on the location
of the register hole relative to the optimum position for that note. In
principle, each note of the scale should have its own register hole;
making do with a single one causes tuning problems at the top and bottom
of the scale.

If the register hole is ideally placed for a particular note, the
twelfth will be of minimum size (it's not guaranteed to be perfect; bore
shape and cutoff frequency also affect it). The further away the
register hole is from its ideal location, the wider the twelfth will be.

Thus, for the bottom notes of an extended range clarinet, the normal
register hole is so much higher up the body than it should be, that the
overblown notes are hopelessly sharp. A good register hole for bottom C
would be located somewhere around the left hand second finger hole.

The widening of the twelfths is exacerbated as the size of the register
hole (or more precisely, the diameter of the hole relative to the length
of the register tube) is increased. Making the register hole function
also as a tone hole for throat Bb forces it to be oversize, which
worsens the problem of the wide twelfths.

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**Dan Leeson **
**leeson0@-----.net **
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