Klarinet Archive - Posting 000920.txt from 2003/03

From: Tony@-----.uk (Tony Pay)
Subj: [kl] Bassoon and oboe reeds on clarinet bodies
Date: Sun, 23 Mar 2003 13:12:15 -0500

On Sun, 23 Mar 2003 07:31:09 -0500, gkidder@-----.org said:

> Tony,
>
>
> At 00:58 3/23/03 +0000, you wrote:

> > On Sat, 22 Mar 2003 19:11:52 -0500, gkidder@-----.org said:
> >
> > > We discussed this some years ago, and I reported that I had also
> > > tried the experiment, but with a contra-bassoon reed and a man who
> > > know how to play it. Even with this larger reed, the clarinet
> > > overblows an octave.
> >
> > In all parts of the register, George?
>
> As I remember it, we tried a number of different notes, and they all
> shifted an octave when the register key was opened. It was not so
> easy (so my bassoonist friend reports) to get the thing to sound at
> all, but when it did, the register key was an octave key.

[snip]

> So, vide your previous post, get yourself a bassoonist friend and a
> cork!

Yeah, I did, as previously promised. So, we tried a bassoon reed
(though not yet a contrabassoon reed, though we have a contrabassoon in
the ensemble next week.)

This bassoon reed was inserted into the top of a C clarinet barrel, with
the socket filled with blutak around the reed. (So, a jump
discontinuity of boresize at the top of the barrel bore, where the
mouthpiece usually takes over.) Period instrument, so few holes and
relatively simple tube.

In this first experiment, we didn't attempt to measure the pitch of the
lower register, though we'll perhaps try again tomorrow. (In fact, in
the next experiment, in order to make some comparison with the standard
pitch as played with clarinet reed plus mouthpiece, my idea would be to
join the bassoon reed to the slot of the mouthpiece in such a way as to
make the volumes of the two systems roughly equal.)

We found that the overblown pitch is highly labile, in the sense that
you can achieve an octave, and with a different embouchure also less
than an octave; but you can also bend the top note at least a fourth
higher without changing the mode of oscillation.

What that indicates to me is that the reed and tube aren't strongly
coupled, so the description 'overblows an octave' is undermined.
Something that overblows over such a wide range isn't really
'overblowing' at all.

Then we tried an oboe reed. This proved incapable of sounding any sort
of fundamental. The effect was of a reed 'crow' inside the clarinet
tube. In effect, the reed wasn't 'seeing' the clarinet tube, and its
behaviour was dominated by its own vibrational characteristics.

A narrower clarinet bore might give a different effect, but I imagine
that it would be equivalent to using a larger reed -- which we
already tried by using the bassoon reed.

In a way, I suppose none of this is surprising. Real instruments are
designed in such a way that the reed and tube vibrations are strongly
coupled, and it's that coupling that allows the simple mathematical
analysis to work.

Tony
--
_________ Tony Pay
|ony:-) 79 Southmoor Rd Tony@-----.uk
| |ay Oxford OX2 6RE http://classicalplus.gmn.com/artists
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