Klarinet Archive - Posting 000207.txt from 2010/08

From: Jennifer Jones <helen.jennifer@-----.com>
Subj: Re: [kl] About clarinet acoustics
Date: Tue, 17 Aug 2010 11:03:08 -0400

Nice.

Would you share what make and model your clarinet is?

The "0.6 times radius of the end" is the end correction for a cylindrical p=
ipe:

L + 0.6a,
where
L =3D length of instrument
a =3D radius of bore at the end

We got this from the flute end correction. The length of the
instrument plus 0.6 times the radius of its bore. We used it because
there is no good mathematical model for end corrections in instruments
with bells or flares.

see:
"End corrections are more complicated in real instruments" at
http://www.phys.unsw.edu.au/jw/musFAQ.html#end

On Tue, Aug 17, 2010 at 6:14 AM, Nitai Levi <clarnibass@-----.com> wrote:
>>> Before doing more measurements it's sensible to see what has already be=
en
>>> done! Please see my long email about Vanderveen's book.
>
> I used to have that book but for some reason can't find it anymore.
> Unfortunately I also remember next to nothing from acoustics and instrume=
nts'
> acoustics classes in university. I might read that email but I'm writing =
here
> more to offer measuring what others were interested in and no so much to =
find
> out myself.
>
>>>The half-clarinet measurement would be interesting, though. Measure the
>>>bore diameter as well=A0to do the end correction.
>
>>> Oh and you need to measure temperature inside the bore. And until the
>>> clarinet warms up, there will be a big temperature gradient inside it.
>
> OK,=A0I assembled the mouthpiece (with reed), barrel and upper joint. I l=
et it sit
> outside in the room and put a thermomoter=A0next to it. I don't have a be=
tter
> method to measure the temp.=A0It's approx 27.5c. The length is approx 341=
mm (with
> I think +/-0.5mm is about right). The frequency is just a tiny bit over 2=
57.8
> hertz.

257.8 Hz should correspond to a very flat chalumeau D
(http://www.sengpielaudio.com/calculator-centsratio.htm said C4 -25.5
cents)

> The bore of this clarinet is (as accuate as I can measure): 14.76mm at the
> bottom of the upper joint, 15.10mm at the top of the upper joint.
>
> So doing the same calculation as Diego, the (1/4) wavelength for this is =
almost
> 337mm. That's only 4mm less than the length of the clarinet upper joint
> including barreland mouthpiece. If also doing=A0"plus 0.6 times the radiu=
s of the
> end" (which I'm not sure what this is at all) then it's about 8.5mm diffe=
rence.
>
> Nitai
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