Klarinet Archive - Posting 000202.txt from 2010/08

From: "Keith Bowen" <keith.bowen@-----.com>
Subj: Re: [kl] About clarinet acoustics
Date: Tue, 17 Aug 2010 06:30:11 -0400

Because of the temperature gradient between the hot air from your mouth and
the external temperature - which will be worse when the clarinet is cold,
not better - one should not expect an accuracy better than about a semitone
in these experiments.

And don't forget to do the end correction for the mouthpiece/barrel bit as
well as the half-clarinet.

When warmed up, the average temperature in the clarinet is about 25.5 C in
an room at about 20 C, and the sound velocity is then 346 m/s.

I think the mouthpiece node position will change somewhat between the two
measurements. I can't estimate how much, but my feeling is less than a cm.

Keith

-----Original Message-----
From: Jennifer Jones [mailto:helen.jennifer@-----.com] =

Sent: 17 August 2010 10:49
To: The Klarinet Mailing List
Subject: Re: [kl] About clarinet acoustics

Nitai,

The half clarinet measurement is easy. If you have a tuner that can
tell you what frequency you are playing. Perhaps if it just tells you
how many cents sharp or flat you are and relative to which frequency,
it should work. You 'll also need a thermometer and a ruler (metric
is nice).

The thought was to use just the upper segment of the clarinet, the
barrel and mouth piece, measure the frequency played (cold clarinet-
not warmed up) determine the wavelength corresponding to that
frequency for the air temperature you have. Then calculate 1/4
wavelength. Subtract that 1/4 wavelength from the length of your half
clarinet plus 0.6 times the radius of the end and you get the distance
between the tip of the mouthpiece and the first node in the clarinet.
It is the same calculation that Diego did earlier, but without the
complication of the bell.

http://test.woodwind.org/Databases/lookup.php/Klarinet/2010/08/000059.txt

Diego converted from concert A (B all closed with speaker key), which
wouldn't be possible with a half clarinet, unless perhaps from high B
(thumb, index finger, speaker key). I was thinking of setting the
tuner on C or C#, but I am not sure my tuner is that sophisticated.
Then there is the issue of converting cents to hertz, which it looks
like will be easy:

http://www.sengpielaudio.com/calculator-centsratio.htm
http://www.pianosupply.com/cents-hz/

-Jennifer

On Tue, Aug 17, 2010 at 2:29 AM, Nitai Levi <clarnibass@-----.com> wrote:
>>> It means I've been right to be dividing the 'effective clarinet closed
tube'
>>>(the
>>>
>>> distance between a little bit into the mouthpiece and slightly beyond
the first
>>>
>>> open tonehole) to estimate where bore modifications most affect the
>>twelfths:-)
>
>>> I don't have a thermometer -- and this IS Siena, therefore temperature
is
>>> important -- so the half-clarinet will have to wait.
>
>>> Tony
>
> How important is not to have curves in the bore, like a bass clarinet
neck? If I
> understand, bows are a bit similar to slightly enlaging the bore at that
point.
> At least on the saxophone bow, not sure about bass clarinet neck. Because
other
> than that, my bass clarinet is a straight cylidnrical bore and I can check
both
> just the top joint (middle C fingering) or both joints without bell (low
Db
> fingering) so it is just a closed pipe with no "last tone hole". I have a
> thermometer, even a funny one that looks like a pig :)=A0 I can also meas=
ure
> anything with half a soprano clarinet. I just need to know what to measure
:-)
>
> Nitai
>
>
>
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