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I'm having difficulty finding any online equation for calculating the
hole positions for a pvc clarinet. I have made the following instrument
and I now wish to make another in a different key -
I presume the pitch at a hole is related to 3 parameters - the length
and diameter of the pipe, and the diameter of the first open hole from
the mouth piece. By adjusting the diameters of the holes in my last
instrument I was able to tune it. Can anyone supply me with the
equation? (I'm hoping I don't have to buy a book in order to obtain
what should be freely available to everyone) I have the instrument
built and now I simply need to drill the holes.
Thanks very much for your help,
A rough answer is that the hole shortens the pipe to the position of the
In other words if you put a hole in the middle of the pipe you should get an
octave change. This may be different for a clarinet since it also has the
peculiarity of breaking to the 19th semitone rather than the twelfth. Hmm...
In actuality I think a hole at the mid-point will give a bit less than an
octave, and the exact pitch is size dependant.
To some degree you will have to experiment. Boehm (sp??) wrote about it in
his book on the development of his flute. He opted for very large holes and
used pads instead of fingertips.
I really don't think there is an "equation," just approximate positions and
tuning until you have a working model.
The main thing is length. Small diameter long pipes tend to break to their
harmonics more easily. The tabor pipe has a very small diameter compared to
Flutes are considered open at both ends and the clarinet acts as if it is
closed at one end, which leads to it sounding an octave lower than a flute
of the same length. Tapered bores sound at the same pitch as a flute would
even if they are closed at one end, like an oboe or bassoon.
I would try tuning a simple flute for practice since it is the easiest
instrument to make, or maybe a kena, which is a knotched flute.