Javier,
> What's wrong with PVC and Kan octave??
Nothing on the face of it. The real question is aspect ratio and Kan
octave--whether it be be bamboo, PVC, nickel silver, hardwood, etc.
Second octave (and higher) is favored with higher aspect ratio numbers. To
review: the Aspect Ratio is the ratio of flute length divided by bore
diameter. This number needs to be 30 (or above) for a good second octave.
You mentioned that you have a D PVC shak. Assuming Schedule 40 PVC (bore
diameter = 20.6mm) it's length will be about 520mm to be tuned to D. Which
means your Aspect Ratio is a tad over 25--which makes the second octave
difficult at best. What to do? If you really want D then switch to Schedule
40 PVC which has a smaller bore diameter of 18.4mm. The length will be close
to the standard 545mm which will result in an Aspect Ratio of about 29.6.
To really understand this, take whatever PVC you're using and make a flute
with an Aspect Ratio of 32. Assuming 3/4" Sch 40 (ID 20.6mm) the length will
be 659mm. Second octave will be there nicely.
Second octave is helped by care in crafting the edge, playing technique,
etc. But if the tube isn't configured for second octave (as specified by
aspect ratio) it'll be a struggle forever.
Skinny bores favor the higher octaves--fat bores, the fundamental. That's
just the way it is and an AR of 30 seems to about the dividing line.
On one of my pages:
http://www.navaching.com/shaku/bore.html
I describe playing a tube with an AR of 85. Do the experiment and your
questions will be cleared up.
Nelson
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