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#1 2010-08-27 09:18:26

Colyn Petersen
Member
From: Omaha, NE
Registered: 2009-11-20
Posts: 46
Website

What primarily determines large vs. small bore

When designing a flute, what determines what is considered large vs. small bore? Can it be governed largely by the choke point, having the diameter at the mouth and bell end as secondary contributors? How does this affect the hole placement and the balance between otsu and kan?


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#2 2010-08-27 10:40:02

edosan
Edomologist
From: Salt Lake City
Registered: 2005-10-09
Posts: 2185

Re: What primarily determines large vs. small bore

Colyn Petersen wrote:

When designing a flute, what determines what is considered large vs. small bore? Can it be governed largely by the choke point, having the diameter at the mouth and bell end as secondary contributors? How does this affect the hole placement and the balance between otsu and kan?

Some considerations:

       http://www.navaching.com/shaku/bore.html


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It takes effort to attain nothingness.
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#3 2010-08-27 11:25:41

Toby
Shakuhachi Scientist
From: out somewhere circling the sun
Registered: 2008-03-15
Posts: 405

Re: What primarily determines large vs. small bore

Colyn Petersen wrote:

When designing a flute, what determines what is considered large vs. small bore? Can it be governed largely by the choke point, having the diameter at the mouth and bell end as secondary contributors? How does this affect the hole placement and the balance between otsu and kan?

I'm not in agreement with everything Nelson says, but much is true. Essentially, the bore size is determined by the utaguchi and upper-end diameter. A reverse-taper serves mostly to keep the pitch from dropping too much as the blowing pressure is lowered, and slightly stretches the mode relationships so that the upper modes (kan and dai-kan) do not go too flat as the player shortens the air jet in order to play the higher modes. An incorrect taper angle, i.e., a choke point too small (or too large) for the top diameter of the bore, can create a number of problems, especially with tuning, and variations in the taper along the bore can completely screw up the mode relationships for certain notes (depending on where the perturbation is located in the bore), creating out-of-tune, weak, or impossible notes in the kan and dai-kan.

The widening of the bore back out after the choke point actually isn't necessary acoustically. It was probably instituted in order that the root end did not have to be cut too short, as it slightly raises the modes of the lower notes and thus makes them play at a slightly higher pitch for the length. As you know, you have to be very careful with that, as an incorrect positive taper can really screw up the Ro.

Most global response, timbre and general intonational issue are determined in the top 1/4-1/3 of the bore. Once the finger holes start, you are getting into the area which determines intonation and general response of individual notes or small groups of notes.

Toby

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#4 2010-08-27 14:28:38

PSmith
Member
From: Vancouver, BC
Registered: 2008-09-08
Posts: 29

Re: What primarily determines large vs. small bore

Have you checked out Ken LaCosse and Brian Tairaku Ritchie's video on differences in bore width in their design of "Taimu" shakuhachi?

http://mujitsu.com/taimu.html

Scroll to the bottom of the page.

Here is the link on YouTube
http://www.youtube.com/watch?v=ij9jN9bq5mI

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#5 2010-08-27 20:30:27

Colyn Petersen
Member
From: Omaha, NE
Registered: 2009-11-20
Posts: 46
Website

Re: What primarily determines large vs. small bore

Interesting, choosing as low of an aspect ratio one could get away with has also swept the NAF world in recent years. Most particularly with the bass flutes, but some apply it to midrange as well.

PSmith wrote:

Have you checked out Ken LaCosse and Brian Tairaku Ritchie's video on differences in bore width in their design of "Taimu" shakuhachi?

http://mujitsu.com/taimu.html

Scroll to the bottom of the page.

Here is the link on YouTube
http://www.youtube.com/watch?v=ij9jN9bq5mI


Though images may appear on the surface of a mirror with clarity, they are neither in the mirror, nor sticking to its surface.

Dilgo Khyentse Rinpoche

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