Mujitsu and Tairaku's Shakuhachi BBQ

Benjamin · 2009-07-22 06:53:52

I have been working on a flute for some time now and have an interesting query. The flute in question is a 1.65 Jinashi (or will be) with a significantly big bore for its size and good thick walls. I got this piece of bamboo back when I was in high school 4 years ago, and when I went to open the bell end I first drilled a hole that is approximately 14 mm. Then I took a rather large domed stone bit and was going to open it up all the way but instead stopped with about 15mm of penetration and a new bottom opening of 24 mm to create a convex recess in the bottom of the bamboo. (picture links below)

http://photos-g.ak.fbcdn.net/photos-ak- … 4_6150.jpg
http://photos-c.ak.fbcdn.net/photos-ak- … 4_3220.jpg
http://photos-d.ak.fbcdn.net/photos-ak- … 1_7672.jpg

My question is: In theory what type of changes in pitch would this have for Ro as well as the over all tuning of the flute? Or effect on acoustics? Its over all length is 50.2 cm. Now that the opening has been brought back up by 1.5 cm the bore length is 48.7cm or there abouts which to my recollection is pretty darn close to 1.6. Ro is very easy and only a couple cents flat of E. Is there any reason to think that this type of opening would have the same effect as the common concave flared out end? My intuitive side says yes but I thought that I would post due to the fact that I don't think this has ever been addressed before, or I haven't seen any flutes with this type of opening. If it does turn out to be a problem I have made a deer bone plug that I'll inlay and re-drill to more exact specifications.

http://photos-f.ak.fbcdn.net/photos-ak- … 3_5859.jpg

Was just wondering if others would like to know or think about the possibilities of this type of end on a flute.

Mujitsu · 2009-07-22 12:35:10

Benjamin wrote:
My question is: In theory what type of changes in pitch would this have for Ro as well as the over all tuning of the flute? Or effect on acoustics?

Benjamin,

If I understand correctly it seems the theoretical length of the flute is being shortened? Is that the idea?

My guess is that it would raise RO more than a concave flared end. Perhaps similar to drilling a small hole near the end of the flute. So, it could (theoretically) help if you are trying to sharpen the tonic directly on pitch or there are hole/node placement problems.

As you know, the bottom 9cm or so of the bore is a very touchy area for tone. Anything you do there will influence the tone in some way. So, you'd need to experiment to be sure that you are not compromising tone quality for pitch flexibility. It's always a balancing act!

In the end, whatever works!

Toby · 2009-07-25 05:03:34

The pix are not that clear, and I do not really understand what you did. A convex recess? Do you mean that the bore widens near the end and then gets smaller again at the exit hole?

What I see is that there is a large stepwise enlargement of the bore, which has a relatively large flare angle. Is that correct?

Acoustically that is not a good idea. Any stepwise discontinuities of the bore create turbulence at the step edge. This will rob the notes of power at loud dynamics among other things. Yes, it will raise the pitch of ro somewhat. Generally a flared bell acts as a high-pass filter, although for technical reasons a flute doesn't really need one. My suggestion is to make a smooth flare to the final exit diameter, whatever that is. If you find that the exit hole at the bell is too large it is possible to make a bamboo sleeve insert to narrow it.

Toby

Mujitsu and Tairaku's Shakuhachi BBQ

#1 2009-07-22 06:53:52

Convex Bell

#2 2009-07-22 12:35:10

Re: Convex Bell

Benjamin wrote:

#3 2009-07-25 05:03:34

Re: Convex Bell

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