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#1 2006-03-29 17:28:22

dstone
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From: Vancouver, Canada
Registered: 2006-01-11
Posts: 552
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Wide-bore deviations from "standard" hole locations/sizes?

Hi all.  Beginner bamboo cutter here, trying my hand again.  I'm going to ramble on a bit here, so I hope nobody minds me using this forum as a place to think out loud!

Using my other flutes and the Zink and LaCosse references as guidelines, a starting point for placement (% from top) and diameter would seem to be approximately 41%/48%/58%/68%/78% with 11 mm holes except for a slightly smaller chi hole.

But I'm experimenting on a 966 mm flute (possibly 3.2-ish) with a bore that ranges from 36 mm down to 34.5 mm, so I suspect an adjustment needs to happen because the bore is wider than would normally be found on a flute of this length (I think).  The utaguchi is roughly cut and the nodes have been opened by maybe only 10 mm or so.  (It's currently blowing a fundamental tone of 148 Hz.)

Some references suggest that this flute would have a longer effective "acoustic length" (i.e. virtual length that extends beyond the physical bottom end) due to the disproportionately larger bore.

So does treating the flute as a slightly longer than it appears to be seem like the right approach?  If so, would the following two approaches seem reasonable and somewhat equivalent?
1. Using the "standard" position/size suggestion above but treat the flute like there was more length at the end -- effectively shifting all the holes farther down the flute, away from the mouthpiece.
2. Keep the holes in the same place as prescribed for a normal bore, but make the holes smaller.

I should mention that I'm making this flute in the hocchiku mindset, so if I have a goal, it's only to have the flute playable in tune with itself. 

Thoughts?

-Darren.

Last edited by dstone (2006-03-29 17:30:24)


When it is rainy, I am in the rain. When it is windy, I am in the wind.  - Mitsuo Aida

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#2 2006-03-29 21:00:18

kyoreiflutes
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From: Seattle, WA
Registered: 2005-10-27
Posts: 364
Website

Re: Wide-bore deviations from "standard" hole locations/sizes?

Wow, I never thought about the bore dia. making that big a difference, but I suppose it could. I'm about to make some Hocchiku, too, so this would be very helpful info to have.

-E


"The Universe does not play favorites, and is not fair by its very Nature; Humans, however, are uniquely capable of making the world they live in fair to all."    - D.E. Lloyd

"Any man's death diminishes me, because I am involved in mankind, and therefore never send to know for whom the bells tolls; it tolls for thee."    -John Donne

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#3 2006-03-29 21:43:51

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

Re: Wide-bore deviations from "standard" hole locations/sizes?

Before you do, go read everything here:

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

It's a pretty thorough treatise on bore variables, acoustics of resonating tubes, and shakuhachi tuning. Not what you'd call 'traditional', but much to be learnt there.

eB


Zen is not easy.
It takes effort to attain nothingness.
And then what do you have?
Bupkes.

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#4 2006-03-30 11:38:03

dstone
Member
From: Vancouver, Canada
Registered: 2006-01-11
Posts: 552
Website

Re: Wide-bore deviations from "standard" hole locations/sizes?

Thanks, Ed.  Yes, that's the Nelson Zink reference I mentioned.  Gem of a site!  I think I understand some of the principles there, but his chokan (big flute) page suggest at least one really unintuitive thing to me.

What he seems to claim is that, for a long flute, as long as hole 5 is 44% down from the top, then the total length of the span of the holes 5 thru 1 doesn't matter (i.e. pick a comfortable span) and all that matters is that they're spaced out in the same proportions as a shorter reference flute with that (shorter) span.  Of course, the hole sizes will vary, but still, I find that remarkably flexible.  I'm amazed and skeptical... thus, my question....  wink

I understand that hole size can compensate quite a bit, but this is the principle I'm surprised by:
http://www.navaching.com/shaku/shaku.gifs/chokan1.gif
(red flute is a shorter reference flute with a comfortable span and blue flute is the big flute that receives the shorter-than-usual spacing of holes)


When it is rainy, I am in the rain. When it is windy, I am in the wind.  - Mitsuo Aida

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#5 2006-03-30 11:47:03

Mujitsu
Administrator/Flutemaker
From: San Francisco
Registered: 2005-10-05
Posts: 885
Website

Re: Wide-bore deviations from "standard" hole locations/sizes?

dstone wrote:

Some references suggest that this flute would have a longer effective "acoustic length" (i.e. virtual length that extends beyond the physical bottom end) due to the disproportionately larger bore.

So does treating the flute as a slightly longer than it appears to be seem like the right approach?  If so, would the following two approaches seem reasonable and somewhat equivalent?
1. Using the "standard" position/size suggestion above but treat the flute like there was more length at the end -- effectively shifting all the holes farther down the flute, away from the mouthpiece.
2. Keep the holes in the same place as prescribed for a normal bore, but make the holes smaller.

I should mention that I'm making this flute in the hocchiku mindset, so if I have a goal, it's only to have the flute playable in tune with itself. 

Thoughts?

-Darren.

I think you are right on it Darren. When there is a lot of bore volume compared to length, the fundamental pitch is lower. To compensate, just nudge the holes a bit south. Smaller holes in the 'original' location will theoretically do the same in terms of pitch. You can base that decision on the desired tone color, volume and playability.

Ken

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