Mujitsu and Tairaku's Shakuhachi BBQ

World Shakuhachi Discussion / Go to Live Shakuhachi Chat

You are not logged in.


Tube of delight!

  • Index
  •  » Flutemaking
  •  » resonance in some flute moving from kan Hi to dai Kan i

#1 2011-01-18 16:21:03

garyc
Member
Registered: 2010-09-03
Posts: 4

resonance in some flute moving from kan Hi to dai Kan i

I have made several flutes, some ( various lengths and bore sizes ) which seem to jump to a resonance when I play upper with 3 and 4 open ( kan Hi ?) then 3,4, 5 open  ( dai kan ? ), this is a common transistion in honkyoku I play.  I thought it might be larger bores reaching the upper limit of it range, but it has come up in a particularly nice peice of bamboo with a aspect ratio length/width that look's high. I've tried inserting objects into the upper end of the bore, changing hole sizes to vent more or less, to no effect! Once the flute hits the resonance finger holes have no real impact.  Does any know what causes this and if there's a workable cure for it?

Offline

 

#2 2011-01-18 19:27:48

Karmajampa
Member
From: Aotearoa (NZ)
Registered: 2006-02-12
Posts: 574
Website

Re: resonance in some flute moving from kan Hi to dai Kan i

What pitch/relative pitch is it resonating at ?
How hard/soft are you blowing ?
Does half-holing or meri affect this occurance ?
How deep/shallow is the curve of your utaguchi ?

Kel.


Kia Kaha !

Offline

 

#3 2011-01-19 11:21:22

garyc
Member
Registered: 2010-09-03
Posts: 4

Re: resonance in some flute moving from kan Hi to dai Kan i

Kel, thanks for responding

All good questions.
Let me see if I can answer them for one  flute, but this happens on a few other flutes as well.

Pitch -  one to one and a half notes higher than it should be for the fingering of 345 open and playing Kan. Clearly jumps otsu transision is in good tune.
blowing - pretty tight air stream, I either get no note or this higher unwanted pitch, no control of it once it jumps
half holing/meri - no shading or covering of 3,4,5 seems to help, sometimes very meri light but focus air will get a weak correct pitch note. 
depth of utaguchi - 3-4mm on this flute, generally I keep them around 2-4 mm

As I indicated above this has happen to me on a few other flutes, one that has the same problem but less desireble bamboo was the subject of an experiment last night,  on most of my flutes hole 3 is small to allow the 3-4 spacing to be more comfortable , if I opened hole three up to vent more it seemed to improve, before I persue this on the better flute was hoping those of you with more experience had seen this problem and understood more than I.

I really don't want to give up on this flute.

Thanks again

Offline

 

#4 2011-01-19 14:49:31

Karmajampa
Member
From: Aotearoa (NZ)
Registered: 2006-02-12
Posts: 574
Website

Re: resonance in some flute moving from kan Hi to dai Kan i

Have you cleaned out all of the septum at the blowing end, or do you leave some in ?
Do you insetrt an utaguchi  or use the bamboo ?
Is the slope of your edge grater or less than 20 degrees and your curve shape, what is that like ?
I  also suspect your embouchure, what happens if you change from an 'Ooooo' to an 'Eeee' or the reverse ?

You won't be throwing this flute away, sometimes it takes months to resolve such a challenge.

Kel.


Kia Kaha !

Offline

 

#5 2011-01-19 16:20:50

Karmajampa
Member
From: Aotearoa (NZ)
Registered: 2006-02-12
Posts: 574
Website

Re: resonance in some flute moving from kan Hi to dai Kan i

Can you record an mp3 you can post ?

K.


Kia Kaha !

Offline

 

#6 2011-01-19 17:59:44

Tairaku 太楽
Administrator/Performer
From: Tasmania
Registered: 2005-10-07
Posts: 3225
Website

Re: resonance in some flute moving from kan Hi to dai Kan i

Great avatar!


'Progress means simplifying, not complicating' : Bruno Munari

http://www.myspace.com/tairakubrianritchie

Offline

 

#7 2011-01-19 21:41:23

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

Re: resonance in some flute moving from kan Hi to dai Kan i

garyc wrote:

I have made several flutes, some ( various lengths and bore sizes ) which seem to jump to a resonance when I play upper with 3 and 4 open ( kan Hi ?) then 3,4, 5 open  ( dai kan ? ), this is a common transistion in honkyoku I play.  I thought it might be larger bores reaching the upper limit of it range, but it has come up in a particularly nice peice of bamboo with a aspect ratio length/width that look's high. I've tried inserting objects into the upper end of the bore, changing hole sizes to vent more or less, to no effect! Once the flute hits the resonance finger holes have no real impact.  Does any know what causes this and if there's a workable cure for it?

Just to be clear: every note is a resonance. In your case the correct resonance is weak for one reason or another, and so the flute forms an oscillation at the point of a stronger resonance, which is apparently not the one you want.

Since this is the dai-kan, most probably the problem is caused by incorrect bore geometry, which throws off the upper harmonics. Each tube length has specific nodal points along the bore, at which altering the local diameter will affect the harmonics of the note in question. So it is not enough to just blindly poke things inside the bore; it is necessary to adjust the bore in the right places in the right amounts.

Offline

 

#8 2011-01-20 10:37:02

Yungflutes
Flutemaker/Performer
From: New York City
Registered: 2005-10-08
Posts: 1061
Website

Re: resonance in some flute moving from kan Hi to dai Kan i

Toby wrote:

garyc wrote:

I have made several flutes, some ( various lengths and bore sizes ) which seem to jump to a resonance when I play upper with 3 and 4 open ( kan Hi ?) then 3,4, 5 open  ( dai kan ? ), this is a common transistion in honkyoku I play.  I thought it might be larger bores reaching the upper limit of it range, but it has come up in a particularly nice piece of bamboo with a aspect ratio length/width that look's high. I've tried inserting objects into the upper end of the bore, changing hole sizes to vent more or less, to no effect! Once the flute hits the resonance finger holes have no real impact.  Does any know what causes this and if there's a workable cure for it?

Just to be clear: every note is a resonance. In your case the correct resonance is weak for one reason or another, and so the flute forms an oscillation at the point of a stronger resonance, which is apparently not the one you want.

Since this is the dai-kan, most probably the problem is caused by incorrect bore geometry, which throws off the upper harmonics. Each tube length has specific nodal points along the bore, at which altering the local diameter will affect the harmonics of the note in question. So it is not enough to just blindly poke things inside the bore; it is necessary to adjust the bore in the right places in the right amounts.

Hi garyc, have you read John Neptune's piece - An Interesting Bore?
http://www.pacificsites.com/~jneptune/

It's a great introduction on how a flute works. As Toby mentioned, you must be able to identify the different resonance spots that can affect one particular note.

If your aspect ratio is not ideal to start with, applying the theory of Spot Tuning will be difficult. If you are using a well-tapered root end bamboo, it could be that the bottom of the bore is too narrow. Or if the bore is cylindrical, it could be the opposite. (Actually it could be anything). But, all things being equal, you can try dropping a Tuning Bead around holes #3, #4 and #5. Add Ji where the note reacts better and remove bamboo where it gets worse. Or, it could be that you just need to undercut the #5 and/or #4 and #3.  Go no Hi is sometimes an issue even on some good Jiari flutes. An experienced player would play them it by opening #1 or #2 to some degree.

May I suggest doing a test? Make another flute with an aspect ratio as close as possible to the best flute you've made so far.  But on the test,  drill holes #4 and #5 7mm- 10mm lower than on the first flute. Make them bigger and undercut. I'm sure this test will tell you something.

Spot Tuning to makers is similar to color theory for painters. A painter must understand how mixing colors makes new colors. For example, mixing red and blue makes purple. Of course it gets quite complex as one will end up with different purples depending on the balance of red and blue. This is where a very important part of understanding color theory rests - it's relationship to light and background. A practiced artist will have in the studio a consistent light source (for the maker- proper technique of a particular style of music) and a clean white palette (proper aspect ratio).
Hope this helps,
- Perry


"A hot dog is not an animal." - Jet Yung

My Blog/Website on the art of shakuhachi...and parenting.
How to make an Urban Shakuhachi (PVC)

Offline

 

#9 2011-01-21 00:52:42

garyc
Member
Registered: 2010-09-03
Posts: 4

Re: resonance in some flute moving from kan Hi to dai Kan i

Thanks for the feedback,  sorry for the delay in responding to everyone, plumbing problems at my house took priority.

Bore info:
Root end culm but not madake, nice roots, dense bamboo, one of those that just feels right in the hands, which is why I do not give up.
wall thickness at hole 4  = 6mm  at hole 1 = 9mm
Dia below Utaguchi = 21mm
Dia at narrow point  = 16mm but this is within 50-60 mm of end ( possibly a problem? )
Length = 575mm  ( aspect is 27.4  is this a problem for 2+ octives?)
Utaguchi width = 14mm
Utaguchi depth = 3 mm
Utaguchi angle ~ 30 degrees
Holes 1,2,4 = 11.0 mm
Hole  3,5  = 9.5
Ro = C ~ 10% Flat

Kel:
utaguchi = is bamboo at this point and around 30 degrees, I can add kinko type inserts but usually I do this when I in the finishing stages and playing with the tuning.
OOO and eee  = does change this jump but is an interesting tonely impacts on other notes
mp3 upload = not sure how yet.

Toby:
I understand your points on resonance, my use of the term was not precise, but your right the unwanted resonance is the same as Nishi go no Ha  ( 2,4,and 5 open playing Kan ) but I'm fingering go no hi ( 3,4,5 open playing kan) .  Just need to try some of the suggestions hope I can get controllable go no hi.

Perry:
Thanks for the link, I have read John Neptune's peice, very helpful. I understand there are key pressure and flow points along the bore relating to 1/4 and 1/2 of the effective length of the note, what I hadn't known was that it was for a particular bore shape as you point out. I have to think about this more.

I haven't been able to get a handle on spot tuning, but would like to develope this skill but still build mostly Jinashi flutes.
I've tried attaching a large ( 7-8 mm) glass bead on a thread and look for it to change tuning, (is this what you mean by Tuning Bead?)  Probubly due to my limited skills in maintaining a consitent note pitch I haven't gotten consistent much effect + or - , "lack of proper technique". 

I also work with a wide variety and bamboo types and sizes, whatever I could get my hands on, plus I liked the different tonal qualities each piece of bamboo presents, but alais, I also want to play in tune and over the full range of notes needed for honkyoku, maybe it will require a more discplined approach , a more consistent palette.

Also I will try and work on my technique ( slightly opening 1 and 2 ) on one of my more well behaved flutes.

Next course of action , I try some of the experiments suggested, I think I will try lowering and opening hole 3,  Perry suggested something along thoses lines and this seemed to have a postive effect on another flute with a similar problem. Also will begin under cut on upper holes  too see if this affects the problem.

Avatar : thanks Tairaku, 160x160 pixels not alot to work with.


Thanks again for your help.

- Gary

Offline

 

#10 2011-01-21 01:58:32

Karmajampa
Member
From: Aotearoa (NZ)
Registered: 2006-02-12
Posts: 574
Website

Re: resonance in some flute moving from kan Hi to dai Kan i

Are you saying it is playing C or C# ?
575mm would be C#, if you are getting C then you would be playing too meri/flat.
Is a line drawn from the low point of your utaguchi curve to the low point of your chin rest perpendicular to the length of the flute ?
What is the diameter of the end hole ?
Have you bevelled any holes ? I would not bevel too quickly as it can alter pitch and volume as well as smooth the transition between note vibrations.
Only other thing that stands out a little is the angle of the utaguchi, but does not seem extreme, may be a bit steep. I also undercut or round out the undersides of the curve to widen it without deepening it.
no other measurement looks unusual to me.

K.

p.s. it sounds like a fairly chunky root end, deep chimney, I would be tempted to bevel, what is the relative volume like ?

Last edited by Karmajampa (2011-01-21 02:03:59)


Kia Kaha !

Offline

 

#11 2011-01-24 10:33:44

garyc
Member
Registered: 2010-09-03
Posts: 4

Re: resonance in some flute moving from kan Hi to dai Kan i

The combination of many things, including lowering and opening #3 and opening hole #2 when playing brings this flute's Go no Hi under control. With Perry suggestions on the fingering and after looking through the forum  dai kan can be flute by flute on Ji nashi flutes so maybe this is how it is.  After building another flute and pushing #3 higher and smaller as I did on the flute in question it also show some issues with Go no Hi stability, I guess hundreds of years of tradition behind hole placement is not to be changed with out risk and implications....   Futher tuning  and balancing will be needed.

On the surface elegantly simple flute design, below the surface, a complexity delicate balance of factors, and a constant source of frustration and joy. My respect for the master makers ancient and current grows.

Thanks for the suggestion folks.

Offline

 
  • Index
  •  » Flutemaking
  •  » resonance in some flute moving from kan Hi to dai Kan i

Board footer

Powered by PunBB
© Copyright 2002–2005 Rickard Andersson

Google