Mujitsu and Tairaku's Shakuhachi BBQ

jaybeemusic · 2009-03-23 11:31:12

ok everyone....

here's a real head scratcher. I've been trying to wrap my mind around this one and i'm getting a headache.... LOL

If i build a shakuhachi out of PVC...it's just a straight tube, no taper. As i get into Kan the notes get progressively flatter. soooo conventional tuning wisdom states that the 1/4, 1/2 and 3/4 points of the bore are "hot spots" to look for. these spots lie ABOVE the hole (between utaguchi and hole)

generally you would add to these points to raise the pitch etc..... so technically the top half of the flute would be a bit smaller diameter...(at certain spots)

here's the problem...

The ideal bore of a shakuhachi is basically a REVERSE cone. Starting big at the utaguchi and getting smaller as we go down to the bottom, then flaring out again. which means that the bore has been modified (from perfectly straight) BELOW the holes towards the root end. which means that there must be something going on at the bottom part of the shakuhachi that is not covered by these 1/4,1/2 and 3/4 spots.

I just don't know what that is. and i hope to God that someone can shed some light on it..... please..

I know that the bore NEEDS to be tapered, i'm not disputing that fact, but i'm just trying to get a grip on a big missing piece of the puzzle.

thanks everyone

jacques

madoherty · 2009-03-23 12:06:27

I am not a pro but...
Sounds like you are tripping over the puzzle. The correct tuning otsu vs. kan, is achieved by the shape of the bore, and in particular the ratios set up by the correct bore taper. The "hot spots" may be manipulated, but the tapered bore is needed for the proper shakuhachi sound and tuning, under normal circumstances.

Best wishes.
Michael

jaybeemusic · 2009-03-23 12:30:01

I might be tripping but i don't think so.... Here are things i know

1. The shakuhachi bore MUST be tapered from top to bottom.
2. It must flare out on the end... (last 14% or so)
3. Hole placement matters most in Otsu.

If these things are done (correctly) you get a shakuhachi that is in tune. The confusing part is that most of the taper is BELOW the holes. (toward the root) And the higher you go in pitch, the more of the taper/adjustment is BELOW the holes.

Take "I" for example.....it's the highest hole, and on a PVC shakuhachi, it's the most out of tune between octaves. Most of the bore below it is tapered/adjusted but the top part (toward the utaguchi) is almost the same diameter the whole way up.

So that means that the taper below the hole is "lining-up" the 2nd octave. I'm not saying the bore above has no effect, but i'm sure that below has more to do with it.

i hope i'm making sense here because it's pretty confusing for me to try to explain what i'm talking about....thanks everyone for being patient.

jacques

Mujitsu · 2009-03-26 11:04:44

jaybeemusic wrote:
there must be something going on at the bottom part of the shakuhachi that is not covered by these 1/4,1/2 and 3/4 spots.

Jacques,

Yeah. Confusing stuff indeed! I like to think of the "hot spots" as constants and areas outside the hot spots as places that are relative to the overall bore profile.

I think Toby could offer an explanation which might be more useful for you.

jaybeemusic wrote:
1. The shakuhachi bore MUST be tapered from top to bottom.
2. It must flare out on the end... (last 14% or so)

A straight tube would make life easier for shakuhachi makers! But yes, a tapered bore can correct octave tuning issues.

A more subjective reason for a tapered bore is that it can offer slightly more resistance and greater depth of tone. This might translate to a shakuhachi that plays with mystery and elasticity.

A cylindrical bore shakuhachi offers a faster attack. This type of playability certainly has its place, but some feel it lets the cat out of the hat too soon!

purehappiness · 2009-03-26 11:40:30

I am totally new to this but I was just thinking the same thing about taper to a flute I was experimenting with. It basically has no real taper so I was thinking that is why RO is so weak as compared to the other notes(if I could find a nice tapered piece of bamboo I would have used it but my resources are extremely limited).

jaybeemusic · 2009-03-26 14:15:57

Hey people....

just so that everyone understands me properly i made a few pix...... here goes...

These are the tuning "hot spots" for each note and where they are.... notice that most of them are at the top end (utaguchi end) of the flute....

here's the problem...

MOST of the taper in the bore is at the bottom of the flute..... but it "somehow" fixes the tuning problems....

could someone explain to me what's going on? please.... or at least point me in the direction of the answer.... thanks...

i'm not trying to be a pest.... just trying to be the best "western" shakuhachi hack i can be.... lol

jacques

Last edited by jaybeemusic (2009-03-26 14:18:30)

madoherty · 2009-03-26 14:31:05

The bore acts as a complete organic unit, no matter what tone-holes are open. When you open to chi for example it is not the equivalent of cutting off the rest of the flute from that point down to the root... the rest of the flute is still attached and effects tuning and timbre....

A more experienced maker might be able to discuss the finer points of back-pressure, and bore profile, etc., and their effect on tuning to address your question more pointedly.

Last edited by madoherty (2009-04-04 09:57:44)

edosan · 2009-03-26 15:34:28

Here is a PDF from John Neptune which will either roil the waters or be of use, or both
(direct download link; 1.5MB):

http://img262.imageshack.us/img262/3058 … ngbore.pdf

dreamofnobody · 2009-03-26 15:54:50

Hi jaybeemusic.

There is two cones in the bore. First goes from utaguchi to the gorobushi point. Second cone goes from gorobushi to the foot. Most part of "hot spots" are in the first cone, in the upper part of the flute. It is the most significant part of shakuhachi. Second cone affects most on the Ro. You can affect the sound color and the pitch of Ro by opening bottom hole (so affecting the shape of the second cone).

That is my vision.

Did you read this?

http://navaching.com/shaku/jinashi.html
http://navaching.com/shaku/second.html

May be it can be some helpfull too.

And one thing about spot tuning that the best way to understand it is to go in the bore with the bead on the string and experiment. Use these graphs to understand the things what will be.

Last edited by dreamofnobody (2009-03-26 15:56:55)

jaybeemusic · 2009-03-26 18:00:56

Thanks edosan,

i've already read that and i'm still confused....

here's the problem, if i've got a shakuhachi with Kan flat relative to otsu.....(that's the most common problem for me) i'm gonna use the spot tuning method
and add some stuff to the 1/4 or 3/4 points and "hopefully" raise the Kan note. like this...

If i do that, i'm left with a bore that is backwards....(smaller at the utaguchi than the root) now i know that's not right. (i've tried it and it doesn't work)

sooooo....if adding stuff up here isn't right....what is the right answer?

If i'm going to taper the bore....there's gotta be some rhyme/reason for doing so and not just randomly adding stuff in there to make a "taper"

up to this point i haven't seen much info (and yes i've looked) on the bottom half of the shakuhachi.

any takers?

thanks a million everyone....

jacques

Last edited by jaybeemusic (2009-03-26 18:01:54)

radi0gnome · 2009-03-26 20:31:29

Jaybee, I know that baroque flutes have a similar reverse conical shape to the shakuhachi, so I started googling "baroque flute conical" and refined the search based on what I found. What I found was a bit too in depth for me to try to fully understand now, but I started interpreting from what I was reading that the column of air containing the standing wave does not stop dead at the first open hole but instead extends past the hole by some amount. Then I think "acoustic impedance" comes into play, the conical bore increases it. The details of this stuff is beyond me, but until someone can post something that more directly answers your question some googles on those search terms might help you some. As it is, from reading it I think I have as much of an understanding of what's going on as I personally need, but I could be completely off base.

DaveDew · 2009-03-27 01:46:46

Hi Jaques

I will assume that your PVC tibe is 20mm internal diameter and 545mm long
that said a standard 1.8 is 20mm at the utuguchi 17.5mm at the joint and 18mm at bottom and 14.5mm at approx 90 mm from the end of the flute

If we start with RO kan these dimensions represent one preasure node at the middle and two flow nodes at either end
by constricting the 20mm tube at the centre (preasure node) to 17.5mm RO Kan gets sharper in pictch this is then balanced out by constricting the base to 18mmwhich will bring the tuning back to nominal this is obviously a simplification that deals only with these points. In reality these nodes have length where the maximum impact of adding or subtracting material is right on the node diminishing as we move away with a neutral point halfway between flow and preasure nodes.

The preasure node at the centre is also close to a flow node of Ri
So if you Imagine that you have finished your flute and Ri is sharp, adding here would lower its pitch but raise the pitch of RO Kan
its also close to flow and preasure nodes of other notes, such as RO otsu. Something to be aware of is that preasure nodes become flow nodes and neutral points preasure nodes in the otsu register.

So now if we look only at the upper half of the flute and add material between 17.5mm at the middle and 20mm at the utuguchi we will add mostly to the preasure nodes of all Kan notes thus raising their pitch.

Now we can look at the lower half of the flute and add material between 17.5mm, 14.5mm and 18mm we will add mostly to the flow nodes of all kan notes thus lowering their pitch.

The overall effect should bring balance and minor adjustments can be made to improve the tone color

The area around the centre of the flute is also critical for performance this is of course relative to the overall dimensions but it is something to keep in mind when making your flutes.

my personal experiences vary but I have had unstable RO Kan such as Vibrato when this dimmension isn't right.

I have also seen many flutes vary from these dimensions but they are a good starting point.
Ken from Mujitsu shakuhachi has posted a link to these dimensions they are a great start.

Have fun and enjoy the journey

Dave

lossafunk · 2009-03-27 07:53:16

jaybeemusic wrote:
i'm gonna use the spot tuning method
and add some stuff to the 1/4 or 3/4 points and "hopefully" raise the Kan note.
jacques

for me I usually do the opposite. remove material at the critical points, raise the note. Add material at the critical points, lower the note. Also you may want to try tuning ro to it's octave before drilling other holes. That is to say, blow RO, then over blow RO. Tune the two to each other by opening or closing the end hole. It works for me get the the flute into tune more easily.

Todd

lossafunk · 2009-03-27 09:20:25

Bye the way, After I tune RO, I work from the blowing edge down: Hole 5 first then hole 4 etc. I also like to fine tune at the pressure and flow nodes directly after the finger holes.

_todd

DaveDew · 2009-03-31 19:02:29

Hi Jaques

My appologies I wrote

So now if we look only at the upper half of the flute and add material between 17.5mm at the middle and 20mm at the utuguchi we will add mostly to the preasure nodes of all Kan notes thus raising their pitch.

Now we can look at the lower half of the flute and add material between 17.5mm, 14.5mm and 18mm we will add mostly to the flow nodes of all kan notes thus lowering their pitch.

I actually got Kan and otsu the wrong way round mainly because I tune with a western tuner and change my music to western notaion sorry for the error.

so the text should have read

If we start with RO OTSU these dimensions represent one preasure node at the middle and two flow nodes at either end
by constricting the 20mm tube at the centre (preasure node) to 17.5mm RO OTSU gets sharper in pictch this is then balanced out by constricting the base to 18mmwhich will bring the tuning back to nominal this is obviously a simplification that deals only with these points. In reality these nodes have length where the maximum impact of adding or subtracting material is right on the node diminishing as we move away with a neutral point halfway between flow and preasure nodes.

The preasure node at the centre is also close to a flow node of Ri
So if you Imagine that you have finished your flute and Ri is sharp, adding here would lower its pitch but raise the pitch of RO Kan
its also close to flow and preasure nodes of other notes, such as RO KAN. Something to be aware of is that preasure nodes become flow nodes and neutral points preasure nodes in the KAN register.

So now if we look only at the upper half of the flute and add material between 17.5mm at the middle and 20mm at the utuguchi we will add mostly to the preasure nodes of all OTSU notes thus raising their pitch.

Now we can look at the lower half of the flute and add material between 17.5mm, 14.5mm and 18mm we will add mostly to the flow nodes of all OTSU notes thus lowering their pitch.

The overall effect should bring balance and minor adjustments can be made to improve the tone color

The area around the centre of the flute is also critical for performance this is of course relative to the overall dimensions but it is something to keep in mind when making your flutes.

my personal experiences vary but I have had unstable RO OTSU such as Vibrato when this dimmension isn't right.

I have also seen many flutes vary from these dimensions but they are a good starting point.
Ken from Mujitsu shakuhachi has posted a link to these dimensions they are a great start.

Have fun and enjoy the journey

Dave

Toby · 2009-04-03 11:40:30

jaybeemusic wrote:
I might be tripping but i don't think so.... Here are things i know

1. The shakuhachi bore MUST be tapered from top to bottom.
2. It must flare out on the end... (last 14% or so)
3. Hole placement matters most in Otsu.

If these things are done (correctly) you get a shakuhachi that is in tune. The confusing part is that most of the taper is BELOW the holes. (toward the root) And the higher you go in pitch, the more of the taper/adjustment is BELOW the holes.

Take "I" for example.....it's the highest hole, and on a PVC shakuhachi, it's the most out of tune between octaves. Most of the bore below it is tapered/adjusted but the top part (toward the utaguchi) is almost the same diameter the whole way up.

So that means that the taper below the hole is "lining-up" the 2nd octave. I'm not saying the bore above has no effect, but i'm sure that below has more to do with it.

i hope i'm making sense here because it's pretty confusing for me to try to explain what i'm talking about....thanks everyone for being patient.

jacques

A reverse-conical taper has the effect--relative to a cylindrical bore--of changing the impedance curve in a way which confers increased pitch stability with blowing pressure. However the taper is not really necessary to achieve true octaves, as long as the bore profile near the top is correct. It is entirely possible to make a shakuhachi with a simple cylindrical bore that plays in tune, although the hole placement would have to be adjusted and there would probably be some changes in the third octave.

Hole placement matters in all registers, because a correct bore profile will sound true octaves.

Toby

Toby · 2009-04-04 09:49:53

It is important to realize that there are two critical points for a given wave where tuning can be affected. Any standing wave in an air column has a point or points where there is a minimum of air movement but a maximum of pressure variation. This is called a node, or a pressure (or compression) node. Midway between nodes are antinodes, where the air displacement is at a maximum and the pressure variation at a minimum (also called displacement or velocity antinodes).

If the bore is restricted at a pressure node, the pitch of the sounding note is raised; if the bore is enlarged at that point the pitch is lowered. At antinodes the story is the opposite: restricting the bore at an antinode results in a lowering of pitch, whereas widening the bore at that point raises it.

The effect of any bore modification is at a maximum exactly at a node or antinode, and lessens the further one gets from one of those points.

Perhaps you can see where this is going. Since the position of nodes and antinodes change for each note, a bore modification intended to bring an errant note in tune can result in detuning a different note. And of course any note has not only the nodes and antinodes of the fundamental, but important nodes and antinodes of its major partials. It is very possible, for instance, that the node for the fundamental of one note is at the same position for an antinode of the first partial for another; so restricting the bore at the pressure point for the first note in order to raise the pitch will lower the pitch of the second note in the second octave. It is quite a complicated cocktail.

Toby

Last edited by Toby (2009-04-05 07:14:04)

Toby · 2009-04-04 10:02:07

jaybeemusic wrote:
Thanks edosan,

i've already read that and i'm still confused....

here's the problem, if i've got a shakuhachi with Kan flat relative to otsu.....(that's the most common problem for me) i'm gonna use the spot tuning method
and add some stuff to the 1/4 or 3/4 points and "hopefully" raise the Kan note. like this...

http://i302.photobucket.com/albums/nn81 … o-Spot.jpg

If i do that, i'm left with a bore that is backwards....(smaller at the utaguchi than the root) now i know that's not right. (i've tried it and it doesn't work)

sooooo....if adding stuff up here isn't right....what is the right answer?

If i'm going to taper the bore....there's gotta be some rhyme/reason for doing so and not just randomly adding stuff in there to make a "taper"

up to this point i haven't seen much info (and yes i've looked) on the bottom half of the shakuhachi.

any takers?

thanks a million everyone....

jacques

The most important thing is to maintain a constant angle in the bore! This is rule number one acoustically. Any time you change the cone semi-angle you shift the partials away from their correct integer ratios, which means that the second octave utilizing the first partial as the sounding frequency is not going to be a true octave. Eventually when you have things more or less in order you can do some local fiddling to fine tune things, but if you don't start with a constant cone angle down to the choke point (or pretty close: there are some desirable *small* variations) you are lost.

Toby

Mujitsu and Tairaku's Shakuhachi BBQ

#1 2009-03-23 11:31:12

Big Can of Worms.... (tuning)

#2 2009-03-23 12:06:27

Re: Big Can of Worms.... (tuning)

#3 2009-03-23 12:30:01

Re: Big Can of Worms.... (tuning)

#4 2009-03-26 11:04:44

Re: Big Can of Worms.... (tuning)

jaybeemusic wrote:

jaybeemusic wrote:

#5 2009-03-26 11:40:30

Re: Big Can of Worms.... (tuning)

#6 2009-03-26 14:15:57

Re: Big Can of Worms.... (tuning)

#7 2009-03-26 14:31:05

Re: Big Can of Worms.... (tuning)

#8 2009-03-26 15:34:28

Re: Big Can of Worms.... (tuning)

#9 2009-03-26 15:54:50

Re: Big Can of Worms.... (tuning)

#10 2009-03-26 18:00:56

Re: Big Can of Worms.... (tuning)

#11 2009-03-26 20:31:29

Re: Big Can of Worms.... (tuning)

#12 2009-03-27 01:46:46

Re: Big Can of Worms.... (tuning)

#13 2009-03-27 07:53:16

Re: Big Can of Worms.... (tuning)

jaybeemusic wrote:

#14 2009-03-27 09:20:25

Re: Big Can of Worms.... (tuning)

#15 2009-03-31 19:02:29

Re: Big Can of Worms.... (tuning)

#16 2009-04-03 11:40:30

Re: Big Can of Worms.... (tuning)

jaybeemusic wrote:

#17 2009-04-04 09:49:53

Re: Big Can of Worms.... (tuning)

#18 2009-04-04 10:02:07

Re: Big Can of Worms.... (tuning)

jaybeemusic wrote:

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