Does windway size affect tone?

[Thomas-Hastay]

To answer your original questions..."Can anyone help? how do (voicing) dimensions effect tone."

The voicing, including the parts...the windway, the emboucure hole(window),the labium ramp and the "ears"(sides) are the "sound generation device" of the duct flute. Every aspect of the voicing can change the tone or sound generation. Here are some "basics".

The Windway: Directs the airstream across the window to strike the labium ramp edge.(75% above the edge,25%below). The size of the windway opening controls the airstream velocity which controls pitch(frequency of oscillations). The "lips" of the windway control the shape of the airstream>(Example:rounded lips = fan shape or sharp lips = bar shape)

Labium Ramp Angle: Controls pitch bending ability and register shift respose. (Example:A shallow angle allows greater pitch bending with small changes in breath pressure and faster register shifts {Tabor Pipe}. A steep angle gives stable pitch with small changes in breath pressure and slower register shifts {Recorder}.

Labium Ramp edge: A sharp edge requires a higher velocity airstream to oscillate, while a rounded edge requires a lower velocity airstream. The process is called "Generating a Von Karman Vortex Street".

http://en.wikipedia.org/wiki/Von_Karman_vortex_street

[highwood]

I am using calculations that I derived from scratch - that is I use the equations that Pete Kosels flutomat is derived from (which have been kicking around for a long time - 1930s I think), but do not make some of the trig approximations before solving. The errors from the approximation give holes that are tuned flat - and this is a good thing, at least better than being sharp, since one can easily drill out a hole but it is harder to make it smaller.

For what is worth my spreadsheet gives
394.17
345.80
291.06
219.77
195.62
121.46
with all 12mm holes, measured from the bottom - note that most of my holes are about 4 mm further up the instrument, and that my 4th hole is quite a bit further up.
Note:
1/ I would not make a whistle with the fourth hole as big as all the rest.
2/ I think these holes are a touch to small and would guess this instrument would have trouble playing the octave 000 000 (or G#)

Bill

[highwood]

And for you both: What is the best way to express window distance to the labium, to the fipple block, or to the centre?

I'm not quite sure what this question is asking - but answering anyway!

The window calculation is problematic since it is not a round hole and the wall thickness varies, so even if you assume that a hole calculation is accurate (which it is not several assumptions/approximations are made which of course is par for the course in modeling something) it is hard to calculate this accurately - I even have a fudge factor in my spreadsheet to change as needed for this.

Anyway the measurement as for other holes is to the center of the hole, not to the fipple block (which may not be even with the windway exit - such as in a Generation Whistle) or to the labium. Of course it is simple math to calculate these distances and I find it easier to have a measurement to the labium for construction purposes.

Of course this does not matter much as long as you are close and making a tunable whistle - if I'm not sure about the lengths I just leave a little extra length on the top of the body (the holes are drilled measured from the bell) and then trim off the top of the body or bottom of the head as needed to get the whistle in tune (the details of this will depend on your tuning slide design).

[highwood]

One thought to share:
The first two whistles I made were pretty good. But then:

The more whistles I made the more I realized I knew less, until it started to make sense and I thought I knew more, about which time a whistle came along that did not work or worked and should not have and I knew I knew less until I made some sense of it and I knew a little more, maybe, and at some point I knew that I could make a whistle head that worked well but I also know that making a small change might completely break the balance. And now I'm working on a almost completely different design!

make sense?

[DrPhill]

Some helpful stuff there, thanks Highwood.

I can empathise with your last point, if, as I think, you are saying 'the more I learn, the less I know'. That is how life seems to me. Like walking up a hill - the brow is right in front of you. Just a couple of steps. Except when you get there you realise that what you saw was not the summit. Or if it was, then there is a bigger summit after. (Now, why do I always visualise life as an uphill walk?)

Making my own whistle has added some to my understanding and appreciation of my bought whistles. Its easy for me to take such for granted - 'oh the cross fingered Cnat is off', 'the bell note breaks too easily', 'the high a and b are too shrill'. Then I play my home made one, and realise just what fine whistles the others actually are..... And then remember that these are largely hand made, reliably, repeatedly, and affordabley. The makers have my admiration.

[DrPhill]

My own changes to bring the calculations more in line with what I was observing building flutes and whistles are

1. a change to the bottom end correction in function C_end().
I use
return 0.5*Bore;
but sometimes I adjust the factor a bit.

2. a change to the embouchure correction (window correction for a whistle), to get a more accurate total length. For whistle design I use in function C_emb():
return 2.5*(Bore/2)*(Bore/2)/Math.sqrt(Demb1*Demb2);
Demb1 and Demb2 are window length and width. This is not too bad, but window wall height plays also an important role, so overall the total length from foot end to window block is not totally accurate, but better.

Would you like a 'HB modified flutomat' calculation in TWJCalc?

I will look in to generic ways to pass 'finagle factors' into the algorithm.

[DrPhill]

I have just had the time to fully contemplate your helpful points Thomas. Thank you.

Labium Ramp Angle: Controls pitch bending ability and register shift respose. (Example:A shallow angle allows greater pitch bending with small changes in breath pressure and faster register shifts {Tabor Pipe}. A steep angle gives stable pitch with small changes in breath pressure and slower register shifts {Recorder}.

What is the 'normal' range of a whistle Labium Ramp angle? I like the idea of more stable pitch, and I have been tending to very shallow angles. So steepening the angle of the labium ramp seems the way to go for my next whistle head, but I do not want to make a recorder.......

Does the width of the window/windway have effects other than 'back pressure? I am tempted to increase back pressure by reducing the windway from 15 to 10 mm. The embouchure hole width will be similarly reduced.

[highwood]

All other things being equal (which of course won't be true!) a narrower windway will take less air, and be quieter, and the pitch will be flatter. Tone - I would be guessing so I won't, I have not played with window width very much. Just my 2 cents.

[hans]

Would you like a 'HB modified flutomat' calculation in TWJCalc?

Not for my sake please! I suggest you try and find the formulas which best model whistles. And that may be a tall order! But what is the point in offering all kinds of algorithms for the same purpose? Surely one will be closer to reality than another. Unless they vary for the circumstances. I see a long road of research ahead!

[DrPhill]

[quote="hans" I suggest you try and find the formulas which best model whistles. And that may be a tall order! But what is the point in offering all kinds of algorithms for the same purpose? Surely one will be closer to reality than another. Unless they vary for the circumstances. I see a long road of research ahead![/quote]
I do not have the skills or the tools to make whistles accurately enough to test for fine differences. I do not have the tools or the ear training to measure the differences between the whistles. Nor do I understand the physics of whistles well enough to raise hypotheses to test. But apart from that...........

Some of these shortcomings could be rectified, but, seriously speaking, the task you suggest is probably beyond me.

My target was to make a playable bass A, and with the help of many here I am getting close. I admit this makes me a consumer of knowledge that others have gleaned, but I dont think I can pay back in the same coin.

TWJCalc was a spin-off from my learning process, and if it can help somebody else that would be very pleasing. For those whistle researchers who can write in Java it could provide a framework for developing their own algorithms, maybe even for sharing and comparing their algorithms with others should they wish. I am happy to develop the program in response to the users needs, and provide support and help for those using it, but I don't think I am going to be able to do meaningful whistle research.

[AvienMael]

And for you both: What is the best way to express window distance to the labium, to the fipple block, or to the centre?

I'm not quite sure what this question is asking - but answering anyway!

The window calculation is problematic since it is not a round hole and the wall thickness varies, so even if you assume that a hole calculation is accurate (which it is not several assumptions/approximations are made which of course is par for the course in modeling something) it is hard to calculate this accurately - I even have a fudge factor in my spreadsheet to change as needed for this.

Anyway the measurement as for other holes is to the center of the hole, not to the fipple block (which may not be even with the windway exit - such as in a Generation Whistle) or to the labium. Of course it is simple math to calculate these distances and I find it easier to have a measurement to the labium for construction purposes.

Of course this does not matter much as long as you are close and making a tunable whistle - if I'm not sure about the lengths I just leave a little extra length on the top of the body (the holes are drilled measured from the bell) and then trim off the top of the body or bottom of the head as needed to get the whistle in tune (the details of this will depend on your tuning slide design).

Actually, most of this is totally irrelevant, IMO. It is the distance between the blown edge and the bell end that gives you a correctly tuned bell note. Trying to guess exactly where that blown edge will end up (by finding center of hole) when you have actually achieved it is a little like shooting into darkness. If your whistle is to be of a non-tunable design, then once your mouthpiece is finished enough to generate sound (don't completely finish it, you may want to disassemble and adjust something when voicing.), you simply warm the entire piece and then cut the whistle to length using a tuner. Your tone holes are then laid out from the cut edge. To carry this a step further (literally), and in addressing tunable whistles, my tunable whistles each begin their lives as a non-tunable whistle, and is then made tunable by cutting and adding an appropriate sleeve.


As to using Pete Kosel's java calculator, embouchre diameter is important. On a high whistle, you will want to use .25" in your calculation, rather than .500". On a lower whistle (say between middle C and low D), using .3750" may work better depending on your ID. Next thing I do when using Pete's calculator is to drill all of the tone holes under-size. That is, I centerpunch each hole, then start drilling small and step each hole up slowly. When they are all within .0625" of the diameters given by the calculator, I stop drilling and start playing, and voice the whistle for tuning from there, focusing mostly on the upper octave.

This is a simple, but effective and reliable method that I have been using for years now. Probably the best advice for anyone who is serious about making whistles is to keep notes on each one. Over time you will be able to develop a "formula" for each one that produces a good playing and sounding whistle consistently.

[Thomas-Hastay]

To compensate for the Trapezoidal shape of the voicing window you must "average" the diameter before you "plug them in" to Flutomat (or other) calculators.
(La + Wa/2) + (Lb + Wb/2) /2 = Davg
"The average diameter at the bottom of the square window plus the average diameter of the top of the square window, divided by 2 equals Davg " or the Equivalent of a round embouchure. QED

Recorders use the tapered angle of the bore to "shift" the nodes/anti-nodes and "tune" the first 2 registers. The drawback to this is a limited register range (2.5 octaves). Most pennywhistles keep their range and compensate for flat pitch in the upper registers by increasing the windway velocity (more breath pressure) to sharpen/compensate for this "phase shift flattening effect" and maintain correct pitch. This requires the player to have a good "ear" for pitch though. Some whistle makers (Generation) use a tuned resonator cavity, like a flute, to tune interregister harmonics.

[highwood]

Actually, most of this is totally irrelevant, IMO. It is the distance between the blown edge and the bell end that gives you a correctly tuned bell note

If you want to calculate the length of the whistle it is the distance to the center of the hole or window that is used in the calculations.

It is the distance between the blown edge and the bell end,
and ...
the window size
wall thickness
bore id
perturbations in the bore (ie covered holes, tuning slides)
air temp
humidity
phase of the moon (not really)
the way the player plays (really)
and ... I'm sure I missed something ... actually I know I have not included some things, but you get my drift ...
that gives you a correctly tuned bell note.

And then you have to worry whether the octave 'bell note' is in tune - probably will not be ...

[Thomas-Hastay]

Yes Highwood, BUT...there is a "false bore extension" to the aircolumn at the voicing which must be compensated for. This aircolum extention at the voicing is critical to Keynote pitch and sets the location of anti-nodes for tonehole placement. Flatness of pitch multiplies with successive registers.

(D/Eavg)squared X ({2/3} X {E + T} = False Bore Extention.

D = Bore diameter at the voicing
Eavg = The averaged Emboucure/Voicing Diameter
T = The Thickness/Depth of the Embouchure/Voicing

[DrPhill]

To compensate for the Trapezoidal shape of the voicing window you must "average" the diameter before you "plug them in" to Flutomat (or other) calculators.
(La + Wa/2) + (Lb + Wb/2) /2 = Davg
"The average diameter at the bottom of the square window plus the average diameter of the top of the square window, divided by 2 equals Davg " or the Equivalent of a round embouchure. QED.

Hmmmmm, I was wondering whether the walls of the voicing window (i.e. the cut edges of the whistle tube) should be cut on a line pointing at the centre of the tube (a radius as it were) giving a hole smaller on the inside of the tube, or cut vertically down giving a constant width hole. Perhaps this choice also matters......