Making my own A# (B flat): question about diameter

[FrankFlute]

I want to make my own A# flute, in teak or purperheart. I have these at home.
But I don't know what bore-diameter to choose.

Native american A# would be 20 mm (3/4).
But that seems rather wide in my opinion. I know smaller bores make overblowing somewhat easier.
So would 16 mm be a good diameter?

What is the bore from your flute?

[Nanohedron]

Are you talking about flutes or whistles, here?

[Tunborough]

For whistles, the latest C&F wisdom is, In Search of the Optimum Bore, graphed on Hans Bracker's website.



BTW: C# is definitely not Bb.

[FrankFlute]

I am talking about whistles.
And you are right about the C# etc.
The graph is a great help.
So thanks.

[FrankFlute]

I mistyped, should have been A#
Corrected the subject of my own posts

[pancelticpiper]

For whistles, the latest C&F wisdom is (chart)

Interesting! Thanks Hans for that, and Tunborough for posting it.

Most interesting where the best whistles in my roll place on that chart.

Most of my best whistles, my Feadog D, Generation C, Generation Bb, home-made A, and Goldie Low D, are either at the very left limit line or somewhere in that left-hand (lightest green) band. My Burke Mezzo G is there too.

My great-playing Goldie Low C and Alba Bass A are off the chart, well to the left of the left-most line.

Two whistles peg that red centre-line, my Burke Low F and Burke Low Eb, which I regard as having bores at the limit of playability, giving huge bell-notes but stiff and slightly harsh high notes.

So my preference would be to move that red "optimal" line way over to the left, in the left portion of that left-most (lightest green) band.

C# is definitely not Bb.

B##?

[Tunborough]

So my preference would be to move that red "optimal" line way over to the left, in the left portion of that left-most (lightest green) band.

Interesting observation. I have on my desk a 12 mm Bb and 18 mm A, which come out as very narrow bore and wide bore, respectively, ... the limitations of readily available PVC pipe. Thanks to careful adjustment of the window size, both play a solid two octave range. But I confess I prefer the tone of the narrow-bore, small-holed, Bb, and find it much more nimble to play.

(When we calculated that bore table, we were considering only the tone. Smaller bores allow the toneholes to be smaller, which affects playability. That's another consideration.)

I think the shape of the curve, drawn from organ-building wisdom, is more important than the absolute position. We expect whistles in the same region of the curve to have similar playing characteristics, as you have experienced.

[FrankFlute]

So the smaller bores make it easier to play the second octave? But the bell-note will be weaker?

Considering the available routerbits, I have the choice between 12 or 16 mm.
I calculate the whistles with TWJCalc.
Both diameters result in models that I can build in wood.

So what would you advise? 12 or 16 mm?
My considerations:
When I want to stay on the left side (see above), the 12 mm would be better.
But what happens to the volume? Will I end up with a whistle that hardly makes a sound in the low octave?
Or can I compensate the volume by making the flue and the cutting edge 9 or 10 mm instead of 8 mm? On my native american flutes this increases volume.

[Tunborough]

So what would you advise? 12 or 16 mm?

To be honest, I think you're going to have to make one of each. For a Bb whistle, 12 mm would be considered excessively small, but nothing wrong with starting there if you're leaning toward a narrow bore.

I'd start with an 7-8 mm window (from the windway exit to the splitting edge) and trim it larger (little by little) if the bottom note is too touchy. 9 mm sounds too wide a window to me.

[pancelticpiper]

When we calculated that bore table, we were considering only the tone.

Ah, that explains it!

As it happens, tone/timbre is rather far down my list of most important whistle characteristics, which would go something like:

1. Tuning.

2. Voicing/action/nimbleness.

3. Air efficiency.

4. Timbre.

Other questions arise about you saying that the red line is where "tone" is optimised:

1) By "tone" do you mean timbre, or loudness?

2) If you mean timbre (as distinct from loudness) then what sort of timbre did you consider to be ideal?

3) What part of the whistle's range was used to determine "best tone"?

Thing is, my "red line" whistles, the Burkes, have a loud low octave but a rather bland timbre throughout the range. My whistles with bores to the left of that red line have richer timbres.

And the "red line" Burkes have the poorest timbre on "high B", tending to harshness, while the narrower-bore whistles have much smoother timbre on the high notes.

[pancelticpiper]

So the smaller bores make it easier to play the second octave? Will I end up with a whistle that hardly makes a sound in the low octave?

Yes as the bore gets narrower the 2nd octave gets easier to produce and the fundamental gets weaker, until you reach a point where the fundamental won't sound at all.

As the bore gets wider the fundamental/low octave gets stronger while the 2nd octave gets stiffer and harsher, until you reach a point where the 2nd octave won't sound at all.

Needing two octaves, the trick is getting the bore at the best compromise between those extremes.

Each maker finds the spot along the continuum that he feels is ideal.

[FrankFlute]

Thank's for all the contributions.
I will start with a small bore (12 mm).
And probably followed by a 16 mm version. Or I try a 12 mm routerbit on a depth of about 7.5 mm, which gives a somewhat more square bore, equal to approx. 14 mm diameter.
I will, in time, post the results.

[Tunborough]

1) By "tone" do you mean timbre, or loudness?

I wasn't being careful enough in my use of terms. We were aiming for a balance between the top and bottom of the range in the ability to produce a note, based on a property of resonance called the Q factor. In principle, diameters on the red line should yield about the same Q factor for "low D" and "high D" on the whistle: the low D should resonate about as well as the high D. The absolute position of the red line was based on Hans' experience with his standard bore, narrow bore, and wide bore whistles, which was consistent with estimates of Q that I've been able to calculate. The shape of the curve came from two different sources: collected wisdom of organ builders, and the properties of Q factor. Given your experience, you'll want to pay attention to the shape of the curve, and more or less ignore the position of the red line. Note that the shape of the curve gives a different result than simply aiming for a constant length/bore ratio.

[Peter Duggan]

Note that the shape of the curve gives a different result than simply aiming for a constant length/bore ratio.

How close is it to a constant length/cross-sectional area ratio?

[Edit: answered my own question. From a quick comparison of a few octave pairs, probably spot on.]

[pancelticpiper]

We were aiming for a balance between the top and bottom of the range in the ability to produce a note, based on a property of resonance called the Q factor. In principle, diameters on the red line should yield about the same Q factor for "low D" and "high D" on the whistle.

Interesting.

If by "high D" you mean 3rd octave D, how that note sounds is of little interest to me, due to me using whistles for tradtional Irish music.

The highest note commonly occuring in ITM is B in the 2nd octave, and if one assumes that Bottom D to High B range yes indeed the critical thing is "a balance between the top and the bottom of the range".

Now I wonder about another phrase you use, "the ability to produce a note", which to me is not denoting timbre or volume but rather ease of attack/responsiveness/lightness/nimbleness.

The red-line big-bore whistles are the worst at this attribute for the diagnostic B in the 2nd octave, diagnostic because it's the note with the most propensity for stiffness or non-responsiveness.

So once again my ideal, the best "balance between the top and the bottom of the range", is rather to the left of your red line.