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PostPosted: Fri Feb 28, 2020 3:32 pm 
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For the makers out there, I'm curious if anyone has ever done some testing to isolate the effect of the conical bore on tone/playing characteristics. For instance, keep the mouthpiece constant, but made a straight bore and a conical bore whistle for it? If so, what were your results?

I ask because I've enjoyed a number of conical bore instruments, and there seems to be something in the tone that is similar, at least for the ones I've played. I know that tuning is often cited as the reason behind the conical bore design, but I haven't noticed well made cylindrical bore instruments being out of tune.

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PostPosted: Sat Feb 29, 2020 7:20 am 
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There's at least one person who conducted that experiment:

"All wind instruments with tone-holes, whose construction requires very accurate proportions, can be improved only through the investigation of both good and bad existing instruments, and through a rational application of the results...theory and practice go hand in hand.

For this purpose I had prepared, in 1846, a great number of conical and cylindrical tubes of various dimensions, and of many metals and several kinds of wood, so that the relative fitness of each as to pitch, ease of sounding, and quality of tone could be investigated.

The most desirable proportions of the air column, that is, the dimensions of bore best suited for bringing out the fundamental tones at various pitches, were soon found.

...the formation of the nodes and segments of the sound waves takes place most easily and perfectly in a cylindrical flute tube, the length of which is thirty times its diameter, and in which a contraction begins in the upper fourth part of the length of the tube, continuing to the cork where the diameter is reduced to one tenth part."


Theobald Boehm, The Flute And Flute-Playing

In my opinion Boehm is correct, and to me cylindrical Low Whistles play better than conical ones, in general. Whistlemakers don't do the Boehm-style curving contraction at the top, rather they tend to use a sudden contraction which seems to work fine.

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PostPosted: Sun Mar 01, 2020 12:30 pm 
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pancelticpiper wrote:
There's at least one person who conducted that experiment:
...the formation of the nodes and segments of the sound waves takes place most easily and perfectly in a cylindrical flute tube, the length of which is thirty times its diameter, and in which a contraction begins in the upper fourth part of the length of the tube, continuing to the cork where the diameter is reduced to one tenth part." [/i]
Theobald Boehm, The Flute And Flute-Playing

In my opinion Boehm is correct, and to me cylindrical Low Whistles play better than conical ones, in general. Whistlemakers don't do the Boehm-style curving contraction at the top, rather they tend to use a sudden contraction which seems to work fine.


I've noticed many Irish, Indian and PVC flute and whistle makers be concerned about adding the Fajardo wedge or tapering the headjoint for a portion of it's length, to allow the second and third octaves to function smoothly with the first, and to help intonation. That matches the idea Boehm mentions regarding the "upper fourth" of the tube. That we see many whistle designs without that, has probably been worked out by exploring all possibilities available with mouthpiece/blade/window design options. Most silver flutes and some Irish flutes have a slightly tapered headjoint tube while the body remains a cylinder. It could be that the conical portion of the tube doesn't really help the function of the musical instrument, for the conical part to extend beyond the top 1/4. Some models make the whole tube conical, but to what level of success, or of discovering an appealing option? The fine folks at Shaw and Clarke would probably like to comment on that. But in all cases, how a whistle or flute actually function is of course a combination of the conical/cylinder design options working with the mouthpiece area design chosen, so if we look at a Shaw or Clarke conical design, we also have to consider the design of the mouthpiece area on it's end result. If you take a Shaw, cut off the mouthpiece area and stick on the mouthpiece off a Killarney, what would happen? Wonders.


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PostPosted: Sun Mar 01, 2020 12:58 pm 
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RoberTunes wrote:
. . . cut off the mouthpiece area and stick on the mouthpiece of . . .

prior maker-wannabee here . . .

One of my early experiments: mix+match different mouthpieces on different (straight) barrels. Biggest takeaway: the "voice" followed the mouthpiece. "Voice" being the "timbre". Also, the PSD shape pretty much followed the mouthpiece.

Unfortunately, my little exercise didn't include a conical barrel. . . maybe someday . . .

trill

ps:

I've tried making Low D's. . . they made sounds alright, but had numerous weaknesses compared to the pros.

I've tried making mouthpieces. . . oh boy, one mis-file and you're in a different voice !

I've also played straight-bore, conical-bore, + perturbed-bore instruments.

One of my later PSD studies: try to replicate the "voice" of a beautiful sounding instrument by using the PSD as a guide for modal-component-superposition. Start with just a few low peaks and add more+more content at higher+higher frequencies. The finding: oh boy, all those little-tiny modes at higher+higher frequencies matter a great deal !

My guess: the tapered bore combined with axial-flow yields viscous effects (turbulence) which gives rise to all those high-frequency components. Honestly, though, just a guess. . . something I'd like to investigate but have no time for.

Note also: the tapered bore alters the bulk-modulus-per-length ratio as well as the end-of-tube flow resistance.


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