Halvesies.

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an seanduine
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Re: Halvesies.

Post by an seanduine »

Craig Fischer´s ´Squinter´ works well enough, but people with much better ears than I, have pronounced it somewhat lacking in harmonic richness. Perhaps this is an artefact from the hard inside corners. David Daye did some work on square whistles as well.

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Terry McGee
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Re: Halvesies.

Post by Terry McGee »

Sedi wrote: Thu Jun 17, 2021 4:09 pm
Terry McGee wrote: Wed Jun 16, 2021 10:13 pmYou can prove that easily by inserting say a thin knitting needle up the head. Really screws with the aerodynamics.
That's how the "tuning rod" on the German marching band flutes by Sandner work. The Sandner "Zauberflöte".
I don't have a pic but you can see a schematic in the fingering chart:
https://www.musiker-board.de/attachment ... jpg.97924/
But it does indeed weaken and dampen the sound when inserting it too far. Since it is exactly in the middle I guess the air circles around it to a certain degree. It can be used to correct the octave tuning on a cylindrical flute but kind of messes up the low notes, which are not that important on those marching band "fifes" since they are played more in the 2nd and 3rd octave. So it wasn't a great solution for an Irish-style flute. I quickly abandoned that construction. Still got two flutes I made with those. The 2nd octave is nice and it plays easily into the 3rd. But the low notes suck :D .
Heh heh, my experience entirely Sedi. Yes, in theory the vibrating air column spirals around the centrally mounted tuning rod, but clearly not well enough! It should strengthen the low notes by improving the alignment of the partials, but instead it really messes with them. A case of aerodynamics beating acoustics.

I also wondered if it might work better for the "blowing across" style of embouchure rather than the "blowing down" style we tend to prefer. But I lost interest in it!

Fajardo's wedge is the other approach sometimes put forward as a way of improving a cylindrical flute. A tapered wedge is inserted from the top of the head to make the cylinder more like Boehm's head bore in cross-sectional area. But I think it messes with the spiral too, just not as badly. Probably best located just under the lip, to minimise its effect on the spiral.

But awildman's approach will let him make the bore any shape he wants, and avoid all these workarounds.
awildman
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Re: Halvesies.

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In theory, Terry, yes, I can make just about any bore profile. The problem is that I don't know what bore profile to use for most things. My current project is based on measurements from an old 1800s boxwood clarinet I have. I'm just following directions at this juncture, so to speak. It will be quite a while before I get a handle on the acoustics side of things.

I'm not sure that aerodynamics and acoustics are friends. Relatives, yes, but not perhaps on the best of terms. We don't want the air to flow better, do we? We want it to vibrate in a certain way, and efficiently. It seems to me that it would be more efficient to keep the same vibrating air molecules inside the instrument as long as possible.

Perhaps high airspeed makes a difference, but rounded cavities a la golf ball dimples create a swirling effect that lessens air resistance. Check out Mythbusters episodes about the golf ball dimple car, and the pickup truck with rear tailgate up vs down. I have never heard of anybody doing such a thing inside a woodwind. Muddying up the airstream with air swirls seems like a bad idea to me.
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Terry McGee
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Re: Halvesies.

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awildman wrote: Fri Jun 18, 2021 12:31 am In theory, Terry, yes, I can make just about any bore profile. The problem is that I don't know what bore profile to use for most things. My current project is based on measurements from an old 1800s boxwood clarinet I have. I'm just following directions at this juncture, so to speak. It will be quite a while before I get a handle on the acoustics side of things.
Which is how we lathe users started out too. I think it's a natural progression - you work out that you can make something, then find something to make, then want to make it better, then want to make making it better, and so on. Just be aware that making your first woodwind is an established gateway drug. Who knows where I might have ended up if I hadn't make that bad turn in 1974/75. Investment banker, perhaps?
I'm not sure that aerodynamics and acoustics are friends. Relatives, yes, but not perhaps on the best of terms. We don't want the air to flow better, do we? We want it to vibrate in a certain way, and efficiently. It seems to me that it would be more efficient to keep the same vibrating air molecules inside the instrument as long as possible.
We have to dissociate DC (Direct Current) flow - the relatively slow movement of all the air in the tube down towards the end because we are blowing some air in the top end, with the AC (Alternating Current) flow - the fast back and forward motion of any one molecule in the middle of the tube as part of the vibrating air column. We don't have to worry much about the DC, it looks after itself. We do have to protect the efficiency of the AC, because that's what translates to sound as it leaves the flute. Both poor aerodynamics AND poor acoustics can mess with the efficiency of the vibrating air column.
Perhaps high airspeed makes a difference, but rounded cavities a la golf ball dimples create a swirling effect that lessens air resistance. Check out Mythbusters episodes about the golf ball dimple car, and the pickup truck with rear tailgate up vs down. I have never heard of anybody doing such a thing inside a woodwind. Muddying up the airstream with air swirls seems like a bad idea to me.
I'm imagining that the flying golf ball is a DC event - the ball is heading in one direction only, at a relatively fixed speed. Here, clearly, the dimples assist its travel by reducing air resistance. But our air molecules are tiny, and are rapidly moving back and forth (eg 440 times a second for low A, several thousand times per second for upper harmonics). I can only imagine that any roughness in the surface will be much bigger than the molecules and give those molecules near the walls a really hard time. Hence any work we can do to smooth their path and keep it smooth is well rewarded.
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