[Solved? ] Bringing low D into line on Rudall short foot

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GreenWood
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[Solved? ] Bringing low D into line on Rudall short foot

Post by GreenWood »

[I put a ? in title because it is half solved, design needs understanding and refining to be practical... this is for an original bore shape but short foot Rudall ]




I tried to figure out how it is that 1st octave D is so low vs. 2nd octave on Rudalls . I have some thoughts on that but not certain for now, so will not write them. However, what would need doing to raise 1st D at foot (or lower 2nd) seems clear enough.

Apart from introducing toneholes (basically a long foot) which keeps 2nd close to 1st, or redesigning the bore (cylindrical towards end as an "impedance thing" or whatever and have seen glass flutes try this I think) there are not too many choices maybe. Some short foot Rudall based D flutes must have this solved I think by changing bore profile ?

Obviously there is player embouchure, using more air (whether jet or open) to keep 1st high and so close to 2nd. Then there is lip cover in 2nd (or down angle) to bring down 2nd. This is going to be different tuning for a flute possibly, for example playing base notes medium pitch and 2nd lower compared to base notes high and 2nd medium ). Those are all workable to one degree or another and will be decided by, or decide, the style of playing. So just having found this

http://www.geertlejeune.com/flutes/tuning

I think he is more or less right on the lowered bass being part of playing style of the day...not that other better/"better" arrangements weren't possible.

Anyway, from a physics and sound point of view and without ruining tone and apart from large reshaping of bore , the options of how to keep bass 1st octave notes in pitch at medium playing effort are maybe more limited. Restricting the bore exit ruins tone and has not too much effect on discrepancy unless near unsoundable . Widening the bore will lose tone, but I expect will bring down 2nd more than 1st, probably not enough. Pratten has wider bore angle from top, hence wider foot, so designed that way via whole bore...if they have foot in tune ?

So the only other ways I could think of, both not tested, are :

Pic

Image


1. Mechanical, and barring having a ridiculously long lever to close bore at foot with first tonehole finger lifted...well the following idea is mechanical all the same, and though in principal I would not choose it for being so , others might find use. Other valve types are possible, of varying sensitivity. Simply, the through hole vents higher for 1st octave, but higher pressure 2nd closes it so giving full bore length for 2nd. In grey is a basket construction, but other forms of valve support exist.



In fact it might be fun designing a flute that had no finger holes only these, and as you increase blowing pressure they open (in this case, not close) one by one up the tube, with second octave not by overblowing but simply further of those higher towards embouchure...and if someone hasn't made a flute controlled by battery powered servo motors yet, well I think one day someone will...vast array of possibilities doing so... but it is not the kind of idea I would take up, or nescessarily what an instrument should be.


OR

2. By allowing some entraination of air higher up the flute. A simple miniature tonehole muffles the tone though and doesn't seem to bring them into line much either. I might try a ring of mini toneholes that allow 1st to reflect at higher pitch when blown low but don't affect when blown stronger, but I think the answer is probably by using some form of entraination, not venting per se. So idea at left is entrainment (as ring around flute) and right is venturi. Higher air speed in 2nd pulls in more air than 1st, increases pressure further down, lowers note compared to 1st.



several hours later cont. .....

BUT

3. The following actually worked , and brought 1st and 2nd octave to right in line and at good pitch, medium blowing steady and nice tone for both and no change embouchure etc. :-D

Image


@ 5mm dia. soft pipe, 20cm long with blutac at base. Connects over tonehole 6

Just by playing around, I was planning to feed some venting into end, but no need.

So there is some trial and error needed there to find out how it works, minimum parameters possible etc., and though maybe other designers have bore solutions (I don't know), for new amateur builds I think a reduced design could be carved into the body of the cylinder leaving tonehole 6 as normal. Tonehole 5 open is weak with the mod attached, but clearly the mod when finished would have its own tonehole (or feed from side of 6) , leaving 6 open and working as normal, and so 5 also.

The unusual thing is that just reducing tonehole 6 at surface does not work, so there is some kind of "smooth change of impedance" added by having a tube there.



For those with confidence it would mean hacking an existing flute (but don't until others have trialed it to get best design). For those with an instrument not to be adjusted it could be a retrofit where tonehole 6 is raised by a platform that feeds the vent... not that I think many would want to do that.

So, for anyone with a Rudallish flute and finding base notes just too much, maybe try the bluetack and plastic pipe shown and just see if it works on your flute, and how that sounds. I will probably carve this in on my flute, so will write up on that if I do.

What will be good is for someone to figure out exactly why it works... maybe someone will come up with a much more compact way of doing the same... I haven't played with the design yet so that is what I will try to figure.

Finally, a thank you to Tonehole for inspiring me to find a solution to tuning on a short foot :-) .

I'm mostly offline at the moment and just posting this then back offline, so if I don't reply to anyone for a while that is why :thumbsup:
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Re: [Solved? ] Bringing low D into line on Rudall short foot

Post by Tonehole »

Wonderfully inventive part-solution!

I could follow most of it, although I found my solution the Rudall Rose short foot more elegant - I got rid of it and traded for a better modern tuned Rudall Rose copy :lol:

As lovely as historical flutes are, and they do hold their own position and legacy, a modern contemporary conical bore flute is a more elegant solution. Waiting to see your idea come into the mainstream. I might have a 6 hole flat footer lying around somewhere. I think it's off by way more than Geert's projects of -30% - more like -70% !
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Re: [Solved? ] Bringing low D into line on Rudall short foot

Post by GreenWood »

@ Tonehole - thanks and yes, I figured modern design had overcome this.... but I haven't tried any flutes by other makers yet so I don't know how in tune they really are....

......

So, well I had to carve this into the flute and I will write up on that and other ways to achieve same. For now there is a sound clip here.


https://e.pcloud.link/publink/show?code ... zyMFizld70

This is all blown straight and even, no embouchure change etc. First sample is original flute (@ 60 cents) [ ed.in 50 cents in recorded example, min 20 cents by pushing low D and bringing down 2nd octave but not easily playable like that] , second sample is with made modification (under 20 cents) , third sample with blutac and pipe (exact).

Although the carving I did has @ 12mm sq cross section , there is more resistance to straight pipe (because of inlet placement/shape probably) which is why there is still some discrepancy, but I will leave it as is because it plays and I don't feel like undoing work done :-) .

So, I don't know how much of a problem this is for other flutes, more experienced makers or players will have tried many, I only have those I make plus recordings and online discussion to go by. Normally bore shape change etc. has solved this discrepancy ?

Either way, this modification helps learn about what is going on with dynamics of this flute. Normally I aim for a ten cent range (+- 5 cents in other words) , but here it will be a 20 cent range, still very playable. The Rudall has a vast range of pitch for base notes, I can take low D from C -25 to D +25 , over two notes (hz 430). If played rolled out a touch pushing D with this mod it is in pitch between octaves without rolling in for 2nd , or slight embouchure cover for 2nd brings that straight etc.

Well, if this design hasn't been thought up before (added venting from around first tonehole [ed.in meaning TH6] for D notes ) , I get to label it, and call it The Tonehole Mod. (after Tonehole :-) ).

...offline again now for a while.....

:thumbsup:
Last edited by GreenWood on Mon Nov 22, 2021 12:31 pm, edited 1 time in total.
GreenWood
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Re: [Solved? ] Bringing low D into line on Rudall short foot

Post by GreenWood »

This is a description of the moification made to a Rudall style flute to bring low D into line between octaves, plus a few other ideas...

https://e.pcloud.link/publink/show?code ... JfJFBN3Ymy
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Re: [Solved? ] Bringing low D into line on Rudall short foot

Post by Tonehole »

Hi -

I get this message when I try and click on the link: "The site ahead may contain harmful programs

Firefox blocked this page because it might try to trick you into installing programs that harm your browsing experience (for example, by changing your homepage or showing extra ads on sites you visit)."

I didn't realise modifying the flat D foot problem was so contentious :lol:

One other elegant solution: find a C foot of a parallel flute and swap out the short D foot. I am amazed at this solution - the only thing missing is the stamping of the maker's name on the short foot section!
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Re: [Solved? ] Bringing low D into line on Rudall short foot

Post by Tonehole »

Cross-reference this post with views about the longer D foot: viewtopic.php?f=2&t=107697http://forums ... 2&t=107697
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Re: [Solved? ] Bringing low D into line on Rudall short foot

Post by paddler »

For what its worth, nearly all of the short foot antique flutes I have studied have a flared bore at the foot,
produced by back-reaming for a few cm from the foot end. The long foot flutes do not have, nor need, such a flare
because the pair of open-keyed foot holes (for C and C#) are sized and placed in order to produce the same balancing
effect. The underlying reason is to do with the "end-correction effect" (in the case of the short foot) and "venting
influence of the down-bore open tone hole lattice", being different for low and high frequency notes. Changing
the foot bore shape, or the downstream open tone hole lattice parameters (hole size, position, undercut, etc), in
just the right way (for a given bore) allows the two octaves to be brought into balance. In practice, I believe this is
done mostly by a process of trial and error, or by copying an existing flute that has the desired playing characteristics.
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Re: [Solved? ] Bringing low D into line on Rudall short foot

Post by Terry McGee »

C-footed flutes do have the flare, but it's much, much smaller and only extends back 30 or so mm (just over an inch) from the far end. And only flaring a mm or less from the minimum. While a D-foot (Short foot) flare can extend back to the socket and flare several mm.

Check out these "classic bores I have known" from my website:

Image

You can see the start of the foot, typically around 320mm and identified by a sudden jag in the bore taper.

Interesting to remember that D-footed flutes (eg baroque era flutes) came first. When the C foot was first added, it caused a lot of angst, with players complaining it "ruined" the low notes. When you add the shading produced by the normally-open C and C# keys, and the dodgy tuning a lot of the early C-foot flutes displayed, you can sympathise!
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