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PostPosted: Thu Jul 19, 2018 5:56 am 
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I want to relate an interesting experience I've just had, in case a) it helps anybody else, and perhaps b) others might be able to test, confirm or expand the experience.

A chap I know (here in Australia) dropped me down his flute for repair. It's a flute by a very well-regarded modern maker, very much a straight copy of a 19th century Rudall & Rose. The presenting problem was that the metal slide in the head had come loose, so I fixed that. But I found I was unhappy with the performance of the flute, so I went looking for other issues. Found one slow-returning key and one slightly leaking pad, so fixed those. Still not happy, but the flute leakage detector could find no further problems. This flute should work good. But low notes in particular were weak, unfocused and, when pushed, burbly.

Tuning sounded a bit weird to me, so I did an RTTA (Real Time Tuning Analysis) using Flutini. It revealed that we had two flutes rolled into one. All the notes from G# down were around 20 cents or more flat, while notes above soared up from A at +27 cents to a dizzying 46 cents sharp on low octave B. Second octave was better behaved, but centered around 20 cents sharp. I measured the C#-D# distance at 256mm. My flutes are circa 245mm. This flute retains the first-half 19th century scaling. Pitch was lower then....

Looking at the low D to middle D octave, it was about 33 cents wide of an octave. I felt this was a possible explanation for the weak and burbly low note response. It could be enough that the harmonics were not reinforcing as the wavefront returned up the flute tube to slap the jet out of the embouchure hole. So, how to flatten the upper note or sharpen the lower note? It's not my flute, so surgery is ruled out. Tempted though.... [Cue fiendish laughter off....] (Sorry, showing my age. Try: :devil: )

Keeping in mind that the top end of the flute was dramatically sharp compared to the low end, so I wondered if I could flatten it enough to make a difference, without also flattening it so much as to introduce a bigger problem at the top of the range. All I theoretically needed to do was wind the stopper out a bit. Temporary setback - the stopper proved immovable. Some irresistible force (gently applied!) fixed that. Secondary setback, the stopper screw shaft was jammed in the threaded hole in the cap. Fortunately, I had the right tap and die available to fix that. Finally, I could control the stopper position. I set it at 23mm (29/32") rather than the typical 19mm (3/4").

Wow! Dramatic improvement. What had been weak, fluffy, burbly low notes now seemed pretty focused and clear. Deluding myself, I concluded, perhaps a trifle uncharitably. Nah, you know this guy...

So I set the stopper back to 19mm, using my own cleaning rod to confirm. (I put markers at 15mm, 19mm and 23mm on my rods). Back to weak, fluffy and burbly. I repeated the experiment by resetting to 19 and then 23mm. Confirmed. Still, could just be me. I've had a cold and I haven't been playing at all. Coincidentally and fortuitously, we had a session planned for later that day. Coming back, much empowered by 3 & 1/2 hours hard playing, and found the same.

I then did another Flutini run with the stopper set at 23mm. Bottom notes still around -20, as you'd expect - the stopper position doesn't have much authority down there. But Low D to middle D deviance reduced to 23 cents (compared to 33). Low octave B now just +24 cents instead of +46. Second octave notes tending below 0 rather than circa +20. So the deviance has been significantly reduced.

Next day, the owner came down to pick up the flute. I mischievously set the stopper back to 19mm. I asked him to check it, and he thought it was playing normally. (Whew, I thought, at least I haven't made it any worse!) Burbly, weak, fluffy, I felt.

I got him to play my flute, and he got a much better bottom end, even though unfamiliar with it. He commented on that.

So then I set his flute to 23mm and asked him to play again. Dramatic improvement, perceived by both of us. He took it away, and has commented since via email: "Sooooooo much better." And later: "I have found a dramatic difference in the overall performance of the flute since you carried out the repairs."

Now, is this a fix? No. The tuning is still a bit poor. Interestingly, the owner is aware of this. Two really good concertina players had been giving him a hard time over it! It will be interesting to see if the stopper position tweak ameliorates their scorn.

And the performance still isn't as good as my flutes, as judged by both me and the owner of the flute in question. I think a fix would require re-scaling or at least re-reaming, to pull those really flat bottom notes up within reach. But it has made a pretty dodgy flute workable.

So, what am I hoping to achieve by telling you all this? International notoriety? Nah...

If you are playing a modern-made flute that is playing really well, this is all probably only of academic interest. But you do owe it to yourself to try adjusting the stopper position if you never have. Keep in mind the rules. As the face of the stopper approaches the embouchure hole, the third and higher octaves will be easier to play, but the bottom notes may become weaker. If you increase the stopper to embouchure distance, the upper octaves may get harder to play, and the upper notes may become noticeably flat. But the bottom notes may become stronger. The ideal stopper distance is not 15mm, 19mm, 23mm or any other. It's whatever works best for you.

But if you are playing a period flute, or a close copy of a period flute, and particularly if you struggle with a flat low end, you might have a similar experience. And resetting the stopper may well help you. Worth a few moments messing around to find out, I reckon!

And if you feel you need some technical backup, you'll find an RTTA system that suits your favourite platform starting at:

http://www.mcgee-flutes.com/RTTA.htm

I'm keen to hear from anyone who can corroborate (or refute!) that experience.

Woah, this has been a long post, but framing it has helped me get my mind around the important issues.

One final thought in passing. I've talked about modern-made flutes. I'm now over 70. When do I stop regarding myself as a "modern" maker?


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PostPosted: Thu Jul 19, 2018 7:55 am 
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Interesting Terry!

I set my stoppers around 23-24mm, including on my occasional Rudall Carte -derived flutes. Always. There is no rule for the 19mm - that is what is used on the modern cylindrical-bored flutes and the assumption is commonly made that this is the rule. There may simply be some orthodoxy involved. I've always found that these flutes play better with the stopper farther out.

As for tuners, I use an old but reliable Korg tuner that I compare with a few newer ones just to make sure its not going bad. Keeling the bottom D at zero, the middle D is always about 25c sharp along with the three leading tones below, starting at the A. The 2nd octave remains sharp following the same pattern. According to my ear though, the flute is in tune. Or at least I can play it in tune. I test it with the fixed stare session playing style as well as the modern style where the chin lifts a few degrees as one goes up the scale.

I think the difference is how the tuner - which is calibrated to perceive a tempered instrument - perceives the flute. I've had clients freak out that their flutes are out of tune, according to their tuners. I ask if they have a modern flute laying around and to test that for comparison and tell them to play a D major scale. They get the same result usually, and ask "How can that be?" Nederveen even published some tuner results in his acoustical aspects of wind instrument books and had a similar result for a number of flutes.

Also, a good experiment is to sing a D major scale and record that. Then see what the tuner does when the recording is played back. What sounds in tune (assuming one can keep good pitch control) doesn't look like it on the tuner!

There are all sorts of great examples of in-tune flute playing on YouTube such as this one of John Skelton playing one of my earliest Bb flutes:
https://www.youtube.com/watch?v=rtbKZ830yEE

It is the out of tune examples that are harder to find - but worth witnessing. Here is one. Ummm....enjoy?
https://www.youtube.com/watch?v=FCl0b77qB1w&frags=pl%2Cwn

This is a Miss Alaska candidate who went on to become a Republican Vice President nominee as well as the Governor of Alaska where she quit halfway through her term. She starts in tune (roughly) but then gets nervous and out of whack later on, or whenever she has to hold a note.

Casey

PS: The flute playing in this video is much better than the last one!
see https://www.youtube.com/watch?v=_iyIbbxVzrU&frags=wn

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PostPosted: Thu Jul 19, 2018 6:40 pm 
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Hi Casey

Yeah, I don't have any difficulty with making the now notes a little flat (compared to say A or G) as permission for the player to drive them harder without driving them sharp. So I guess the question becomes what's "a little flat" and what's "too flat". I would rate the flute I've been dealing with as "too flat". But even that is tricky. I've met flatter-footed flutes that can be driven well up, without encountering the weak burbling effect this one showed. So there's "kinds of flatness"! More work needed!

And yes, it's worth reiterating that there is no rule for 19mm. I think the 19mm assumption arose this way. Boehm observed that 17mm stopper set back produced the best results for his new cylinder flute. Coincidentally, that flute had a bore diameter at the embouchure of about 17.1mm. So the two parameters - stopper setback and bore diameter - became linked in peoples' minds. Then when Irish players started taking up 19th century flutes, they naturally assumed that the stopper should be set back one bore diameter, which is typically 19mm. When we look at the 19th century evidence, 17mm also seems popular. In this image Siccama not only puts a mark on the silver stopper position indicator but also puts a mark on the cleaning stick. It is 17mm from the end. But he was aiming at full 3 octave range. And his flutes didn't have flat feet!

Image

Now, I had a sudden epiphany in the middle of the night. I'd gone to bed wondering why pulling the low D octave back from 33 cents too wide to 23 cents helped so much. But when I awoke I realised that is probably not the main actor. It's the fact that all of the harmonics of Low D are moving in to help, not just the 1st harmonic. Let's see:

Note Partial 19mm 23mm
D4 Fundamental -16 -20
D5 1st harmonic 17 3
A5 2nd harmonic 11 -1
D6 3rd harmonic 8 -27

You can see that the 3rd harmonic (D6) is actually now tending a little flat of D4. Maybe that is a warning - this much and no further - or maybe it actually helps offset the somewhat sharp intermediate harmonics. The owner really needs to do some more experimenting to find out. The final setting is going to be what works best for him, not me.

And so should all of us!


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PostPosted: Thu Jul 19, 2018 7:17 pm 
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Another observation. Remember I'd reported:

"All the notes from G# down were around 20 cents or more flat, while notes above soared up from A at +27 cents to a dizzying 46 cents sharp on low octave B. Second octave was better behaved, but centered around 20 cents sharp."

So when you get to the session and turn to the concertina player, what note do you ask for to tune to?
Low D -23 cents
Low G -20 cents
Low A +27 cents
2nd D +17 cents.

There's a "hole in the middle', no real "median note". 2nd octave G or Eb probably comes closest at +5.

Pulling out the stopper does narrow the range, but the hole in the middle remains. So it's a workaround, not a fix.

Siobhán! Give us an Eb5 if you don't mind....


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PostPosted: Fri Jul 20, 2018 7:59 am 
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All interesting Terry! I personally haven't made much study on the tuning peculiarities of flutes except perhaps when measuring something I want to capture. In those cases I usually select something intact and in tune.

As far as my own flutes, I set the stopper where the flutes seem to play the best for my embouchure. When making the flutes I'll voice the embouchure with the stopper at this average position and then tune up the 1st octave to pitch by sizing the 6 finger holes with tapered reamers. Sometimes I need to move up the bottom D which I can do by counter reaming the bore (this is done only with a shorter foot, instead of one with 2 vent holes)

Usually the 2nd octave notes above G are flat at the point after the 1st octave is tuned and the flute will play a little bit stuffy. I will then, using a burr on a Foredom handpiece, undercut the fingerholes and test the 2nd octave pitch.

With the plug set at 19 to 21mm the degree of undercutting the C#, B and A holes can be minor. But at the 23-24 position, much more undercutting is required to bring the 2nd octave in tune. It is also complicated with the 0XX 000 and 0X0 XXX first and second octave fingerings for C which will go sharp as these holes are tweaked. Iteratively over several flutes I stay on top of it. But as no flute bore is exactly the same on my flutes (my style allows and evolves by allowing some flexibility) its always a dynamic process of discovery.

Generally undercutting all of the holes opens up the tone in a lovely sort of way.

I wonder if by looking at the degree of undercutting of these top finger holes if one can roughly determine the correct setting of the plug on a vintage instrument. I am sure that I am not the first maker to deviate from any orthodox "standard". I've measured some nice Metzers that had fairly steep undercutting and play well to me. This would be an interesting thing to quantify.

Casey

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PostPosted: Sun Jul 22, 2018 6:14 pm 
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Heh heh, all this has prompted me to test the effect of moving the stopper on my flute. I remember I used to have it further out (around the 23mm mark) years ago, but then decided to "re-educate" my embouchure to blow down more for the darker tone. For some reason, I decided at that time to revert to the more typical 19mm. But playing with it now, I reckon there is a noticeable if not dramatic improvement at the greater distance. I'll leave it there for a while and see what I conclude.

Interesting that not all flutes react the same. I have here an original flute by Jordan, Liverpool. I've fixed it up, but am still not content with its performance. Great, I thought, let's try a greater stopper distance. But it made it worse! It seems to work better at a lesser stopper distance if anything. More work needed....


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