When I get a brand new wooden flute, how much should I be able to sharpen it or flatten it with the tuning slide? I’m talking about both physical distance as well as cents between notes. There must be a mechanical limit at which it shouldn’t be pulled out anymore, but I’m not experienced with that. I would think that the flute should be in proper tune at mid-point of this range. You could use a typical blackwood pratten-bore flute as an example, since that’s the type of flute I’m curious about. Thanks for any help you can give.
It’s one of those “how long is a piece of string?” questions, but let’s see if this answers your question.
Making small changes on a real instrument and trying to measure them is not easy as, every time you put the flute back to your lips, a slight change of angle tends to blow the repeatability out of the water. So I’ve run a computer model to determine the effect of pushing the slide in and out by 5mm (3/16"). Not surprisingly, the results are pretty symmetrical, but there are slightly different effects in the two octaves.
In the bottom octave, a 5mm change will cause about 30cents change at c# (ooo ooo) and about 15 cents at low D (xxx xxx). Notes between lie pretty much on a line between those two.
So our flute pulled out or pushed in 5mm would be about 20 cents flatter or sharper at A, but the extremes (low D to c#) would be out of tune with the A by up to 15 cents.
Note incidentally that the model validates the old 1Hz/mm rule of thumb. 20 cents above 440 Hz is 445Hz.
In the second octave, the effect on middle d (oxx xxx) is about 15 cents also, but the effect on notes above that is not quite as noticeable as in the lower octave, so by the time you get up to the high B, it is only around 23 cents affected. High c# is about 25 cents affected, but the model is assuming you will play that using the third harmonic of F# (oxx xoo), as ooo ooo in the second octave runs dismally flat unless vented by a c hole.
So we will see a small deviation between the octaves as well as along the flute. But at 5mm extension or compression, those deviations are quite lippable. I’d say you would start to notice problems by the time you got to 10mm.
Fortunately, these effects more or less counter the effects of different embouchure hole coverage - the reason we mostly use the tuning slide. So the effects mentioned above will probably not be as noticeable in real life.
Incidentally, the model I was using was based on a large hole, large bore Rudall, but the results will carry over to the Prattens.
Terry
Wow. Thanks for all that, Terry.
So, a particular flute would definitely not be optimal if, at 68fahrenheit/20celsius room temp, it needed to have its tuning slide pushed all the way in for the first note, and then pulled out by approximately 3mm after being warmed up with 15 minutes of continuous play. That flute would need to have at least 2mm more leeway to sharpen it by 20 cents, and optimally it should be able to travel even more than that, right?
That’s where it becomes a “length of a piece of string” question. How sharp does one need to go? If you play with fixed instruments, as long as you can get to A440 on a cold day you are right. But if you routinely play with a piper whose pipes are a bit sharp (as they often are), or if you are a player that plays particularly flat (as many do), you may need more wriggle room.
Rockstro used to recommend that a well-tuned flute would be at normal pitch (in those days around 452-455) when withdrawn 1/8" (3mm). But then he was dealing with Gentlemen (ladies didn’t normally play in those days) who went to lessons from Professors. Our wacky world of Irish music is nowhere near so predictable - we have to allow for conservatorium trained players who play across the instrument, and self-taught players who cover much more hole and blow down into it. The difference in produced pitch is surprising.
Generally the less a tuning slide is open, the better, so the maker has to settle on a compromise, putting the embouchure hole where the flattest player is still able to get up to normal pitch. Tough when the flattest player also has a friend with sharp pipes!
And then there’s the Rudall & Rose Patent Head - a head with a 30mm range on the slide, to optimise the stopper position over the range from below 430 Hz to 460. Although it does successfully optimise the stopper position, keeping the third octave working across that range, it does nothing for the bigger problem of detuning the flute. Even Rudall & Rose had to obey the laws of physics. Funny that they didn’t bring back the old corps de rechange idea - it would have done a much better job than the Patent Head.
So, given our wacky world, it would be a brave person who argued for an optimum position of the slide!
You can see incidentally why, on my slideless flutes (the Minimum Disruption Tenon head), I was concerned to minimise the disruption that the gap in the socket creates when the head is extended. I reckon a 3mm gap is about all you can live with in the normal barrel socket, but 3mm is going to be not enough to tune some sharp players if I locate the embouchure hole to allow for the flat players. The Minimum Disruption Tenon approach gives me a bit more wriggle room.
Terry
As a related aside, one flute that I own has a series of engraved rings on the visible portion of the slide, which enables you to accurately gauge where you have the slide set, and return to that position reliably (i.e. where the flute is most in tune with itself or where you have to play most often with others.) If you regularly play on several flutes with different embouchure cuts, it is also very helpful to mark the slide so that you can set the head angle reliably.
My own take on this is that my flute is like a fiddle with one string.
I have to tune to different instruments constantly. The heat of the room matters, as does humidity and what I had for dinner and how loud the place is (how hard I have to blow) and what shape my embouchure is in at a given time and how long the flute has been on my lap or the table while I’ve not been playing for a short or long time (how hot or cold it is) and whether, or what, I am drinking.
The tuning slide only brings it into a rough, approximate tune. The final tuning has to be done on the fly, by my lips (embouchure) and the position of the flute on my lip. There is no ignoring tuning as you play and as you go from octave to octave- especially high in the second octave.
After a while tuning on the fly becomes automatic and instinctive but you still have to do it. Rare is the fiddle - even with one string - that stays in tune the whole night. Terry skirts the issue, but really - there is no such thing as optimal tuning or tuning by the marks on the tuning slide.
So I’m not misunderstood - my point about marks on the slide is that at least you start out in the same place each time. To me this is particularly important if you are playing on a number of instruments which require different headjoint angles.
Obviously, you adjust from there and tune on the fly constantly.