Please refresh my memory… If the lower register is in tune and the upper register is sharp, which way should the cork be moved to bring them into happy correlation?
Thanks and best wishes.
Steve
Moving the cork away (toward the crown) from the embouchure will flatten the second octave, but go in small increments as it effects the notes higher on the flute differently than those with lower toneholes.
Thanks TKing.
Best wishes.
Steve
Some resources:
From J.J. Quantz, in his treatise On Playing the Flute (1752), Chapter 1, §11 & 12 (my italics in parentheses):
§11 When the flute is shortened or lengthened with the middle pieces (corps de rechange), the true intonation of its octaves will be lost if the plug (stopper/cork) remains always in the same position. It must be drawn further back from the mouth hole for each shorter middle piece, and must be pressed closer in to the mouth hole for each longer piece. (Note: the exact same principle applies to overall pitch adjustment by means of a tuning-slide instead of corps de rechange.)
§12 To determine whether the plug stands at the correct place, test the low D against the middle and highest D. If these two octaves are true, it is correctly placed. But if the highest D is too high, and therefore the lowest one too deep, draw back the plug until they are true. If on the other hand the highest D is too low, and the low one too high, press the plug further in until the intonation of both octaves is true. (Note that Quantz is referencing the middle D as his datum.)
From R.S. Rockstro, in his treatise The Flute (1890), Chapter 11, §331 & 332 (https://www.cs.dartmouth.edu/~wbc/rockstro/rockstro-tube.pdf)
§331 The Position of the Stopper. Theoretically, the stopper should be in a different place for every note of the scale, but as this is practically impossible we have to be content with a temporarily fixed medium position which may be changed under certain conditions. It has been found by experiment that the best results are obtained, on a well-tuned flute, when the cork is placed at a distance equal to its own diameter from the centre of the mouth-hole. A greater distance than this will cause the second octave to be too flat, and, while giving some increase of power and firmness to the low notes, will render the third octave difficult to sound and impossible to play at the same time softly and in tune. If the cork be too near the mouth-hole the second octave will be too sharp; the low notes will be weak and unsteady, and the third octave, though easy to sound, will be too sharp. If the finger-holes be correctly placed, any deviation from the true position of the cork will throw the whole instrument out of tune, even as regards the relation of the notes of each separate octave to each other.
§332 The effect of the position of the stopper on the pitch is far greater on the upper notes of each octave than on the lower notes, it is also proportionally greater in the second octave than in the first and greater still in the higher harmonics. This varying influence affords a means of correcting, to some extent, the intonation of badly tuned flutes, whether the errors happen to be the reult of imperfect construction, or of the drawing out of the tuning slide. It is impossible to lay down hard and fast rules for altering the place of the stopper, as the extent of the change that may be necessary will depend in great measure on the proportions of the bore, but it may be roughly stated that the stopper should be pushed in to an extent varying from an eighth to a quarter of the distance of the drawing out of the slide.
From the UNSW Flute acoustics: an introduction to how a flute works (The cork and the ‘upstream space’)
The cork and the ‘upstream space’
Between the point where the embouchure riser meets the main bore of the flute and cork in the closed end of the instrument is a small volume of air. The cork is normally positioned to be about 17 mm from the centre of the embouchure hole (for Böhm flutes!) (the exact value varies from player to player - see tuning wind instruments). Any very substantial variation seriously upsets the internal tuning of the flute. So how does this work?
This ‘upstream air’ acts like a spring - when you compress it, the pressure rises. The air in the embouchure riser tube can be considered as a mass. Together they can resonate like a mass bouncing on a spring (ie they form a Helmholtz resonator).This has a resonance over a broad range of frequencies, but centred at about 5 kHz. At much lower frequencies, which is to say over the playing range of the flute, it acts as an impedance in parallel with the main part of the bore, but an impedance whose magnitude decreases with frequency. The primary effect of this is good: with the cork correctly placed, it compensates for the frequency dependent end effects at the other end of the flute and so keeps the registers in tune with each other. On the other hand, it does reduce the variation in impedance with frequency when the frequency approaches the Helmholtz resonance, and so is one of the effects that limits the upper range of the instrument. If you push the cork in, as Charanga style players do, you can go further up into the fourth octave, but at the expense of having an instrument whose octaves are badly out of tune. If you want to know more about this effect, download our technical paper about it. To scale the highest reaches of the flute’s range, search for ‘high playability’ fingerings on the virtual flute and the report on F#7 and G7
The important message for flutists, however, is this. Among the orchestral winds, the flutes have the simplest method of adjusting their internal intonation. If your octaves are narrow, try pushing the cork in a little. If they are wide, pull it out. You will of course have to move the tuning slide as well.
And, from Tuning woodwinds
Flutes: check your cork. You probably have a centre marker on your cleaning rod, but there is nothing sacred about this position: you can experiment with it. Pushing the cork in raises the pitch of all notes, but it raises the pitch of high notes more than that of low notes. Pulling it out (screw the crown clockwise) lowers the the high notes more than the low. So if your high octaves are wide, you can pull the cork out. If narrow, push it in. If you move the cork to get your octaves sounding like octaves, you then have to change your normal tuning slide position.
From Terry McGee’s website (http://www.mcgee-flutes.com/FluteMyths.htm)
The “correct” stopper distance is one diameter of the head bore
Close, but not the complete story. The conventional stopper distance is one diameter of the head bore - about 19mm for the typical conical flute. But recognise it is a compromise, not a golden rule. A shorter distance - typically about 16mm - will enhance the third octave at the expense of the bottom octave. A greater distance - up to about 23mm - will enhance the bottom notes, at the risk of driving the top of the 2nd octave flat, and making the third octave hard to play and very flat. For Irish music, I recommend increasing the stopper distance until you find the highest note you normally play starts to tend flat.
And
Effect of Stopper Position - from which I will not quote at length here - go read it.
Hey Jem —
Thanks for the time, effort and expertise to find and transmit quite a load of information. It will certainly help me — and hopefully the next person with the same question (assuming the Search function is used).
Best wishes.
Steve
I’ve just compiled all the above plus a bit more into one of my help-sheets - now available to view or download here: Flute Stopper Position
I don’t know if it’s widely done, but I always used the note G for the setting of the cork.
It’s not just tuning, at least on my old flute: when the cork is at exactly the right spot I can play G in the low octave, then steadily introduce more 2nd octave G into the tone, until the tone is a 50/50 blend of low G and 2nd-octave G.
If the cork is the tiniest bit off low G will start fluttering then flip up to 2nd-octave G, in other words it resists having both octaves simultaneously present.
Are all flutes like that?