Flute acoustics: measurement, modelling and design - School of ...

9.2. EIGHT-KEY FLUTE BY RUDALL &ROSE 137
(i.e. there is no slide position and—by inference—no design pitch where the flute is perfectly
in tune). In most flutes the stopper and the tuning slide are not coupled, and many flutists
(perhaps the majority) tend to adjust the tuning slide regularly but leave the stopper position
unchanged. For small changes in pitch this is perfectly acceptable, since flute tuning is much
more sensitive to the slide position than to the stopper position. However, for large changes in
slide position the tuning can be significantly improved by concomitant changes in the stopper
position. Many different pitches were in use in the 19th century and flutes were designed to
play adequately (if not well) over a wide pitch range. For a detailed discussion of the many
pitches in use in the 19th century, see Terry McGee’s web site . The following comments of Terry’s (shown in italics) explain the problem of different
pitches, and how various makers tried to accommodate them.
Before the 19th century, pitch was considerably lower than the modern standard pitch in
which the note A4 is assigned a frequency of 440 Hz (denoted by the shorthand A 440). 17th century
French flutes work well around A 392 (a whole tone lower in pitch), and A 415 is taken as
a convenient pitch for the late baroque (18th century). In France and Germany, pitch had stabilised
by the early 19th century to A 435, but in England, where this flute is from, a wide range
of pitches were in use.
A flute by Richard Potter in the Bate collection in England is a good example of how this
was first dealt with. Dated at 1782, it has three interchangeable left-hand sections (corps de
rechange), giving pitches estimated as A 418, A 427 and A 436. The three bodies, which differ
in length by a total of 18 mm, are marked ‘4’, ‘5’ and ‘6’ to denote their pitches. Not long after,
Potter introduced the tuning slide as a cheaper way to achieve the necessary tuning range. He
continued the tradition of denoting the pitches with incised rings on the slide, also marked ‘4’,
‘5’ and ‘6’. Conscious of the fact that the stopper should be moved to get the best results at these
differing extensions of the slide, he had an indicator rod sticking through the cap, marked with
corresponding rings.
A professional musician might encounter at least three different pitches in a day: e.g. an
older organ in a church tuned say to A 410, a domestic piano at an afternoon tea tuned to just
over A 430 (actually C 256), and a Philharmonic Orchestra concert at a pitch as high as A 455.
Attempts were made by the Society of Arts to compromise these to A 445, but the Philharmonic
movement stuck to their guns until 1895, when they suddenly accepted 439 Hz (only marginally
higher than the Continental A 435). 439 being a prime number was dropped in favour of 440 at
a later international conference on the basis that it could not easily be generated electrically.
So, the tuning slide had to deal with a range of at least 25 Hz (the difference between the
Philharmonic orchestra at A 455 and the domestic piano at A 430) and maybe more. According
to the flutemakers’ rule-of-thumb that a pitch change of 1 Hz corresponds to a change in length
of 1 mm, this implies a movement of the slide of at least 25 mm. Apart from adjusting the slide
to attempt to encompass these wide ranging pitches, a corresponding change was needed to the
stopper to restore, as well as can be achieved, the internal tuning of the instrument.
In 1832, Rudall & Rose patented a mechanised way of keeping the stopper and slide in their
optimum relationship, so by then all our the player had to do was wind the stopper cap for best