TONE HOLES, diameters & ratios

These pages give tone hole dimensions and compare these to the width of the bore at the spot. The comparison produces the ratio of both cross-sections.

Diameters of tone holes are given in millimetres with an accuracy of one tenth of a millimetre. The ratio between the tone hole and the bore is given as a percentage.This ratio presents a measure of the relative openness of a tone hole. In relation to this openness, key lift heights ought to be considered as well, but are not given. They're subject to regulation and as such not a very stable quality of the instrument itself. For an overview of the historic development different instruments are given: the 'first generation' and the 'second generation' of Adolphe Sax saxophones (the second generation is easily recognizable by their narrower bell, but essentially is a complete redesign of the instrument). Next a later 19th century French instrument; a choice of earlier and mid 20th century French and American instruments; a later 20th century French, an odd German and finally an example of the modern Asian instruments.

Tone holes are numbered from the bottom up. Consequently the hole which plays (written) Bb – B is hole no 1 and the hole which plays (high) E – F is hole no 22. Register holes are numbered 23 and 24. The hole which in history came last (F – F#) is hole no 25. On some sopranos you'll find a hole no 26 for high-G. The hole which plays low-A – Bb on a baritone is numbered zero, in order to make the numbering of all the other holes run parallel. Similarly, in the very early instruments tone hole numbers run parallel to the modern, producing numbers without a tone hole. Several things are to be noted:


Soldered-on tone holes in the very early instruments are often out-of-round. They're measured in different directions and the size given here is an average value (soldered-on Martin tone holes are turned on a lathe and are rather accurate in size). Drawn tone holes can be out-of-round as well and most certainly show minor variations in their sizes in different specimens of the same instrument due to the process of pulling them out of the tube.

Measuring a tone hole is not as straightforward as it might seem: a bit more pressure on a vernier calliper makes it show a tenth or so wider a value. Moreover, the percentage value of the relative opening is based on a measurement of the tube width as well. The tube width at the spot of a tone hole can, of necessity, only be taken in one direction and therefore is prone to the out-of-roundness mistake. As a consequence, the proportion between the two can only be interpreted as indicative. A few percents more or less between two kindred instruments does not mean that much. You're on the safe side if you conclude that in such a case both tone holes under comparison are identical.

As in bore profiles, so it goes for tone holes as well: a saxophone is not a precision instrument. Nor does it need to be: as a rule of thumb a tone hole has to be made smaller a 10 percents for a flattening of around 10 cents (you raise the diameter of a given tone hole to the square, subtract 10 percent of this value and next extract the root. This is your 10% smaller tone hole). And although we still strive for an optimum compromise, 10% deviation in intonation is easily within the range of your embouchure control. Most instruments suffer from this kind of faults. Take it as an advantage when you want to differentiate between a G# and an Ab.