we started this project with the question whether or not we have lost 'something' in the course of history by straightening the cone and if so, at the expense of or in the favour of what?
A first answer can be given to that question. By straightening the cone we've gained in stability and in correct intonation, especially over the greater lengths. But we've lost also. It must be admittted that the things we've lost are of far more of a subjective nature: the horn's more massive sound, its resistance. Yet, developments, both for (most) classical and jazz music, go into the direction of a brighter sound with more partials added. And resistance? For the jazz musician it's defenitely not an issue. Anyway, we can now ascertain that both cone-shapes are not equal and the disappearance of the one shape also means a loss in musical possibilities.
The instrument, as it had got this far, was submitted to the criticism of several professional muscians, some of whom are familiar with Adolphe Sax instruments. There were two principal points of critique. One outcome was that people were unhappy with the remaining instability in the lower end. Low-E is stable under all conditions, but then sensitivity starts and grows worse and worse as we descend. Another criticism concerns its intonation behaviour. It is true that not much attention was paid to that, thus far, just accepting the three necks in combination with the tone holes as they were – which certainly wont't do in the long run. A third remark referred to both registers not really 'belonging' to one another.
Happily enough, two original altos by Adolphe Sax were available for acoustical investigation; the one being the 24495, which in the mean time had been brought into a playable condition; the other one is its one year younger brother 25095, also in playable condition. It turned out that the 24495 tuned rather well to A=435Hz, whereas the 25095 tuned to A=440Hz. Also, tone hole lengths of both instruments are not identical, which confirms that the instruments are not intended for the same concert pitch. These two altos definitely were not built on the same mould. Along with these, there was an original Adolphe Sax mouthpiece, which was used with both instruments.
It turned out that both Adolphe Sax instruments were unstable themselves in their lower ends in the same fashion as my horn (progressively from Eb downward), albeit less annoyingly so, and both of them not to the same amount. To a certain degree, that was quite a relief... The 25095 is by far the most stable of the two, although the 24495 improved when fitted with the neck of its younger brother. It reminded me of the behaviour of the first generation Adolphe Sax tenor, which is discussed in the page on the 1866-patent in the History-section.
All three instruments share a certain blowing resistance which is higher than in the modern alto. Presumably this resistance is generated by the type of bore profile, is just part of the concept. It facilitates longer musical lines. Common wisdom has it that a higher resistance comes from a large–chamber mouthpiece, but this obviously is only partially true: most of the higher blowing resistance is due to the parabolic cone. One of the side effects is a stronger tendency to produce wind-to-the-tone. Insomuch as we do not want that, precaution has to be taken in shaping the tip rail appropriately (which, by the way, also causes this type of mouthpiece to not produce the intended sound on a modern instrument).
It is remarkable that, as mentioned before on the page «THE MAKING OF THE BORE», the kind of instability under scrutiny goes hand-in-hand with too too wide octaves over the greater lengths (low-B(b) up to low-C#) and even the lower end of the 'right hand' (D, D# and E) of the saxophone. Although too wide octaves over the greater lengths are more or less common and accepted, the measure of sharpness experienced here is greater than what we're accustomed to. Or, to put it differently, when we would succeed in reducing this sharpness, chances are that the instability would be reduced as well. As a secondary result, both registers would be much better interconnected.
When we closely compare the bore profiles of both Adolphe Sax altos (the 25095 is not documented in this website) with one another, we see that the 24495 is just a little bit wider over almost its entire length. Only in the last end of the bottom bow and the entrance to the bell the 24495 is narrower than the 25095, creating an even more pronounced parabolic bore. My tribute–horn shows a similar shape. This might contribute to the acoustical problems, as it provides an extra contraction at the open end of the bore in the tonal regions which are troublesome. This offers an interesting start for further experiments.
Also in the neck there is room for further development of the form.
The Adolphe Sax 25095 and my «tribute–horn», side by side.