One of the points of departure in this project is the use of only one tone hole per position, such as Sax had done in his instruments. Yet, we would like to keep the layout of a modern mechanism. So the idea is to develop a mechanism without parallel tone holes which still retains all the possibilties of a modern fingering. Also, the way in which Sax in his third patent and in alto 40842 lays out suggestions for a more developed design of the mechanism deserves closer attention. A separate page in the History-section is devoted to this design.
The «open-keys-alto», which is described in the instruments-section, served for study purposes. In this instrument everything is rather pushed to the limit. That is not the intention here. This mechanism uses closed keys on tone holes nrs 3, 5 and 11.
The example of the Ad Sax 40842 leads to an additional linkage for key nr 18. Key 18 (the "C#-key") is normally being closed by keys 14 and/or 17 and plays the major role in obtaining a C. When this key is also connected to key nr 15 (the front Bb-key or P) it is possible to obtain a C and a Bb via the bridge between the right and the left hand key stack. The C is only slightly on the sharp side and well within the margins as we already know them from the fingerings 0,2 and 1,Tc.
Key 16, Tc, is preserved. This key so much has a position of its own, that its function cannot be replaced by another layout of the mechanism of keys nrs 15 and/or 17.
To begin with: in addition to the oridinary automated octave mechanism, the instrument got an extra register key to fascilitate overblowing the greater lengths. Not only does it provide an intonation advantage for middle Eb and D, but from there, you now can go down to middle Bb, offering another sonority than the short, open fingerings. Sax already described this fingering in his 1866 patent.
The linkage from key 18 to key 15 under the P-spatula makes a C playable as a lowering of a C# in very much the same way a Bb was already playable as a lowering of a B, using the second finger right hand.
The new mechanism for Ta functions like a switch, in which the position of the key depends on two variables. As usual, key nr 14 is closed by the second finger left hand but only when the Ta is at rest. When the Ta-touchpiece is operated, the key opens again. As for fingering, there is no difference here with an ordinary mechanism, but we need a tone hole less.
The method used in the Ta-mechanism is not possible for the Tf, because the first finger right hand sits directly on key nr 9 itself. Tf is now connected via the back side to key nr 10, which, when operated, closes. This means that the semitone is obtained as a flattening of a G and not as a sharpening of an F. Here too, we use one tone hole less, but the substitute mechanism calls for an adaptation by the musician. On the other hand, new combinations of fingerings arise: the Tf also lowers G# to F#, B to Bb and Db to C.
For the rest the mechanism is conventional. I have been thinking of a one-finger-low-C# mechanism in the same way as in the Leblanc «le Rationnel» saxophone. Such a mechanism could be made with a switch in a similar vein as the mechanism for Ta. It is an experiment I did execute in the «open keys» soprano saxophone, which is described in the instruments-section, but which I considered to have no concern with this particular project.
In stead I payed some more attention to the easy slidability of the plateau for the left hand fourth finger.