Following the example of the alto saxophone with only open keys, the next one was bound to be a tenor.
Here the use of only one tone hole per position, as in the alto, was dropped. I kept tonehole 13 and its mechanism (Ta) as it was. Also, I dropped the altenative lay–out layout of key nr 18 (the possibility to obtain a C via the bridge between the right and the left hand key stack), as I never used it in the alto.
I changed the way in which mechanisms for keys 3 and 5 were build. Here I choose the more efficient switch mechanisms for both keys, instead of the spring loaded mechanisms used in the alto. These switch mechanisms are more complicated to build, yet easier to regulate and far more reliable.
My open keys tenor was made on the basis of a Taiwanese Evette clone, by the name of Condor, an instrument lacking the high F#3 which the Evette still does have. There are some more minor differences. This instrument, I think, is entirely unknown in Europe. The Taiwanese Evette is yet definitely akin to the Buffet–Crampon Syperdynaction and S1 models in bore profile and tone hole dimensions. And so is this Condor.
The slide show goes from top to bottom along the finished instrument, starting at the tone hole for high Eb...
Key nr 11 (G–G#) is normally a closed key. The third finger left hand operates key nr 12 and because of the closed position of key nr 11 we still obtain a G. Both keys are changed into open keys and now both need to be closed to get a G. Key 11 can be reopened by the little finger left hand by a switch mechanism such as we use in the automatic octave mechanism.
It is not possible in this layout of the mechanism to additionally obtain an Ab as a lowering of an A via the bridge between the right and the left hand, such as for instance Leblanc does in the «le Rationnel» saxophone. This option namely is incompatible with the automatic mechanism of the G# and because this G#-function has in the meantime become an integral part of saxophone mechanisms, it was given precedence over the Ab-option.
Tone hole nr 12 is a rather large tone hole with an built-in cross fingering correction. The size of this hole was reduced to a more normal proportion.
Next key nr 5 (D–Eb) was changed into an open key. Normally, key 5 is a closed key. The third finger right hand closes key nr 6 and because of the closed position of key nr 5 we still obtain a D. Here too, both keys were transformed into open keys and now both need to be closed simultaneously to obtain a D. Key nr 5 got a hinge at the left hand side of the instrument and is connected to key 6 via a swich mechanism, closing keys 5 and 6 at the same time. Via the switch we can reopen key 5 in the normal way by the fourth finger right hand.
Moreover, it dawned upon me that, since key 5 has turned into an open key, a second «petit» is now possible: an added spatula providing an added fingering 'half a step down' for the second finger right hand to obtain an Eb instaed of an E - in the same way as a Bb is obained instaed of a B by the first finger left hand making half a step down. We have to learn to use it, but you can now play the scale of Bb-major by just adding or lifting a finger! And since the conventional fingering for Eb remains valid as well, it is just a very nice addition.
Tone hole nr 6 too is a rather large tone hole with a built-in cross fingering correction. The size of this hole was reduced to a more normal proportion.
Last but not least: key 3 (the "low C#-key") is normally a closed key. This one too was changed into an open key and its switch mechanism is operated by a linkage to key 4 (the "low C-key"). Here too, the two keys are now being closed at the same time. Next, key nr 3 can be reopened in the usual way by the little finger left hand. The fingerings for C and C# thus remain the same.
Here too, in a similar vein as the new P2, an extra spatula in the fingerplate for the fourth finger right hand could have been added for an only-one-finger-low-C# and since key 3 normally links to key 2 (to prevent the key from unwittingly being opened when a low-B is taken) the consequence would have been that from this new fingering for low-C# you could proceed to low-B or low-Bb by adding only the fourth finger left hand. Very convenient indeed!
However, since I'm not sure of the mechanical accuracy of such a mechanism and since I'm not convinced of the ergonomic correct placement for the extra spatula, it was not (as yet?) executed.
It goes without saying that the location and size of tone hole nr. 4 were corrected as well.
Was it worth it? Again, yes, and even more so than in the alto. The sound of the instrument especially in the low range and in the lower end of the second register is richer and opener. There is probably a wee bit more power to the sound but, like the alto, the instrument also speaks more nicely at low levels, especially over the greater lengths. The issues in intonation with the tenor are not as acute as in the alto.
As in the alto, the switch mechanisms work flawlessly. It turned out well that the tenor was equipped with this kind of mechanisms all over as they are far more idiot-proof than the mechanisms used in the alto. Spring tensions were not altered, even lowered where possible and are thus not necessarily higher than in a conventional mechanism. However, for the larger switches of the larger keys 3 and 5, which are both operated with a little finger, you do feel that there is some more mass to be moved. The new P2 is something to get accustomed to, but, like the P we already know, it comes in handy.