Speaking of grand pianos, we know that the key stroke goes through various stages: the hammer stroke, the moment when the repetition lever escapes, the fall, and then an important moment where nothing happens (aftertouch). I want to focus specifically on what happens from the escapement onwards. We know that the hammer's fate is twofold: it can fall suspended by the repetition hammer or it can be caught.
After this superficial introduction (certainly useless for technicians), I move on to the question. In a grand piano, it is quite normal to hear the "click" at the moment when the escapement occurs, except that I have noticed the consistency of this can vary greatly from piano to piano, greatly affecting the touch. On certain pianos (even new ones and even concert grands!), it is very present, leaving the pianist with a sensation of a "double keyboard" or double stroke: if approached lightly, the finger will depress the key down to the escapement, the strings vibrate, the hammer falls without being caught, but additional energy is required to reach the bottom of the key. In other cases, it is felt less, the keyboard is "easier," but personally I cannot pull much. What is the correct sensation and what adjustments does it depend on? Obviously excluding friction etc. I venture two hypotheses: the first concerns the spring tension (if none, the "double escapement" is nullified; if excessive, the hammer bounces, causing bouncing and the resistance is truly excessive). The other hypothesis concerns greater or lesser aftertouch. I have happened to notice almost zero resistance in Japanese pianos, especially in shops (to make the keyboard appear "easy"?). Obviously, I am taking for granted the various frictions which, if excessive, would be "highlighted" by a more loaded spring. Why this question? Because one finds various adjustments, various pianos; today we are used to playing even digitals where escapement... does not exist! Therefore, it is essential to become aware of what a piano should be, where perhaps we are prone to confuse what is right with what is wrong.
In fact, speaking of jeux perlee, you are talking about "two levels" of the keyboard. This translates to what I said, that in light touch (with a light touch) the finger feels the obstacle of the escapement as if it were the key dip? And then with a slight extra pressure, it is possible to play loudly and perform cantabile? Is it really that obvious? Obviously, I am talking about small sensations, not exaggerated ones that would suggest wobbling or something else.
In fact, speaking of jeux perlee, you are talking about "two levels" of the keyboard. Does this translate to what I said, that in lightness (with the 'i') the finger feels the obstacle of the escapement as if it were the key dip? And then with a slight extra pressure, is it possible to play loudly and perform the cantabile? Is it really that obvious? Obviously, I am talking about small sensations, not exaggerated ones that would suggest wobbling or something else.
I know the tutorial by heart too! ... In general terms, I would say yes ... Everything then depends on the type of piano you have under your hands; in my very personal opinion, nothing replaces your sensitivity when you test the dynamics of the instrument. I'll make a comparison with two pianos belonging to a friend: we tried to make an attempt, since he felt the touch was too decisive, to make it a little less direct. Still according to my opinion, there are pianos that give a sensation of greater smoothness and others that make you perceive less friction, even though everything is in order. There, it is your decision, within a certain limit, on how much you can act... Certainly, however, without straying too far from the standard manufacturer indications.
I have conducted various tests on my piano. I have come to the conclusion that it is all a matter of balance between friction and spring tension. Unlike other adjustments, this one is dynamic, not static: no manufacturer can ever specify a single amount of spring tension, but what governs it is the dynamics of the hammer returning after the escapement, decisively without too much "electricity". In light of my attempts, one must seek the lowest possible tension so that everything functions. This takes into account the fact that spring tension highlights friction; but greater friction requires greater tension, which in turn results in even more pronounced friction, creating a vicious cycle... Friction is not just a mechanical limit, but an artistic one, because it causes every choice to feel too "calculated". Jeux perlé is fine, many things are fine, but while I am playing, they must not lead me to mental quirks such as "now I am playing on the escapement", "now it's escaping" and so on ad infinitum. I should think about playing, "having fun" with the dynamics; the mechanics will do the rest. The ideal direction would be almost not feeling the mechanics at all, but sensing only the key and the hammer; sometimes a minimum of friction gives us a pleasant sensation. As for weights (the greater the masses, the greater the required spring tension should be), the problems should stem either from incorrect post-production weighting or from... friction! Factory weightings can be more or less refined and for fine palates, but they all more or less fall within high reference standards. I hope I haven't said anything inaccurate...
In reality, the escapement resistance is more evident or sometimes excessive in mechanisms with a return spring at the capstan. These instruments mount heavier hammer rails, even if they are less leaded. The spring supports the rail and pushes it upwards... but this does not change the ratio between the escapement lever and the hammer weight which, many times, is excessive, still increasing the sliding friction of the roller on the lever itself. This also causes excessive pressure on the roller, creating a "step" in the short term. And the problem increases. The ideal would be to eliminate the springs, refining the hammer tails and some pins or, where indispensable, replacing the hammer rail. Then, lead naturally while respecting the good ratio between downward weight and return weight. Furthermore, the return springs at the capstan of the rails are not applied up to the very last treble in all pianos. Thus, it forces more sudden weighting of the keys as soon as the spring itself "disappears." Nothing could be more unnatural.
