Last week we talked about a 50-point checklist and knowing what changes are taking place during action regulation. A three-question quiz was also given which will be repeated here:

1)    Does regulating the jack height to the balancier affect the strength of the repetition spring?

2)    Does regulating the let-off affect the backcheck distance?

3)    Which of the following affect the amount of aftertouch: key height, blow, jack alignment, jack height, let-off, drop, backcheck, repetition spring?

Now that a month has passed to think about the answers, wouldn’t it be great if there were some place to turn to look up the correct answers? How many of us have taken the time to thoroughly investigate and think out what happens in grand action regulating? Everyone should own or have access to a grand action model. These are a great help in trying to figure out a problem or to understand the hows and whys of the working parts.
Here is a grand regulation chart which lists the nine action regulation steps and how they directly affect each other. (You can find the chart at the bottom of my last post. It’s the 2nd graphic.) X’s mark steps which are affected, O’s mark those which are not.
It should now be quite easy to find the answers to the quiz. The answer to question no 1 is yes. Think of the butterfly type repetition spring as now used in Bosendorfer, Steinway, and Yamaha grands. As the balancier is raised or lowered to the correct height above the top of the jack, the tension on the repetition spring is changed. Think of the balancier and whippen as opening and closing like a jaw. The tension on the spring increases as the balancier is lowered. However, the effect this style of spring has is the opposite one would expect. Even though the tension increases, the hook of the spring moves forward (toward the keyboard) in the spring slot on the bottom of the balancier. This necessitates the spring tension to be increased in order to achieve the same effect, since the point of contact is now further from the balancier’s flange.
In answer to question no 2, the grand regulation chart is marked no. Now it is possible to argue that if the key is depressed slow enough, as when we regulate the let-off, and if the let-off is changed considerably, that the hammer will check at a different height. True, but the main factor here is not the let-off distance. Rather, the speed at which the key is depressed. In actual playing, the hammer must continue to move upwards after let-off in order to strike the string, then it falls back, going into check Changing the let-off only changes the amount of power that the key gives the hammer. The backcheck distance does change, of course, on whether the player gives the key a hard or soft blow. On a hard blow, the hammer rebounds more forcefully into the check position and ends up a little lower. On a very light blow, the hammer may not even go into check. Anyway, we can be pretty safe if the backchecks are regulated before the let-off, since as can be seen on the grand regulation chart, the backchecks only affect the repetition spring strength.
For the third question, the factors which affect aftertouch are:
1)    Key height. Changing the key at the balance rail affects the key at the front rail by a factor of about 1:2. Adding a 0.010 balance rail punching will increase the dip, and hence the aftertouch, by about 0.020.
2)    Blow. Piano actions are designed so that the dip to blow ratio is about 1:5. Changing the blow changes the amount of key dip needed for total escapement. When we raise the capstan to lessen the blow distance, the effect of raising the whippen puts the jack tender closer to the letoff button and the end of the balancier closer to the drop screw. This causes escapement to happen sooner in the stroke of the key, giving more aftertouch.
3)    Jack alignment to the knuckle. Since the jack has a double function of raising the hammer and also causing let-off, regulating the jack to the knuckle changes when the jack tender engages the button. Therefore, if the jack is moved inward, toward the keys, the tender moves down and away from the let-off button, creating escapement later in the dip, meaning less aftertouch.
4)    Let-off.From what has already been said, it is obvious that let-off directly influences aftertouch. Making the let-off closer to the string creates less aftertouch.
5)    Drop.If drop is defined as the amount that the hammer drops after let-off, and that aftertouch is defined as the downward movement of the key after drop, then the amount of drop is proportionate to the amount of aftertouch. Decreasing the amount of drop increases the amount of aftertouch.
Notice that on the grand regulation chart the first left to right column is marked dip. This is the column which is read for aftertouch, since aftertouch is a part of dip. The factors which do not affect aftertouch are the jack height, backcheck distance, and the repetition spring strength. Of course, the jack height and repetition spring indirectly affect the aftertouch by affecting the hammer blow distance. But this chart only shows direct relationships.
Having answers to questions like these is a great help in figuring how to approach the specific action at hand. Remember last week’s post that the order of section IV “The Touch” of the 50-point checklist may be changed to suit the needs?
IV. Touch
31) Jack height to the balancier
32) Blow
33) Let-off
34) Drop
35) Aftertouch
36) Backcheck distance
37) Repetition spring
38) Check gram weight resistance all 88 keys
39) Adjust key stop rail 
This order would be fine for dealer preparation on a new piano. But what about an old action where the repetition springs are weak? (Remember “the circle of five steps”? See the 1stgraphic in my last week’s post.) Then the jack height will vary each time the key is played, making it impossible to set the hammer line straight. In this case we could not begin with setting the jack height and blow distance. Rather, we should start with the backcheck distance and go immediately to strengthening the repetition springs. A quick glance at the grand regulating charts shows that only two steps affect the backcheck distance. One is the key height which was set in step #12 on the checklist. The other is the dip. So after setting the dip be sure to go back and readjust the backchecks! See how easy it is with the proper information at hand? Now you can start with setting the jack height and blow and go on as is listed in IVTouch.
Remember in selecting the proper sequence in this IVTouch section that those steps which affect the others the most should be completed as soon as is possible. In reading the far right-hand total column we see that the key height and blow affect four other steps versus only one or two for the other procedures. Therefore, try to adjust the key height and blow first. Similarly, make sure that the dip is one of the last steps to be completed, since as seen in the bottom column, five other steps affect it.
Now that we have a grand regulation chart which shows how each step affects and is affected by another, we can use it as a check while going through the 50-point checklist. A checkup and a check! If we go one step further and put them both together along with a “how to”, an excellent guide will be created which will help anyone through regulating a grand action. Coming up in the next post, an enormous 50 – point guide to grand regulation.

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