Animisha Is this typical for Kawai? Or do all dp's / controllers have this problem?
There are no even piano keys. They are all uneven. But the longer the keystick, the less dramatic the effect with the increased force near the fallboard.
Details:
Everything is just physics. Lever principle to be precise. This happens if the pivot point of the key is relatively close to the fallboard. Most digitals of all brands have issue. Exceptions are only the expensive ones with the long keysticks like Kawai GF-III, Yamaha Grandtouch and Roland Hybrid Grand action.
Some upper midrange actions like Kawai GFC and Roland PHA-50 have the keystick at least long enough to reduce this lever effect to an acceptable result.
Both my Kawai RH-III action as well as your RM Grand II have only about 20 cm long keysticks (15 cm visible, 5 cm behind the fallboard to the pivot point). Let's do a little math. The cm-value is always the distance from the pivot point to the center of the chips pile. E.g. The gray pile is about 2 cm away from the fallboard plus additional 5 cm keystick behind the fallboard. This makes about 7 cm in total:
White keys (+5 cm behind fallboard):
- B / gray: 7 cm * 329 g = 2303 g*cm
- C / red: 13.5 cm * 164 g = 2214 g*cm
- D / green: 18 cm * 131 g = 2358 g*cm
The black keys have the pivot point a bit further back (+ 6.5 cm behind the fallboard):
- G# / blue: 8.5 cm * 231 g = 1964 g*cm
- A# / black: 15 cm * 154 g = 2310 g*cm
You see, the g*cm value is quite consistent every time, with the blue pile as a minor exception. I guess this could be caused by a lighter escapement-notch on that specific key. I increased the weight until the escapement notch "clicked".
For the physicists:
If you don't like <g*cm> because it sounds unscientific, let's factor in our earth acceleration of 9.81 m/s2 and we get this:
2300 g*cm * 9.81 m/s2
= 2300 * 9.81 g*cm*m/s2
= 22500 g*cm*m/s2 ..........................| replace <g> with <kg/1000>
= 22.5 kg*cm*m/s2 ........................... | replace <cm> with <m/100>
= 0.225 kg*m*m/s2 ........................... | replace <kg*m/s2> with <N> (Newton)
= 0.225 N*m (Newtonmeter, the SI-unit for torque)
q.e.d. 😏