Light action (HELP)

[ATodd@UH.EDU]

   I recently excerpted some of the things said recently on this list about
light/heavy actions, coming out of the Hamburg vs American question I posted.
After reading the following post, I feel as though I'm out of my depth to
accurately answer the questions asked. And these are from a piano teacher, not
a technician. I have some ideas/opinions about a few of the questions, but
feel like I cannot adequately answer all of them. Can/will some of you help?
I'll forward any answers I get to the piano list.

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>The key to all of this is that as soon as you move from down and up weights
>to balance weights, you've answered the first big issue in touch resistence,
>namely, is your problem one of friction or of mass. So many people describe
>touch resistence in terms of down weight (and if we're lucky, up weight as
>well), but this is meaningless to me without the differentiation between the
>two kinds of resistence.

Don't we have to distinguish between three parameters, i.e. friction,
static weight and dynamic weight, the last being inertia?

In an ideal world there would not be friction, but a certain amount of it
is, I guess, inevitable due to the mechanics of the piano. Friction however
is sometimes confused with weight when it comes to the general feel of
playing a piano.

>A piano can be on spec in regards to downweight and feel dynamically
>anywhere from heavy to light.

That is, if the static weight (the down and up weight) is on spec we still
have to deal with the dynamic weight, or rather a product of the friction
and the dynamic weigth (inertia). Now if the friction is as low as the
mechanics of the piano will allow, in other words if the piano is well
regulated, we are still left with inertia, which is the absolute weight of
the key. This weight can be increased by using more lead at either side of
the balance point without changing the down and up weight at all. A concert
grand will have more inertia due to the longer keys which need more lead to
be balanced correctly relative to the mechanics. Is this explanation
correct, Avery?

Inertia becomes important in fast play, as it seems more difficult to
accelerate the key due to the quantity of mass that has to be moved. When
paired with a high down weight it becomes almost intolerable.

The question could be what is the most decisive element when it comes to
the feel in the fingers, leaving friction aside, is it the static or the
dynamic weight? As an example what would be the difference in feel of the
two: a low down weight with high inertia or the other way around?

I agree that Yamaha feels lighter than Kawai as some of you have remarked,
but I am also interested in knowing about other brands that have a light
feel, and perhaps why this is so. From what I have heard Bluether and
Bechstein are examples of this.

>As for the touch, I've played "heavy" Hamburgs and frighteningly light NY
>actions with everything in between.

What is the reason they vary so much?

Finally, what is the exact relation between weight and repetition? Is a
very light action invariably connected with slow repetition, maybe due to a
low up weight?

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   I have a feeling that this is a pianist/teacher who would keep ANY tech
on his/her toes!!
   Thanks in advance for any help you can give me.

Avery Todd, RPT
University of Houston
atodd@uh.edu