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MMD > Archives > March 2002 > 2002.03.21 > 14Prev  Next

Effect of Piano Key Length
By Larry Lobel

Responding to Randolph Herr's questions to me:

> Since the key length definitely and absolutely has an effect on
> manual playability, could you please tell me what this effect is,
> and how strong it is?

It depends on how the action designer solves the problems introduced
by the elongated key.  The optimal location of the fulcrum point of a
key is one that gives a 1:2 ratio of the front segment to the rear
segment of the key; the more deviation from this ideal, the harder it
will be for the performer to exert control.  Lengthening the keys makes
it necessary to compromise away from this ideal.

> On a typical grand piano, the depth of touch is 3/8", and is
> "balanced" so that the capstan rises half that amount, or 3/16".
> On a Duo-Art with long keys, the depth of touch is 3/8" and the
> capstan rises 3/16".  Is seems to me that the two different length
> keys are balanced so that the ratio of dip of the front of the key
> is twice the distance the capstan rises.  Don't these keys have the
> same "balance" (a word that I define as the ratio of key lengths
> just mentioned)?

Not necessarily, for the reason I gave above.  The geometry of piano
actions is complex and other factors are involved besides key dip and
capstan rise.

> I was really surprised the first time I ever saw an action being
> removed from the nine-foot Concert Grand Steinway "D".  Because of
> the scaling of the strings, the keyboard has longer keys in the Bass
> than the Treble, and the keys for the Bass section use keys as long
> or longer than those keys found in a six foot Duo-Art, so why is this
> long key effect not complained about by the artists who play the
> nine-foot "D" ?

Optimum key leverage and touch weight across the entire scale is
non-existent on any piano, and pianists have become accustomed to this.
The longer keys in the bass may be a compromise away from the ideal,
but are also a benefit because of the heavier hammer mass that must be

> It is entirely possible that there are such effects, however in many
> years of thinking about the subject, I am yet to find any effects,
> and so I seriously believe that if there were such effects that I
> would have heard them by now.  But I wouldn't want to bet my life
> on it, either.

Piano designers, builders and technicians have devoted a lot of
thought and experimentation to understanding the mechanism of the piano
action over a period of 300 years, and the subject is not settled to
everyone's satisfaction.  But there seems to be general agreement that
the slightest change in any parameter will have significant effects

Robbie asked:

>[ How does PTG define key balance and key weight, and what
>[ adjustments can the piano tech perform?  Can the balance point
>[ (the fulcrum) be shifted?  Should this be necessary?

In recent years this subject has been extensively studied and
experimented with.  Actions can and have been extensively redesigned,
including relocating balance pins, capstans, knuckles, and lead weights
in the keys.  This often is necessary to obtain optimal performance,
because original designers/manufacturers did not always achieve this,
even by Steinway and other top quality makers.  David Stanwood, RPT,
has created a new science of piano touch weight metrology and is
acknowledged by many to be the expert on this subject.

Larry Lobel

(Message sent Thu 21 Mar 2002, 16:34:55 GMT, from time zone GMT-0800.)

Key Words in Subject:  Effect, Key, Length, Piano

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