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MMD > Archives > March 2002 > 2002.03.22 > 11Prev  Next


Effect of Key Length and Piano Regulation
By Craig Brougher

Many comments have been passed about the effect of key length
on the piano's touch.  I'm here to say it has no effect at all.  The
only time that key length would have any effect on the touch of a key
is if the key were to deflect or bend in the striking process.

One person correctly noticed that the Steinway D has longer keys in
the bass than in the treble, and yet the touch is more even throughout
the scale in that piano than any other American-made concert grand
I am familiar with.  The reason is because it was meticulously
touch-weighted.

The only factor you have to deal with is another point brought up by
Larry Lobel: the ratio of the leverage.  However, I have not found this
to be consistent.  For instance, Chickering's ratio was 1:2.6 in their
quarter-grands, and other action companies used 1:2.5.  Since shimming
the whippen rail by just a few thicknesses of paper will greatly change
the touch of a piano (stiffening it), it makes no sense to reinvent the
key fulcrum ratio.

As far as momentum goes, that's also inapplicable.  Momentum is a
function of mass times displacement over time.  The key's momentum,
versus the hammer's momentum is the ratio that's important here.
So since the key's momentum, even for a huge key, is so tiny compared
to the hammer's momentum, it makes no difference at all.

Some have noticed that their Duo-Arts have a "lumbering" feeling when
hand-played.  Let me assure you this is not because there is more
lumber in the action!  It's because the action has not been completely
rebuilt or regulated, or cleaned and regulated.

For instance, Steinways have a sliding spring that travels in beef
tallow (in vintage instruments).  That stuff turns to hard sludge as
the phosphor bronze of its spring gets added to the mix, along with
dirt and lint.  To clean these slots, the action has to be taken apart,
and many techs don't want to go to the trouble, and many customers
don't want to spring for the full monte, so it works both ways.

A Duo-Art should have the silky smooth action of any piano, and if it
doesn't, you have something that could be improved.

As far as striking distance of 1-7/8" as opposed to 1-3/4" for "short
keys," this is also inapplicable.  All technicians should own the PTG
Piano Action Handbook.  In it they will see that almost all grands have
either 1-7/8" or 1-3/4" hammer blow.  It has absolutely nothing to do
with the key length.  And if it had, then we should expect the Steinway
model D to have 1-7/8" hammer blow in the bass, and 1-3/4" hammer blow
in the treble.

Trust me when I say that you can regulate a Duo-Art action as finely as
you can regulate a regular action.  There is absolutely no difference,
either in speed, or dynamic range, or smoothness.  As a matter of fact,
the shorter the overall key length, the more critical the leverage
becomes and the more difficult it is to weight the keys.

Craig Brougher

 [ Good quality necks for guitars have a stiff insert laminated into
 [ the length of the neck to reduce warping, and I understand that
 [ some new banjos use a metal stiffener.  Titanium would be great
 [ for stiffening banjo necks and piano keys: it's very stiff and
 [ very light weight.  One problem, though -- it's very expensive!
 [ -- Robbie


(Message sent Fri 22 Mar 2002, 15:11:46 GMT, from time zone GMT-0800.)

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

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