"Run a scale evaluation to make sure it wouldwork"????????????//

[Delwin D. Fandrich]

----- Original Message -----
From: "Phillip Ford" <fordpiano@earthlink.net>
To: <pianotech@ptg.org>
Sent: Monday, March 31, 2003 3:58 PM
Subject: Re: "Run a scale evaluation to make sure it
wouldwork"????????????//


>
> >One of the problems that is still prevalent in the practice of rescaling
> is
> >the gap that exists between the nice lines on the computer screen and the
> >reality of the physical piano. Some of the worst examples of rescaling
> that
> >I've been called on to correct have actually looked rather nice on the
> >screen and on paper.
> >
> >Del
>
> Would you give some examples of rescaling that looks nice on the screen
and on paper but doesn't work well on a piano?
>
> Phil F


Several problems that come to mind are overall tensions that are too high
and bass scales using core wires that are too small. Even "concert grand"
scales don't need scale tensions that are all that high yet I've seen scales
on smaller grands averaging up in 180 to 190 lb range through the tenor
section. Unless the backscale is really, really long this tends to restrict
the motion of the bridge and soundboard assembly. In placing too much
emphasis on the inharmonicity coefficient one can easily end up with core
wires in the bass that are too small to provide an adequate grip for the
wrap wires. There are mechanical limits to what can be done.

Another is the topic that just recently came up. If the tenor bridge is
pretty much straight across a plate break it is possible to even out the
tension by making the treble side a bit larger and then dropping back down
on the bass side. Within limits this does work. But I've seen jumps as great
as two wire sizes here. For example, on the treble side of the break a #17
wire might be called for while on the bass side of the break it might be
necessary to drop back to a #15 wire to even out the tensions.
Unfortunately, this is going to be just as bad as the original. It's far
better to compromise even though the graph lines are not as clean.

Or consider the low end of the Steinway B tenor bridge. Tensions drop from
the 165 to 170 lb range at F-33 down to approximately 120 lbs at F-21. (It
varies from piano to piano.) Now, it is possible to bring the tension of
F-21 up to 166 lbs by going to a #24 wire (0.053")--and I've seen it
done--and this will make the graph look pretty good (except for the
inharmonicity line) but it sounds pretty bad. Much better to install a
transition bridge and switch to wrapped bi-chords for the first five notes.
Or, if this is not in the budget, even switching to a few bi-chords on the
same bridge will be an improvement on the original.

Good rescaling is always a compromise between some mystical ideal and the
realistically practical.

Del