Scale design question

[Michael Jorgensen]

To Del Fandrich, Dampp Chaser, and Other
      How much consideration is given to tuning stability in
scale/board/bridge/rib design?   Much focus is on even tone and smooth
temperament over the break.  That is all good,  but  how about making the low
tenor so it changes more equally with the rest of the piano in a weather
change?  How possible is that?  How much sacrifice would be needed?
       Dampp chasers systems really help,  but I find it hard to keep folks
from unplugging them.  We need battery operated "Plug this unit in" beepers for
churches.

-Mike Jorgensen
Tuning instability could kill the acoustic piano.


Delwin D Fandrich wrote:

I can't speak for the others, but in the Baldwin 243 studio -- at least as I

> redesigned it in the mid 1980s should make the transition between tri-chord
> plain steel wires to bi-chord wrapped wires between F-33 and E-32.
>
> F-33 in this piano is only about 812 mm (approx. 32.0") long. This is very
> short for a steel string. In this scale it is a #21 wire (0.047" or approx.
> 1.2 mm) and still has only 158 lbs (approx. 71.7 kgf) of tension. While I
> would normally consider this tension to be quite adequate in a piano of this
> size, the way the original tenor bridge was laid out the tensions just an
> octave or so above this were averaging upwards of 200 lbs (approx. 90.8
> kgf). My mission -- which I chose to accept -- was to make the scaling less
> bad without spending any money. This precluded making any substantial
> changes to the plate. Things like relocating the V-bar were out of the
> question.
>
> To go any lower with plain steel wires in a scale this short would have
> required using an even thicker -- more massive -- wire, something I didn't
> want to do. It makes the tuning transition from plain steel to bi-chord
> wrapped even worse than normal and they generally sound pretty tubby.
>
> This piano has the bass-tenor break at C-28/C#29. I don't know why this
> crossover point was originally chose. It would not have been my choice in a
> piano of this size. I do know we weren't going to change it during the
> redesign.
>
> To some extent there will be similarities in the design of pianos of similar
> size because of the dictates of what has been considered 'good scaling.'
> There is also a great deal of copying going on so that the mistakes of one
> design get passed on along with its strengths. In small scales this has
> mostly been mistakes. I don't know of any 'good' scale designs (in my
> opinion, of course) currently being produced in small pianos, either small
> verticals (say below 115 cm, or 45+ inches) or small grands (say shorter
> than 160 cm, or 5' 3"). .
>
> And who ever said -- more properly, who ever proved, that E-20/F-21 was the
> best place to cross over on a large scale such as those typically found in
> our so-called concert pianos of today? (So-called because a piano of any
> size used in a concert becomes a concert piano. Some of the most enjoyable
> concerts I have attended used pianos in the 200 to 225 cm (6' 7" to 7' 5")
> range and were performed in halls seating only 200 to 250 people.)
>
> Del