Untapered Soundboard Ribs

[Farrell]

The Mehlin grand I worked on the other day had untapered ribs on its soundboard. Ribs on other pianos are somewhat abruptly tapered near the ends. Is that so the panel will tend to move as one unit and flex around the perimeter - somewhat like a speaker cone might move with its firm cone and soft surround material that connects the cone to the basket (I kinda don't think this is really a good analogy). It would seem to me that untapered ribs are quite a departure from "the proper way to build a soundboard".

If soundboards vibrate their various frequencies in small random (seemingly) areas of the board, why do we taper ribs like we do (the abrupt taper near the end). Why not an even taper along the entire rib? Or no taper?

The piano seemed to sound OK, but it was so old and worn that it was hard to get a real good feel for it.

Any thoughts on untapered ribs - or tapering in general?

Terry Farrell