Bridge pin spacing (was Baldwin SD-10)

[Tom Servinsky]

Ron,
Thanks for the tutorial.
Tom Servinsky,RPT
----- Original Message -----
From: "Ron Overs" <sec@overspianos.com.au>
To: <pianotech@ptg.org>
Sent: Saturday, September 08, 2001 9:41 PM
Subject: Re: Bridge pin spacing (was Baldwin SD-10)


> >. . I have
> >  >yet come to a conclusion as the "why's" vs. the "how effectives" are
each
> >>design.
> >  >Tom Servinsky,RPT
>
> (thanks for the note in another post about Del's bridge notcher Tom)
>
> Ron N wrote;
>
> >There really isn't a simple answer either. Stiffer and heavier are
> >determined by width and height, like with any beam. The impedance of the
> >soundboard assembly at any point in the scale is determined by the mass
and
> >stiffness of the assembly, as seen by the strings at that point.
>
> Indeed. A wider lower bridge will have higher mass with less
> stiffness, and vice versa.
>
> >Scale tensions, soundboard panel thickness and grain direction, rib
dimensions
> >and placement, rim stiffness and proximity to the bridge will all have
some
> >effect. Like everything else in a piano, everything affects everything
else
> >in some way. Too flexible an assembly, and you get one big killer octave.
> >Too stiff and heavy an assembly, and you get a very quiet piano that
> >sustains for days. Something in the middle, and a considerable range of
> >something at that, is what you want. I've found that I can get enough
> >control of the process to produce the kind of sound I'm looking for with
> >panel and rib design without having to worry too much about bridge cross
> >sections. A couple of years ago, I replaced a 40mm wide bridge with a
30mm
> >wide bridge with a new soundboard and rib scale, and was very pleased
with
> >the result. Since I haven't replaced a bridge with one of different
> >dimensions on the original soundboard, I can't say exactly what would
happen.
> >
> >Ron N
>
> Around 1990 we re-bridged a circ. 1925 US made D with an original 8
> mm crowned sound board. This piano must have been set
> out-of-specification originally since it had almost zero down bearing
> with considerable sound board crown. Since the board looked to be in
> good overall condition, we built new bridges (with a fully revised
> logarithmic-style scale) of original width but 40 mm high (standard
> Steinway D is nominally around 32-34 mm). No other design changes
> were made (speaking length and bass scale revision excepted). The
> result did not sound like a Steinway. It had much longer sustain with
> less initial sound pressure level (but nonetheless was a very
> satisfactory instrument). One local commentator (a tuner of note)
> said that we got rid of the Steinway tone to create something much
> more European in character. This piano was our first re-bridged D
> with a revised scale. The tuning stability adjacent to the plate
> struts was very much improved, since we altered the speaking lengths
> exactly to that calculated to achieve an even graduation of the
> percentage of breaking strain.
>
> The option of building sound board assembly stiffness with rib
> height, as opposed to bridge height is interesting. I suspect that
> bridge rigidity remains an important consideration even when stiffer
> sound board ribs are used to raise the impedance of a board. If tall
> relatively stiff ribs are used with a low height 'floppy' bridge,
> there is I suspect a tendency for inferior note to note sustaining
> qualities (the sustain will tend to be shorter for those notes which
> do not lay over a sound board rib - those long bridges which are
> attached to the sound board only over a rib at the lower end are also
> similarly suspect). I inspected at a new Korean made 'concert' piano
> last year with quite standard sized ribs and a 24 mm low bridge. The
> tone was, how shall I put it, most ordinary and short (most other
> factors seemed to be reasonably satisfactory -  even the
> workmanship). A local contemporary manufacturer also uses 24 mm high
> bridges to create a 9'6" piano which sounds like an instrument from
> 1850 (something akin to speaking with a peg on your nose). If you
> look at the grand pianos from around 1850 they all seem to have lower
> bridges and ribs than contemporary pianos. Both these factors seem to
> contribute to their duck-like tonal qualities. Mind you, when
> listening to these instruments today with their now compression set
> panels, they are sure to sound even more short toned than originally.
>
> As Ron N says, "everything affects everything else in some way". It's
> very useful to think about each individual element and its cause and
> effect on tonal quality. They all come together to produce a result
> of some kind. There are so many combinations of stiffness, mass and
> radiating area which remain to be tested. As long as we can keep an
> open mind about future directions, superior pianos must surely be
> built in the future.
>
> Ron O
> --
> Overs Pianos
> Sydney Australia
> ________________________
>
> Web site: http://www.overspianos.com.au
> Email:     mailto:ron@overspianos.com.au
> ________________________