Single Treble Bridge

[Doug Richards]

Del,

You wouldn't happen to have an outline of a medium sized sound board and
bridge in electronic format would you?
Don't know if you saw my post yesterday, but I'm doing some modeling on
string inharmonicity.  Some time in the future, I'll be wanting to add a
soundboard with bridge and look at string tail length/angle, soundboard mode
shapes and stuff like that.
Anyway, if you have a file available (dwg, mi or dxf) it sure would save me
a bunch time measuring...

doug richards
San Jose, CA

> -----Original Message-----
> From:	Delwin D Fandrich [SMTP:pianobuilders@olynet.com]
> Sent:	Friday, August 28, 1998 10:47 AM
> To:	pianotech@ptg.org
> Subject:	Re: Single Treble Bridge
> 
> 
> 
> Tom Cole wrote:
> 
> > Del,
> >
> > You discussed, in a recent post, the need for a separate tenor bridge
> > for wound strings and that the speaking lengths should be an extension
> > of the bass section. It occurred to me today that Steinway tried that
> > over 100 years ago and abandoned the idea. I also have heard of someone
> > who has converted the early model As to a single treble bridge design,
> > saying that it's an improvement.
> >
> > So I'm confused and would like to hear your opinions on this conundrum.
> >
> > Tom
> 
> --------------------------------------------------
> 
> Tom,
> 
> Over the years Steinway has abandoned a lot of good design ideas while
> clinging
> tenaciously to a few bad ones.  Obviously, Steinway builds some excellent
> pianos, but they are certainly not the last word in piano design.  Nor am
> I.
> Nor is anyone else that I know of.  So, with that in mind...
> 
> Not all of the ideas that were tried out and abandoned 100 years ago --
> whether
> by Steinway or by anyone else -- were bad ideas.  Sometimes ideas came
> along
> before their time and had to wait for appropriate materials to come along.
> Sometimes manufacturing technology was not developed adequately to take
> full
> advantage of an idea.  Other times a good idea was simply executed poorly.
> This
> was the case with the short bridge on the three-bridge Model A.  I'm
> assuming
> this is the piano you're referring to in your post.
> 
> There were three problems with this specific design:
>     1)  The string lengths in the short bridge section were too short.  I
> assume
> this was done so that tri-chord wrapped strings could be used.  This, of
> course,
> was the second problem.
>     2)  Tri-chord wrapped strings were used.  I have yet to see a scale
> using
> tri-chord wrapped strings that I really liked.
>     3)  The soundboard and ribs did not acoustically tie the three
> separate
> sections together.  In part this was a consequence of the
> compression-crowned
> soundboard design.  It is very difficult -- nearly impossible -- to alter
> the
> elasticity characteristics of a compression-crowned soundboard to
> adequately
> blend the several disparate sections of the scale together.
> 
> There are some real problems trying to redesign things like this on an
> existing
> piano.  I am also interested in loudspeaker design.  The bass/tenor
> transition
> of the piano scale is much like the crossover design between a woofer and
> a
> mid-range speaker -- fairly simple in concept, much more difficult in
> actual
> practice.  We struggle with these issues every day since nearly every
> piano that
> comes to our shop is sent here for some level of redesign along with its
> remanufacture.  We are limited by the original string scale layout --
> i.e.,
> action center spacing and their sweep -- and the original configuration of
> the
> plate.
> 
> In the case of the three-bridge Model A, the compass of the bass section
> should
> have been much greater.  In a piano of this size the bass section should
> encompass at least 27 notes (instead of 20).  The short tri-chord steel
> strings
> often found at the low end of the tenor bridge have a tubby tone that
> simply
> cannot be voiced out with hammer work.  Even then there should have been a
> few
> unisons of wrapped bi-chords terminated on a separate bridge on the tenor
> side
> of the bass/tenor plate break.  Done properly, this short bridge could --
> and
> probably should -- have been tied into the long tenor bridge.
> 
> I have also worked with the idea of a single treble bridge on these
> scales, but
> I'd not go so far as to call them much of an improvement.  They were,
> perhaps,
> less bad.  The real improvement comes with a new short bridge using
> properly
> scaled bi-chord wrapped strings.  Along with a soundboard and rib system
> designed to bring the three separate sections -- the low end of the long
> tenor
> bridge, the short cross-over bridge and the high end of the bass bridge --
> together.  Even then, there remains a serious discontinuity between the
> lengths
> of the low tenor strings and the upper bass strings that cannot be
> corrected
> without building a new plate.
> 
> It is really much easier to start with a clean computer screen and design
> the
> thing from scratch.  When doing this all of the various factors can be
> balanced
> out much more easily.  Much has been learned about piano design in the
> past 100
> years.  It's just that little of this knowledge has been incorporated into
> the
> pianos of today.
> 
> Rather than answer your question, I've probably just posed a bunch of new
> ones.
> Such is life.  Isn't it wonderful?
> 
> Regards,
> 
> Del
> 
> "If it ain't broke -- break it.  Then build it better."