Single Treble Bridge

[Delwin D Fandrich]

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."