Strange bridge in a Steinway

[Ron Nossaman]

At 06:08 AM 7/13/2003, Terry wrote:
>And why, on some models, do they have a continuous bridge root between the 
>tenor end of the long bridge and the bottom end of the bass bridge? It 
>seems this would only serve to increase stiffness in this area.

It does, and couples the mass of the bass strings to the low tenor bridge. 
It's attempted compensation for a soundboard assembly with too low 
impedance in the low tenor. The tradeoff is that it restricts the low bass 
in the process. Better to have left the bridges separate and build a 
soundboard that doesn't need crippling of the bass to salvage the low tenor.


>Now I wonder if there is a design out there that has the tenor cutouts AND 
>the connector between the two bridges?

Steinway models B and D, in current production.


>Perhaps that would serve to complete the "circle of sound" without making 
>things too stiff in that area? We throw that phrase around so much, I 
>don't even really know its origin - was it part of a manufacturer's 
>marketing campaign?
>
>Terry Farrell

Yes, I think so. Bill Garlick gave me hell for suggesting plate bushings in 
Steinways because it disrupted the Circle of Sound. The Sound is supposed 
to go from the strings to the bridges to the soundboard to the rim to the 
beams to the Tone Collector to the plate horn to the pinblock to the tuning 
pins to the strings. I asked how that worked with nearly all of the pins 
leaning on the plate, and how that sound got past that understring cloth 
and the agraffes (ignoring everything else), and the subject promptly moved 
on to something else.


>----- Original Message -----
>From: "Calin Tantareanu" <dnu@fx.ro>
> > Thanks to all who responded. The idea to reduce stfiffness makes pretty 
> good
> > sense, but I wonder if normally the long bridge is too stiff for that area
> > of the board without the cutouts?

In a whole lot (most?) of the pianos I tune, that area is already too 
flexible, and it doesn't have a thing to do with the stiffness of the 
bridge. It's the stiffness and mass of the assembly that makes the 
difference. Low impedance (in the low tenor) soundboard assembly and poor 
scaling are the primary reasons for those lousy sounding tubby low tenors 
we fight every day.


> > And if more flexibility is needed for the end of the long bridge, what 
> about
> > the bass bridge?
> > That one is normally taller = stiffer (this is probably compensated by it's
> > short length) and sits in most pianos closer to the rim than the end of the
> > long bridge. Why not make the bass bridge more flexible too?
> >
> >  Calin Tantareanu

That's part of the problem and challenge of soundboard design. The low end 
of the bass bridge is very close (in proximity on the board) to the low end 
of the tenor bridge, yet they have considerably different soundboard 
impedance requirements. The low bass needs lots of flexibility (usually 
more than is available to it), and the low tenor needs more stiffness 
(usually more than is available to it).

Ron N