[pianotech] Increasing bridge height

[Will Truitt]

To the best minds of our generation (at least regarding soundboards):

 

I just pulled a two bridge 1909 Steinway 6' 1" A into the shop for a total
soup to nuts rebuild, which will include a new soundboard.  I recall some
discussion in the past on the forum about increasing the bridge height in
Steinways (which some feel is too low) to increase mass and stiffness.
David Love and Ron Nossaman's names come to mind.    I seem to remember talk
of increasing the thickness of the bridge by about 4 mm over the thickness
of the original.  Since I am putting a new board in this piano and will be
setting plate height for global bearing values on adjustable plate bolts as
well as setting downbearing on the bridge cap, I am considering the
possibility of doing this.  I would  bore my hammers to make the appropriate
accommodations there, as needed

 

My questions are:

 

What are the tonal benefits that you feel are derived by increasing the mass
and stiffness of the bridge by increasing the height?

 

Increasing the bridge height will require raising the plate around the rim
with the adjustable plate bolts or dowel system to achieve desired bearing
values.  Are you increasing the thickness of the pinblock by a
corresponding amount to raise that end of the plate too?

 

Since the treble bridge is in effect another rib, albeit one running at
approximately right angles to the other ribs, are you making any
accommodation in the design of the ribs for these changes?

 

Does increasing the plate height require any other accommodations in the
action set up other than boring the hammers for the new string height?

 

I find this idea very intriguing.  Several years ago I sold a 6' 7" Kimball
Viennese Edition grand piano out of my shop for a customer.  While not
having a particularly elegant tone, it had outstanding volume and sustain
throughout, particularly in the treble.  What makes this interesting was the
fact that the  treble bridge heights were 39 to 41 mm. - a pretty tall
bridge.    Obviously this would not be the only thing that contributed to
these tonal qualities, but I cannot help wondering if it were a significant
ingredient.  

 

I look forward to the thoughts of all contributors.

 

Will Truitt

 

 

 

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