[pianotech] Bridge agraffes FYI

[Ron Nossaman]

On 10/26/2012 8:06 AM, Jim Ialeggio wrote:
> Ron O said:
>
> <Indeed, and the lower bridge root height would tend to allow the board
> more flexibility over its speaking area, which would lower impedance and
> would allow for something of a more distorted tone, ie. honking tone.
> Lack of board stiffness would seem to be one of the most commonly
> overlooked factors, when it comes to tone building.

It's about 06:30 Saturday morning for Ron, so he might be a while yet.


> I wonder then...Fast forward to the current Phoenix system. The bridge
> height reduction/stiffness problem, at least in a retrofit, has to be
> present since there is maybe a little room to raise the plate, but not
> 10mm or whatever the height of a Phoenix aggrafe is...no?  If this is
> so, meaning retrofit Phoenix agraffe bridge height is reduced and the
> stiffness/load contributed by the bridge is reduced, does the fact that
> these agraffes function with zero bearing change the calculus of overall
> board impedance?

A typically bridge pinning system will function at zero bearing too, but 
neither necessarily has to in order to work. Add some ribs, and you can 
somewhat compensate for bridge height in a retrofit.

Loading and compressing crown with bearing makes a soundboard assembly 
stiffer without adding weight, but if it can be built stiff enough, 
bearing isn't necessary.

Ron N