Bridge caps

[Yardarm103669107@AOL.COM]

In a message dated 4/1/2001 10:53:51 AM Central Daylight Time, 
ANRPiano@AOL.COM writes:

<< I would be interested in any research/references relating to this.  I have 
 heard about keeping the pins close to the height of the strings, but never 
 this short.  I have seen everything from the top of the string matching the 
 top of the pin to the pin being 1/8 to 3/16 over the top of the bridge on 
all 
 different quality levels of pianos.
 
 This would make sense if your saying energy bleeds off the top of the pin.  
 Is that what you mean? And do you think this is a significant amount of 
 energy?
 
 Thanks for you input,
 
 Andrew Remillard
  >>

Andrew:
I recently restored a SW L from 1973 (new board! and caps) which, in the 
original, the bridge pins were fully 1/4" -5/16" above the height of the 
bridge plane. It was the ugliest looking and worst sounding SW L I've had the 
privilege to work on. Aside from a lot of other tonal problems, it's I think 
incontrovertible that vibrational energy is lost into the ether from the 
unused portion of the bridge pin; simply hold a brass rod on the tip of a 
bridge pin and listen to the tonal decay change. This is not a simple 
impedance issue as much as an energy efficiency issue. Where do we want the 
given energy to go? I would think as much as possible into the trunk of the 
bridge for transduction into the board and beyond. If that's true, then the 
bridge pin (which should be bottomed out in the trunk of the bridge and not 
mostly in the bridge cap) should be most efficiently transferrring energy by 
not extending any higher than it has to above the bridge. While I can't point 
you to any research on this, I bet there is some; aside from that, there is 
an intuitive correctness to this.
PR-J