Bridge Seating (another footnote)

[Ric Brekne]

Hi folks

Just thought I'd relate an experience I had today.  The recent 
discussion stimulated  to take a few new looks at some of the things we 
do for different reasons and see if perhaps they can relate to this 
subject.  Today and over the last few days I've been adding mass via use 
of a Vice Grips to various parts of the bridge to see what kind of 
effect it has on false beats and related phenomena.  I found the 
following to be quite interesting.

Attaching a 330 gram vice grips to the BACK bridge pin of a note, I 
found a clear effect on the occurrence of false beats.  Most of the time 
the beat for the corresponding unison pretty much disappeared.  Also for 
adjacent unisons there was an impact.  Seemed like there was an impact 
for about a 4-5 inch range around the vice grips.  Another thing that 
happened was that very clean tuned unisons in the same area were often 
in need of retuning after the vice grips were attached. 

I also tried attaching the vice grips to the bridge itself at the break 
between the treble and highest treble and at the end of the bridge at 
C88. In both cases the results were quite similar.

No fancy measuring devices used... just ears... but the results were 
quite noticeable. It would be interesting to put this to some fancy 
bench testing to ascertain more clearly whats going on. But it seems 
evident to me, as it has for quite some time... that it is better to 
view the cause of false beating as a general condition of asymmetric 
admittance from the bridge then it is to simply point at one specific 
condition or another.  Clearly there are several ways of influencing the 
presence or lack thereof of false beats.

Cheers
RicB