[CAUT] Birkett videos online

Fred Sturm fssturm at unm.edu
Fri Feb 12 08:19:29 MST 2010


On Feb 11, 2010, at 1:08 PM, Adkins, Richard wrote:

> Is it me, or does that left string of  trichord  get out of phase as
> the clip progresses in this clip?
>
> http://real.uwaterloo.ca/~sbirkett/videos/c64%20bridge.avi
>


	To my eye, it looks like a beat. We see the three strings  
synchronized, then going out of phase, until their phases are opposing  
at which point we sometimes seem to see a missing vibration at the  
pins (the strings seem to stop for a moment, about equal in time to  
one of the regular up and downs - this "pause" becomes pronounced late- 
ish in the video), then a repeat of the cycle. But it is pretty  
puzzling, especially as it seems the two bass side strings often  
alternate with the single treble side string. That is, the single  
string seems to stop while the two strings move, and vice versa.
	I think the C64 damper clip was done simultaneously, so there you can  
see the strings out farther, where they have more amplitude. It would  
be nice to be able to see them simultaneously and watch how movements  
by the damper relate to movements by the bridge. Birkett was able to  
do that, but I don't think MPlayer can do two at once. If someone  
knows how, please let me know.
	As always, things like this lead to more questions than they answer.  
Why is that one string so out of phase with the others? Is it tuning?  
Is it mating? Something else? Then you get to wanting to see what  
would happen if you set up the experiment to show, specifically,  
tuning or mating. And with the dampers, to show the difference between  
bass dampers where the wire bears lightly on the bushing compared to  
being set in the middle (as they are in D6 and A14 damper clips).
	In any case, they are fascinating, providing hours of entertainment  
<G>. I think he should get an Oscar.
Regards,
Fred Sturm
University of New Mexico
fssturm at unm.edu





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