compression waves

[Ron Nossaman]

>Ron mentioned that Harold's patent uses a correction factor of 1.5% (Ron
>please confirm that figure), as compared to my set up with factor about 
>8%. To test this I tried a different termination system, clamping the 
>wire between two metal washers. Correction factor is reduced to between 0 
>and 2%, i.e. observed frequencies are much closer to theoretical. 
>Ron, what kind of terminations did Harold use in the patent data (when he 
>determined the 1.5% factor)? 

He didn't give a percentage. He gave 1.26 inches as the length correction
factor of one particular setup he used. He gives no speaking length
relating to that 1.26", instead saying that this figure remained pretty
constant over a large portion of the scale. He also said that this changes
with wire and termination type, so it must be established by direct
measurement for the particular string and termination arrangement being
used. Try a different speaking length that isn't a partial of the original
and see if the correction factor is constant or proportional or....


>Obviously the result is sensitive to the impedance of the termination
>points, but not to the rigidity of the structure. Next would be to 
>selectively adjust the impedance of the termination and monitor the 
>effect on frequencies at a fixed length.

Except that in a piano, the impedance of the termination is affected by the
rigidity of the structure, with the bridge mounted on a soundboard, rather
than a plate. Of course the plate isn't rigid either, but hopefully more so
than the soundboard.


>Incidentally, I did notice very strong excitation in the short undamped 
>section when the length coincided with the 2nd longitudinal partial for 
>the long section. 
>
>Stephen

This is more like what his was about in the first place. What type of
bridge configuration are you using, and how solidly is it clamped to the
beam? Also, what results did you get with that back scale section length as
a partial of the speaking length (not longitudinal frequency), since this
addresses the original claim.

Ron N