Duplicity on a Grand Scale

[Ron Nossaman]

>
>On  two uprights the very short segment between the upper bearing ridge
>and the pressure bar when tapped with  knife blade sounded the fundamental
>loud and clear.  In the bass however this did not work.  I noticed the
>string went over a hump right behind the upper pins.  If this works on a
>grand there the string goes up the "ski slope" over felt it must be
>because of the free segment between the felt and agraff. 

*Yep, that's my call.


> The segments
>behind the bridge don't do this, or not any more than tapping on the
>bridge.
>
>Um... I don't suppose by a fantastic stretch of the imagination that these
>sgements duplexed or not act as sort of a sonic flywheel? That the shock
>of percussion sets these segments vibrating which then feed back into the
>speaking segment? I bet that would keep old Hermann and Theo up all night.
>
>Ric Holtz
> 

* That's probably pretty close to what happens. The rear duplex is supposed
to make noise, just like the front duplex is supposed to make noise. The big
difference is in how the string energy is fed to the duplex segment. It
bleeds straight across the v bar from the speaking length to the front
duplex, but there is no bleed through the bridge into the back duplex. It
gets it's energy second hand, from the moving bridge. I don't really know
why some rear duplexes are *so* noisy and some aren't. For instance, the
back scale in the tenor section of an S&S D, if it's not braided off, groans
like a Banshee with a head cold. The pianos where I've added vertical hitch
pins and deleted the aliquots, don't seem to have any obnoxious noises at
all coming from that back scale. Perhaps the longer length, with the
pivoting action of the termination at the vertical hitch, and the weaker
excitation don't let enough high partials develop at a high enough volume to
be audible. That one's still on the list for playing with.

   
 Ron