Duplicity on a Grand Scale

[Richard Moody]

----------
> From: Michael Jorgensen <Michael.Jorgensen@cmich.edu>
> To: pianotech@ptg.org
> Subject: Re: Duplicity on a Grand Scale
> Date: Wednesday, March 10, 1999 6:29 AM
> 
> Ron,
>     That is pretty interesting. I wonder if various confugurations of
> duplex (i.e angle and length) result also in a change in timber of the
> tone which bleeds across.  
> -Mike
> 
>   
> 
>   Ron Nossaman wrote:
> > 
> > Hi gang,
> > 
>
> > Then, still holding the key down, I plucked the duplex and the
speaking
> > length sounded at the fundamental. Cool! Proof positive that string
energy
> > bleeds past the v-bar to the next segment. 

. What do you suppose
> > happens at the agraffes? I then went down to the tenor section and
plucked
> > the, roughly, 10 mm long segment between the understring felt and the
> > agraffe. The speaking length sounded the fundamental.  The
> > bearing angle here was much steeper than in the treble ( about 20
degrees),
> > and the segment was super short and muted by cloth, and the brass of
the
> > agraffe was much softer than the v-bar, but it still worked. What the
heck,
> > I thought, let's try the bass. Yep, same thing, in spite of the even
steeper
> > bearing angle through the agraffe.
> > 
> > Later, I tuned a new console.  I've got to try the bass too. Key down,
I
> > plucked the segment between the upper bearing pin and the tuning pin
and the
> > speaking length didn't sound like anything I could identify because
the
> > segment I plucked drowned it out and turned the combined sounds into
> > garbage.
> > 
> >  Ron

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.  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