Impedance problem

David Love davidlovepianos@comcast.net
Thu, 20 Jan 2005 19:57:44 -0800


(I guess those were vise grips, not vice grips)

David Love
davidlovepianos@comcast.net 

-----Original Message-----
From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On
Behalf Of David Love
Sent: Thursday, January 20, 2005 7:55 PM
To: 'Pianotech'
Subject: Impedance problem

I ran into an interesting phenomenon today.  Rebuilt Steinway A c1915.
New soundboard.  Reasonably poor job but that's not the issue.  Note E5
was extremely loud compared to its neighbor F5.  Switched hammers and E5
was still very much louder.  So a clamped a set of vice grips onto the
rear bridge pins at E5.  Sure enough, the addition of some mass caused
the loudness to diminish and the sustain to be slightly enhanced.  The
customer thought so too.  I was surprised that the addition of mass
would produce an effect so localized without having an appreciable
effect on F5.  Was I hearing things?  Well clearly I wasn't, but what
was going on underneath or in the panel that there would be such an
effect right at that point.  Thinking about it later it occurred to me
that rib position under the bridge at that point might have had an
influence.  Comments?

David Love
davidlovepianos@comcast.net 



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