Damper Problems

[Ron Nossaman]

At 09:49 AM 5/14/96 -0600, you wrote:
>    Can anyone help me with a damper problem?
>
>    The piano is a 1991 Schafer and Son 4'7" grand.  The first two bi-chord
>    notes in the bass scale (C2 and C#2) continue to sustain after the
>    dampers have settled onto the strings.
>
>    The dampers are in perfect alignment in all dimensions.  There is plenty
>    of damper follow.  There is nothing binding in the back action.  The
>    damper wires move freely through the guide rail.  The felt wedges are
>    rather wide at the point and settle very near the top of the bi-chord
>    strings; however, they look similar to all the other bi-chord wedges.
>    The sustaining sound is definitely coming from C2 and C#2 and is not a
>    sympathetic vibration from somewhere else.  It seems like the dampers
>    are coming down at a node on the strings because the sustaining sound
>    appears to be a partial or harmonic of the fundamental.
>
>    Do I need to needle the damper felt?  Is this a job for damper pliers?
>    Do the dampers require some modification?  Would more weight on the
>    underlever help?  Is this a design flaw the customer must live with?
>    Any help is greatly appreciated!!
>
>    John Piesik
>    San Diego Chapter PTG
>    JPIESIK@ARINC.COM
>

John,

Technical dodge #14,238.01 beta

After you've tried all of the other suggestions, and before adding weight,
try replacing the two damper felts with three smaller pieces. Glue the fore
and aft felts where the old ones were, so they'll look similar from
overhead, and dink around with the placement of the middle one. This often
kills, or at least adequately minimizes, the amazing singing partial without
having to resort to hanging a brick on the underlever. The idea here is to
dodge the node that's causing the problem. If anyone asks about the two
funny looking dampers, "It's not a bug, it's a feature".


 Ron Nossaman