THUD

[David Ilvedson, RPT]

I think I would try some juice to beef up the tone.  

David I.

-----Original Message-----
From: John D. Chapman <chapmajd@wfu.edu>
To: caut@ptg.org <caut@ptg.org>
Date: Saturday, December 02, 2000 5:38 PM
Subject: Re: THUD


>Remember THUD?
>Here is the history.  I had not seen this piano until last month.
>While tuning I noticed that notes 50, 51, 52, and 53 (top four notes in
>agraff section,  just below the treble break) had an unpleasant
>knock/slap sound, the same percussive knock which is in the background of
>all piano tone, but in notes 50-53 it dominates the tone.  These are the
>four notes between A440 and the treble break.  The orchestra conductor
>asked me if I had noticed those four notes, as did the pianist, so I knew
>it wasn't just my imagination. I have checked it out both upstage and back
>stage (wood floors), and back at the dealership (concrete floor).
>        Here is what we have done so far:
>1.  checked hammers for loose glue joint, flange pinning, and screw
>tightness,
>2.  visually checked the action frame joints between notes #53 & #54,
>3.  checked the wippens for sufficient felt at the front to keep the
>jack from slamming into the rep lever,
>4.  checked key frame bedding, front, back, and glides, with and without
>damper pedal, and with and without shift pedal,
>5.  pressed down the back key frame with a long screwdriver to see if it
>was slapping up against the dag,
>6.  played notes with dampers held all the way up by hand and by pedal,
>7.  moved the action in and out to see if the tone improved,
>8.  switched some hammers from the octave below to see if it could be the
>hammers,
>9.  switched some whippins from the octave below to see if it coulb be the
>whippins,
>10.  seated the strings,
>11.  applied firm pressure on the bridge cap at the end of the section to
>see if there was a loose glue joint between cap and bridge body,
>12.  checked for clearance between the bridge and the plate,
>13.  checked for loose ribs,
>14.  checked for clearance between nose and bell bolts and soundboard,
>15.  checked that the bell bolt nut which was one turn past finger tight,
>16.  checked for foreign object lodged between soundboard and frame, and
>between soundboard and plate,
>17.  tightened the end screws of the diagonal plate bar, which could be
>turned another half turn to snug,
>18.  checked key leads and underlever leads,
>19.  checked the key bed with a straightedge front to back.  I found that
>the board just beyond the board on which the balance rail glides rest was
>high.  Chalked it where it passes under the front to back board of the key
>frame which is just under notes 50-53 and found that is was just barely
>touching. Sanded key frame there until there was adequate clearance.
>Playing the note by pushing up on the whippin from underneath with my 
>finger without moving the key still produces the THUD, so I guess that 
>eliminates the keyframe anyway.  
>
>None of this has changed the THUD.  
>What have I missed?  
>Why these four consecutive notes  with no sign of the problem above or
>below them? 
>
>John Chapman RPT
>Wake Forest University
>Winston-Salem NC
>
>