Soundboard Evaluation

[David Love]

If the board has crown but there is no downbearing, doesn't that suggest the 
plate is in the wrong place?  If the upper part of the board has no pressure 
on it, then it will sound weak.  There should be progressive bearing from 
bottom to top with the bass set minimally or even at zero.  Of course, 
without taking down the tension you don't know if the board has no pressure 
on it or if it has flattened out under pressure?  I think you will have to 
take the tension off the board to see if the bearing was actually set at 
zero or if the board is collapsing under tension.  Measure the bridge height 
relative to the struts, take the tension off and see if the distance 
changes.  If it doesn't, I would consider resetting the plate height if it 
doesn't create problems with clearence for the action.  Otherwise, you will 
have to deteremine whether it is worth the cost of putting in a new board.

David Love

>From: "Farrell" <mfarrel2@tampabay.rr.com>
>Reply-To: pianotech@ptg.org
>To: <pianotech@ptg.org>
>Subject: Soundboard Evaluation
>Date: Thu, 14 Jun 2001 22:51:26 -0400
>
>Looking for a second (or third!) opinion on a soundboard. This is the 5' 4"
>Knabe grand that I just finished installing a keybed in. I just flipped it
>over and put the action in (it actually fit in - yeaaaa!). Piano sounds a
>bit weak and has a bad killer octave area. I measured for downbearing with
>the goofy little three point brass thingee. Absolutely ZERO downbearing on
>the whole long bridge. Everywhere. Zero. Never saw that before. A little 
>bit
>of bearing on the bass bridge. Checked for crown with the string. Excellent
>even 3/32" crown roughly centered under long bridge for the two tenor
>sections, about 1/16" to 1/32" crown for the lower part of the treble
>section, and zero crown for the upper treble section (exactly where the
>killer octave area starts!) and the high treble section.
>
>I'm gonna have one more go with the owner (a hospital - my guy who makes 
>the
>piano decisions is the dude you call to have a light bulb changed or if you
>get stuck in the elevator) about rebuilding. I need to decide how heavily I
>am going to push a new soundboard. The board has no cracks. I had to glue
>the tenor end of the long bridge back to the soundboard a few year ago
>because it was buzzing.
>
>I clearly feel a new soundboard is needed to bring the piano up to its
>potential. But, playing devil's advocate, most of the board has good crown 
>-
>why not just recap the bridges and put in appropriate downbearing - 
>although
>admittedly this would be tough in the high treble where there is already a
>flat board - although hard to measure the little bit of crown that
>would/should be there.
>
>I say if the plate is coming out for new bridge caps, give it a new board
>also - otherwise they will likely have a very lackluster bla piano.
>Waddayasay???
>
>Terry Farrell
>

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