Increasing Crown

[David Nereson]

   This sounds similar to the last resort attempt at "re-crowning" old 
boards using the automotive valve spring method, where L-brackets are 
fastened to the back posts (or beams) and valve springs press on a slat 
of hardwood which rests on the ribs.  There is an adjusting bolt to 
increase the compression of the valve springs, thereby pushing the 
soundboard outwards.  I've seen and heard this done to mostly school 
studio uprights and it did help.  I tried it on an old upright which had 
a board with only one crack, still some crown, but an annoying buzz.  
The valve springs got rid of the buzz, but the tone and sustain were not 
helpeed any.  A Steinway owner asked me if the same thing could be done 
to increase the sustain and or volume in octaves 6 and 7 of his model B 
(after I had already exhausted my bag of regulating and voicing 
tricks).  I was reluctant to do this to a Steinway but he was willing to 
try anything.   It didn't help.  So we tried adding brass weights to the 
underside of the bridge.  No noticeable results there, either.   
    So, yeah, you can try it, but don't have high hopes.  I realize 
these above-mentioned attempts don't include gluing any laminates to 
ribs.  The springs are held in place by their own compression,  resting 
on fender washers bolted to the adjusting bolts, which in turn are 
bolted to the L-brackets fastened to the back posts.  The other end of 
the spring rests on the slat which is held against the ribs by the 
spring pressure.
    By the way, John Bloch in Denver got the idea of doing this from 
Johnny Pullano, long-time tuner for the Denver Public Schools.  He's the 
one who gave the technical at a PTG meeting at John Bloch's shop.   It 
has a dramatic effect on some pianos and none on others.
        --David Nereson, RPT, Denver