Predictability of Compression Crowning: was Soundboard stiffness variances

[David Love]

Rarely do we have opportunities to compare two identical pianos side by side
to see how they have faired over time but today I again visited a long time
customer of mine who owns two Hamburg Bs.  Both were purchased new in
Germany at the same time (mid 1980s), the pianos are about 800 serial
numbers apart.  Both were shipped together to San Francisco where they have
lived ever since side by side in the same room.  Tuning them today and in
view of this conversation we have been having I was struck (as I always am)
by the differences between the two.  Visually, one of the boards is riddled
with pressure ridges while the other one is not.  The one with the pressure
ridges exhibits serious killer octave problems and a strong percussive
quality with notable distortion and diminished sustain through the tenor
section.  The other one has some killer octave problems as well though not
quite as serious.  The tenor section is quite full and round, little
distortion, nice sustain.  The bass on both pianos is fine.  It is
interesting to note that when the customer purchased the pianos, he was
looking for two instruments that were a close match tonally.  Since I wasn't
there at the time of the selection I can't speak to whether he in reality
was able to do that, but he certainly thought he did.  I would say that
there is no mistaking the fact now that the pianos are quite far apart in
their tonal response.  

I would guess that the Hamburg Steinway factory goes to great lengths--as
much as anyone--to control the EMC at glue up.  While I agree this is
anecdotal and doesn't constitute a comprehensive study, it does speak to the
issue of variability in panel response to compression style crowning and/or
the difficulty in environmental control during manufacturing.  If I am not
mistaken, these boards are hybrids and have crowned ribs as well suggesting
that while, presumably, there is less reliance on panel compression, one
still can't escape it in this particular method. 

David Love
davidlovepianos at comcast.net
www.davidlovepianos.com