[pianotech] Tuning the duplex sections

[David Love]

Why would that be a surprise?  If you go to the piano, lift the dampers and
then simply clap your hands over the strings you'll get some excitement of
the strings.  That certainly comes from the change in air pressure that
follows the clapping of your hands.  It only makes sense that the vibrating
strings on the notes played would also produce some excitement of the
strings that are undamped after the initial notes are struck by the same
mechanism.  I would guess that would be true of the backscale lengths as
well.  Though the excitement of the backscale lengths might not in
themselves be audible, once the are moving the energy will then be
transferred to the soundboard via the backside of the bridge.  How audible
that contribution is might be questionable but in theory it should take
place.  It doesn't much matter whether those backscale lengths are plucked,
struck with a hammer, or struck with a change in air pressure, the effect is
the same, it's just a matter of degree.  The front duplex by the same token
probably receives some energy from the changes in air pressure from the
surrounding air.  The difference is that the front scale is not attached
directly to a flexible diaphragm as the soundboard but rather the plate
which is acoustically dead, in effect.  Doesn't that make sense?  

David Love
www.davidlovepianos.com


I had a surprise the other day which I hope to be able to understand 
in due course.  I've mentioned once or twice in the past that the 
sound of certain pianos will blossom and flourish noticeably when all 
the dampers are lifted _after_ the notes have been played and held 
down, and I see this as the sign of rather a special piano that 
allows the player to achieve effects that are impossible with most 
pianos, not possible, let's say, on a Yamaha.  Now I recently a very 
old Kirkman grand which has a very powerful and brilliant sound and 
of which I have high hopes when I get round to restoring it.  The 
piano is up to pitch but nowhere near in tune.  The sustain is 
excellent.  Now the other day in a moment of leisure I climbed over 
all the junk in its way, sat down to play it and tried the pedal 
test, holding down a chord and then lifting all the dampers.  To my 
dismay, instead of the blossoming and flourishing, there was a 
noticeable diminution in the volume of the sound.  Now I'm very 
curious to know what will happen when the piano is tuned.  What do 
you think?

JD