[pianotech] What is bloom,

[Nicholas Gravagne]

David and Dale,

Excellent thoughts. True as ever, these are indeed the underpinnings
of "bloom".

Still, it has been my sense that "bloom", if we had to force a
definition on the term, has been suggested to me over time both
explicitly and implicitly as a swelling of the tone/s beyond what
should seem to be expected or even possible. The tonal envelope seems
to blossom or flourish or "take off" from its sedentary beginnings of
equilibrium.

A satisfactory golf stroke or baseball stroke (JD, baseball thrives in
a small way on your "Green and Pleasant land" ) yields to the golfer
or batsman a sense of "bloom" in that the ball seems to be sailing far
beyond the effort required to send it aloft. Conversely, less than
satisfactory strokes are always disappointing, even painful should you
stroke a baseball at the end of the bat rather than within its "sweet
spot". A big effort with little payback.

Technically, some bloom can be traced to the string vibrations as
these activate the bridge. These vibrations begin orthogonally (up and
down, right angles to the bridge), but give way to rotational
vibratory action. Within this scheme a horizontal vibrational mode
runs into an impedance brick wall of a relatively infinitely high
value where the sustain characteristic of the mode really kicks in,
provided it has something to work with.

When the tonal attack mode of the envelope is sufficiently strong and
powerful and focused, the bridging of the first power mode to the
later sideways vibratory string action and high impedance mode is
relatively seamless and will cause a sense of blossom or bloom. But
should the upfront attack and first power mode be insufficient or
missing, the bridging effect is less obvious or satisfying.

Given this sense of things, all decent pianos have some bloom. But the
best of the lot have it more so. Bloom to some may simply be defined
as very fine piano tone, and not necessarily anything beyond that.
Certainly not magic.

Voicing plays a big role here as well, but that's another story.

In a lab environment, this phenomena should be measurable.

JD's experience with playing chords and then lifting dampers at the
pedal, although related to the above, is different in that the vast
majority of damped strings are suddenly activated through mechanical
coupling and sympathetic vibration upon lifting the dampers.

FWIW

Nick Gravagne, RPT
AST Mechanical Engineering