[pianotech] What is bloom,

[Delwin D Fandrich]

It's that "swelling of the tone" that I have a problem with. Your
explanation nicely accounts for the change in the rate of decay that pianos
exhibit following the initial chaotic attack but I fail to see where any
extra energy is coming from to "swell the tone." It is this "swelling" that
I have not seen measured.

ddf

Delwin D Fandrich
Piano Design & Fabrication
6939 Foothill Court SW, Olympia, Washington 98512 USA
Phone  360.736.7563 — Cell  360.388.6525
del at fandrichpiano.com — ddfandrich at gmail.com


-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Nicholas Gravagne
Sent: Thursday, March 17, 2011 9:07 AM
To: pianotech at ptg.org
Subject: Re: [pianotech] What is 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.

...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.