[pianotech] What is bloom,

[David Andersen]

Fantastic. Thank you, Nick---my favorite brainiac hipster. Beautifully simple explanation.

Bloom is what I have listened to in thousands of grand pianos; plucking strings is one the most most revealing diagnostic tests I have developed over the years. Bloom manifests differently in each section of the instrument, and you can develop aural guidelines as you become experienced, based on listening to the gently plucked notes in each section. If some of you really want me to describe what I hear on a piano with a high-functioning board when I pluck the strings in different sections I will; if you can wait 'til June, come to my "Ultimate Tool" class in Kansas City and I'll show you, which is a thousand times easier than telling you. I'll film it as well.....

A significant part of my restoration income here in California is doing rebuilds over a 50-, 60-, or 70-year-old board, so imagine my dread and avoidance of building over a board that turns out to be less than functional; I must test vintage boards very, very closely to determine whether they will function efficiently for the next 50 years. If my rebuilt vintage-board pianos stay in a stable RH environment, they will thrive. If they move into nastier weather, I void my warranty and offer dire warnings unless they are wrapped in a complete Dampp-Chaser micro-environment.

DA




On Mar 17, 2011, at 9:07 AM, Nicholas Gravagne wrote:

> 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