[pianotech] What is bloom,

[David Love]

Are we mixing up our terms?  It's gone back and forth and is becoming hard
to keep track so for clarification I'll call the JD damper phenomenon
"bloom" and "swell" the effect following hammer string contact.  Anyway,
that's how I'll comment on it.

You're right that swell can be affected by voicing.  But that doesn't mean
that some pianos don't exhibit a greater amount of that capacity which might
then be optimized by voicing.  A quality also found in these types of pianos
that seem to have this quality optimized is their relative sensitivity to
energy input, meaning that the soundboard is set in motion easily but not in
the same way that a weak and flabby soundboard moves initially.  Rather
there is some combination of light and easy to move but maximized potential
energy in the form of compression which also has the right kind of impedance
to control the way the energy dissipates.  It may well be a fairly small
target that achieves some perfect balance of those factors.

That may relate to the JD effect (bloom as I'm calling it) in that this same
optimized system might respond very easily to the energy input that begins
when you lift the dampers and the soundboard energy starts to recycle via
the previously damped strings.  It's quite possible that there is some
threshold that needs to be crossed in order for that relatively small input
of energy in the JD effect to become noticeable.  

I still lean toward the idea of the amount potential energy in the
soundboard system created by spring compression and some finely tuned (so to
speak) balance between that and the freedom with which the system can be set
in motion.  When those two are optimized you get the most bang for your
buck. 

Hopefully someone can give me a more accurate physical description of what
it is I'm trying to describe.  


David Love
www.davidlovepianos.com


-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Ron Nossaman
Sent: Saturday, March 19, 2011 9:37 AM
To: pianotech at ptg.org
Subject: Re: [pianotech] What is bloom,

On 3/19/2011 10:17 AM, David Love wrote:
> I'm not so sure about that. Are you?  If so, why?

Bloom, given minimal soundboard function and a workable set of hammers, 
is adjustable to some degree by voicing. How much? Given the vague 
definition of bloom, everything is arguable, but whatever passes for 
bloom can be changed to some detectable degree, for better or worse, by 
voicing.

Given the same minimal soundboard function and workable hammers, how 
does voicing affect swell, when the hammers aren't involved in most of 
it? Among pianos I've heard and voiced that exhibited what I'd call 
something like bloom, very few will show the swell effect.

As I said earlier, I wonder how many of the people on list have ever 
heard the swell effect at all. It's quite different from everything 
we're used to.

Ron N