[pianotech] What is bloom,

[Ron Nossaman]

On 3/19/2011 5:41 PM, Alan Forsyth wrote:
> *You guys are making all this sound so complicated to the point of
> confusion. *

That's exactly what I've been trying to avoid, starting with the 
differentiation between what I've always heard called bloom in voicing, 
and this seldom heard swell effect.

What we're talking about here is swell.

> *I'm sure it is something very simple; like the sheer physical act of
> releasing the pressure of all that weight of the dampers against the
> strings and thus the soundboard and allowing the soundboard to do it's
> job properly. In all probability it only occurs on a piano with very
> little downbearing pressure to begin with.*

The piano in my shop I first heard the effect in had from around 0.3° in 
the bass, to just over 1.5° in the treble. Somewhat more than very 
little downbearing pressure. It did have very little panel compression, 
and a lighter rib scale than I use now, so the board was very easily 
driven.


> **
> *As for the swell effect itself, I have experienced it in a different
> context but can only describe it as what I would call a "secondary wave"
> if that makes sense to anybody.*

Yes, that's not a bad description.
Ron N