Soundboard mass

[David Love]

No I haven't built one of those...yet.  Do you think that an argument can be
made, then, for using a heavier wood than spruce for the ribbing in the
treble section?

David Love
davidlovepianos at comcast.net 
www.davidlovepianos.com

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Ron Nossaman
Sent: Monday, November 26, 2007 3:04 PM
To: Pianotech List
Subject: Re: Soundboard mass



> So would you say that the danger in adding the fish to reduce the area of
> the SB in the treble would be extra stiffness but reduced mass?  And what
> would constitute a light bridge?
> 
> David Love

You haven't apparently built a too stiff treble yet. it 
*screams* - wild, woolly, and very nasty! And the sustain is 
very short. Added mass brings the board's resonant frequency 
down and it gets sweet, clean, and long. That's why I over 
build with the intention of mass loading the treble. It's a 
whole lot easier to bring into function by adding mass to a 
too stiff assembly than it is to stiffen a too flexible one at 
the top end.

A light bridge would be short, narrow, or have holes drilled 
in it. Those short bridges in the Steinway trebles contribute 
to the already problematic likelihood of getting a CC assembly 
stiff enough up there, especially with the panel thinned at 
the edges! Low mass doesn't show up as a problem in the treble 
until you get beyond a certain stiffness. That's why I said I 
thought the short bridge was a stiffness, rather than a mass 
problem earlier.

Ron N