[CAUT] Baldwin SD

[Fred Sturm]

On Apr 2, 2006, at 5:40 PM, Ron Nossaman wrote:
> Hi Fred,
> A quick and dirty non-destructive diagnostic. If the mass of the  
> vise grip added to the bridge clears up or even changes the noise,  
> the noise wasn't the agraffe, string, bridge notching, bridge pins,  
> string level, loose screws, casters, phase of the moon, or evil  
> spirits. It's because the soundboard impedance is too low there. We  
> still have no idea if there is any crown at the spot where the  
> noise is, which would help with the diagnosis as well.
>
> Ron N

Hi Ron,
	Yes, I got the mass and impedance thing, ie, that the vice grips  
would add such, which presumably the SB was lacking, at least in that  
area. I guess I'm trying to get at what "being a goner" might mean.  
What would be the condition of the SB that this trick would diagnose?  
I also wonder why attaching mass (to the underside) wouldn't "cure"  
the problem, if attaching the grips really cleared up the tone.
	Is it a matter of "stiffness" (which can mean DB, spongy wood, lack  
of firm support from rim, a few scenarios)?
	"We have no idea if there was any crown." That's always been a bit  
of a puzzler for me in practical terms, since only a minority of the  
pianos I come in contact with have more than minimum crown anywhere.  
Most are flat with a couple areas of a bit of crown. And yet I  
wouldn't describe them as "goners" by any means. I haven't been able  
to match crown with tonal production out here in what I think Guy  
liked to call Fort Stinkin Desert. Any thoughts on this?
Regards,
Fred Sturm
University of New Mexico
fssturm at unm.edu