[CAUT] Baldwin SD

[Ron Nossaman]

>> 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? 

Low impedance.


>I also 
> wonder why attaching mass (to the underside) wouldn't "cure" the 
> problem, if attaching the grips really cleared up the tone.

If it eliminated the problem, by all means. I'd hesitate to 
call it a cure though, just a temporarily effective band aid. 
I certainly wouldn't buy a piano based on the success of this fix.


>     Is it a matter of "stiffness" (which can mean DB, spongy wood, lack 
> of firm support from rim, a few scenarios)?

Stiffness. Cumulative loss of compression in the panel letting 
the assembly become too flexible. Sometimes, adding mass can 
compensate to some degree (up to a point), but the lack of 
stiffness that caused the problem the weight lessened, is 
still there.


>     "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 tune lots of pianos that sound acceptable to their owners 
when played at the low volume levels at which their owners 
play them. Played at higher levels, such as I apply in tuning, 
they fall apart tonally into really nasty distortion. As long 
as the pianos deliver what their owners need out of them, 
happy day. When the aggressive pianist complains about the 
distortion in the killer octave during those dry winter days, 
the bottom line is that it will likely prove to be the 
soundboard.


>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?

How many nasty sounding killer octaves have you found that had 
both positive crown and positive bearing at the point in the 
scale where the problem is? For that matter, how many times 
have you checked KO bearing and crown when you hear the attack 
distortion there, looking for some relationship between the three?

Ron N