[CAUT] Sostenuto

[Fred Sturm]

On Dec 30, 2008, at 11:53 AM, Ed Sutton wrote:

> Fred,
>
> So, to hedge your bets, you would set the dampers to lift as early  
> as acceptable on the key, then set the damper pedal to stop lifting  
> as low as possible, i.e. make the difference as great as possible  
> between key and pedal lift. Then set the sostenuto to catch as high  
> as possible, when the key is fully depressed, and not very far in  
> toward the belly rail. Thus, hopefully minimizing the snapping tabs  
> when the sostenuto is released, and also minimizing the chance of  
> accidentally catching all the tabs when the damper pedal is depressed.
>
> This would work, unless there is a requirement to catch all dampers  
> with the sostenuto when the damper pedal is pressed.
>
> (Am I repeating something someone already wrote?)
>
> Ed


	Hmmm, I think this would create other problems. When you need to do  
quick changes of sostenuto, it seems to me you want the blade to catch  
the tabs as low as possible. You don't want to have to think of  
keeping the keys in their bottoming out position for the period of  
time needed to catch the tabs (ie, the time it takes to depress the  
pedal fully). Better the blade should be able to catch during a range  
of motion of the keys (approaching bottom, through bottom, and a  
little upward motion at the keytop). The hands and fingers are often  
moving fast, so you want some forgiveness in the system, you don't  
want to have to do an unnatural stop of motion.
	Yes, I think dampers should lift a bit early with the key for best  
sostenuto action. I think that 1/3 keydip works well as a damper lift  
point, which is usually a wee bit before the hammer has moved half way  
to the string. And I think the sostenuto blade should be set about as  
close as possible above and in front of the tabs, _just_ enough for  
clearance (and a fudge factor for safety). For my taste, anyway. This  
means you can actually catch the tabs before the hammer sounds, at  
least conceivably.
	I have played on pianos where the rod was set high and found that  
using the sostenuto was next to impossible under those conditions,  
very unreliable: made me have to do almost a stop action to be sure of  
catching the dampers. I guess part of it is that one doesn't always  
bottom out keys when playing, especially in rapid passage work. One  
sets them moving, and then moves on to other keys before the first one  
has sounded.
	Also, if the blade is set with too much gap from the tabs (away from  
the belly rail), it will only catch them securely when the pedal is  
fully depressed, which is another unforgiving thing: you have to be  
sure that the key is bottomed at the instant the pedal is bottomed.
	Having things closer means you can catch the tabs with a lot more  
slop, less utter precision of timing between fingers and feet. I think  
that is probably the most comfortable and secure feeling situation.
	I don't think we should regulate to try to minimize return slap of  
tabs. Better to spend the time educating pianists.
Regards,
Fred Sturm
University of New Mexico
fssturm at unm.edu