[pianotech] Square grand rebuilding/repair

jim at grandpianosolutions.com jim at grandpianosolutions.com
Mon May 21 20:48:47 MDT 2012


Now, I'm really confused! Did you rescale it to tensions relevant to
425cps? Or, just arbitrarily change the tension scheme? And,..are you going
to tune it to 440cps? If not, then why change the scale. All...most
confusing Jim!


Nah, just poor communication on my part. It takes me time to write 
coherently. Plus I'm working with some design assumptions that might be 
considered a flavor other than vanilla. Lets try again.

It will be tuned to 425.

Set scaling program to 425.  If the wire sizes and core/wrap 
configurations remain unchanged, the 425 will automatically reduce 
tensions a bit, but not a heck of a lot, just a couple of %.

Based on some earlier tension dropping experiments I've been messing 
with in the bass, I wanted to go further than this...simplified bass 
tonal spectrum.  Add to that reasoning the structural reasons for 
wanting more than a couple % reduction in tension.  However, though 
there were structural concerns, the bass tensions clearly do have a 
tonal goal, and are defined in concert with elevated but safe BP% 
curves. Bass inharmonicity ends up somewhat reduced, but treble 
inharmonicity ends up being increased a  bit as well. In this case, that 
means the treble ends up being pretty close to the original scale values 
(which were high).

Thinking about your comment, and going back over the spreadsheet, I 
could have  achieved the above simplified bass and tenor tonal goals at 
440 (the back and forth on this list always teaches me something). I 
would have had to reduce plain wire cores a bit more in the treble to 
compensate, and that would have reduced inharmonicity up there a 
bit...probably would have been a good strategy. But the bass strings 
have been designed at the 425, so for this one, I think I'll keep things 
there.

What I'm interested in seeing is, though the lower tensions create 
higher treble inharmonicity values relative to higher tension modern 
scales, what audible effect  this higher inharmonicity has. Will it have 
any audible effect at all, in the the big picture? Power will be 
reduced, but what other effects will or will not be audible?


-- Jim Ialeggio

jim at grandpianosolutions.com (978) 425-9026 Shirley, MA


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