Backscale design... Del, anyone?

[Ron Nossaman]

>In a post back on 4/23, Del wrote:
>
>"Especially in short pianos the back
>scale length is nearly as important as the speaking length.  Sometimes more
so."
>
>
>I've been wondering if anyone, Del, Ron, or anyone who has a knowledge of
scale design would like to pick up on this.   Is this referring to the
length of string between the rear bridge pin and the hitch pin that often
speaks in the treble end of the piano?  I've rebuild an old Mason & Hamlin
with the 'half round' aliquots in the rear duplex scale, and tuned each one
to perfection... very sweet sound.  Is that what you were referring to, Del?

* Well, Del has a lot more information on this than I do, but I can give you
the view from the cheap seats. He was talking about making the backscale
long enough to let the soundboard move when the piano is played. The further
down in the scale you get, the greater the amplitude of soundboard movement,
and the more critical backscale length gets. The tuned rear duplex is only
very roughly "tuned" and the impossibility of controlling the string
tensions in these string sections (because of friction across the bridge)
when tuning the piano, means that they are never really tuned. They also
limit the length of the backscale so, to some degree, limit soundboard movement.



>Is it also important to have the sections of strings that we often mute
(the part of the string between the rear bridge pin and the hitch pin of the
wound bass strings for example) in some type of proportional relationship to
the length of the speaking length of the string?  

* I don't think so. Just so they're long enough to not restrict soundboard
movement unnecessarily. Vertical hitch pins help too.


>(I sure hope that came out right.  I've never asked this question before!) 
* If you ask the same question often enough to get it perfected...


> Would that be a possible reason to actually shorten the speaking length of
an already short bass string?

* Definitely! Look at the bridges and backscale configurations of the pianos
you tune and see how short some bass backscales are. If the Mason & Hamlin
you spoke of is an "A", that's a good example. The first few bass strings
are terribly short back there. The designer tried to get a long scale into a
short case and robbed the bass backscale to do it. I just delivered one of
these that has a lot better sounding bass now than the one it came in with.
I eliminated the bridge cantilever and moved the low end of the bridge down
as far as the plate would allow. I'd have liked to have gotten it another
10mm further down, but I was too chicken to grind away the plate there. If
it had been my piano, I'd have done it. In any case, you can make a new
string scale to accommodate the shorter speaking lengths and produce a
better scale than the piano originally had. Longer speaking lengths aren't
necessarily better, and shorter isn't necessarily worse.



>I'm reaching here... having trouble with the words...
>
>Any thoughts?  Are ya up for another 'lesson' Del?  Inquiring minds just
couldn't help but ask! :-)
>
>Thanks,
>
>Brian Trout
>Quarryville, Pa.


Your questions are fine. Do my ramblings make any sense?
 Ron