more bass scaling questions

[John Delacour]

At 18:12 -0700 21/7/08, Gene Nelson wrote:

>...Note #10 is a monochord with tension of (295lb)
>Note #11 is a bichord with unison tension of 156X2 = (312 lbs.)
...

>Similar situation with noteÊ#30 bichord - unison tension = 232X2 = (464lbs)
>and noteÊ#31 plain steel trichord - unison tension = 149X3Ê= 
>(447lbs) difference is also 17 lbs.
>Again, isÊlooking at the tension of each individual string more 
>significant than looking at unison tension when it comes to tonal 
>color and power?
>Will three plain strings of 149 lbs give similar sound as two wound 
>of 232 lbs?...

Just a few comments on the specific case.  You don't mention how long 
the piano is or other details such as the shape of the long bridge at 
the tenor end, the core diameters, and whether note 30 is on the bass 
bridge or the long bridge,  but even without knowing these things I 
can say that it is a not a nice bass scale.  Unless it is a piano of 
over 7 ft. then 10 notes of singles is not enough and 12-14 notes 
would probably be better.  This would have allowed more flexible 
stings at a higher tension on the lowest pair.  If you play note 11 
and then note 17 you will almost certainly detect a big difference in 
tone quality.  The unnecessarily high tension on note 10 is a fudge 
to minimize the 10/11 break.  If the break were higher then the 
lowest pair could be at say 190 lbs on a No. 19 core and the top 
single at 260 lbs on a 20.5 core.  A significant change in tension is 
indeed necessary at the breaks, but the breaks must be in the right 
place to start with.

As to the pair at note 30, I can say without knowing anything else 
that the tension is far to high, probably dangerously so, and 
certainly the jump in tension is excessive, militating against a 
smooth tonal transition.  The tension on the note 31 triplet is 
slightly low but probably the best that could be managed given the 
scale.  It is probably not so low as to give serious stability 
problems as discussed in another current thread. You would probably 
find that making the top pair, note 30, on a 16.5 core to come to 
pitch at about 180 lbs would improve the break.

All this I say as a bass string maker, but without knowing the 
details of the piano in question, so read it for what it is worth.

JD