Three Bridges with Scaling Puzzle

[PatWilbur@aol.com]

I'll state my general question before I go into the details, since I think it
will generate some interesting discussion.

What effect, in general, does string tension have on sound? I gather from
recent posts that the lower the tension, the higher the inharmonicity. Please
correct me if I am wrong. And from my other reading, average plain wire
tension is 165 lbs.

I am working on a Straube baby grand which measures about 4'4" with the lid
off. There are three bridges and no agraffes. There are 22 single wound
strings, 8 bichord wound and 9 trichord wound, with 19 on the separate bridge.
This leaves 59 trichord plain wire unisons.

Not only did the plain wire scaling also appear rather odd, but to further
complicate matters I made some sort of grievous error in recording it. By the
time I got back to it again I didn't have a clue. A local RPT rebuilder looked
at it and made some suggestions, but he said the bridge was curved oddly -
"dramatically foreshortened" - and even he wasn't sure. From a recent PTG
journal article I got the formula to calculate the tensions, and decided to do
so before I started restringing. Well, after I saw the numbers - some as low
as 94 lbs - I held off on the restringing.

So other than my initial, general question, here are the others:

Would this type of small piano have been designed with lower than normal
tensions in the first place? It appears so, with the longest speaking length
of 32" resulting in only 112 lbs tension even with the #21 wire I found on
there.

Anyone have a clue what "original" was for the piano? Ever seen one of these
critters? Even without my recording error, I can't be certain. It was pretty
well toasted when I got it.

At what point in lbs tension should I be concerned, recalculate, and try
something else? Is there a minimum cutoff? This goes back to the question
about the overall sound. On the other hand, I don't want to overdo it and have
it go bang in the night.

Finally, how good a piano is this really and how much trouble may I want to go
to for it? I haven't yet decided how far to go on some things - so far I'm
assuming this is an inexpensive baby grand.

Looking forward to your comments,

Pat Wilbur, Associate
Fort Worth, TX