Steinway B Scale Conversion

[John Delacour]

At 5:02 pm -0500 2/4/07, Ron Nossaman wrote:

>>Let others calculate the tension of that scale and see who they 
>>think has the more reason.
>
>I certainly wouldn't spec a scale like this, but...
>
>>The lengths for the 20 notes on the bass bridge are printed below. 
>>When I see a bass scale that requires the wire for the greater part 
>>of the scale to operate at over 80% of the actual breaking strain, 
>>as high as 86% for one note, I know I'm looking at a recipe for 
>>disaster.
>
>I show C-1 at 68% and 377lbs as the highest. What are you using to 
>determine these percentages?

In practice a No. 21 core with covers 70 and 170 will end up at 
roughly 5.54 mm depending on who makes the string and how good a day 
he's having.  That gives a tension of roughly 351 lbs.  I have the 
breaking strain of mwg 21 as 405 lbs. so that gives 87%.  Paulello 
has 414 lbs as the breaking strain of his No. 21 'M' (modern) wire, 
so very close to the figure I have always used.  Juan Más Cabré 
<http://www.puresound-wire.com/> gives (245 kg) 540 lbs for No. 21 
"modern wire" and 470 lbs for his own, neither of which figures I 
find in the least credible.

It is clear from this discrepancy and from a recent difference in our 
figures in another thread that you have a list of breaking strains 
considerably higher than mine, which I obtained from the manufacturer 
many years ago and which have served well for the bass string 
manufactory for as long.  I never intentionally make a bass string 
that exceeds 70% of the breaking strain as per my list.  Since I am 
human I occasionally punch in the wrong length or something and 
inadvertently send out a string (or even, most memorably just before 
last Christmas, a whole set) that is over-tensioned.  My pocket and 
my serenity begin to suffer quite soon after as the customer's new 
strings begin to go bang.

I am interested to know where you got your list of breaking strains 
which differs so greatly from mine and Paulello's.  Please send me it 
off list and let me know its origin.  Yours seems to be similar to 
Más Cabré's, which, as I have said, I do not regard as serious.  With 
very few exceptions among the hundreds of calculated bass scales I 
have, piano makers keep within the limits I have stated and models 
that exceed them have problems with breakages, for example the 
Bösendorfer I mentioned earlier.  Schiedmayer & Soehne and Grotrian 
are two makers a few of whose models have grossly exceeded the 
limits.  One string I always recognise when it comes in the post for 
replacement -- I have lost count of the number of these I have 
replaced with scaled down versions --is note 13 on the Blüthner 6'3" 
style 6/7.  The original string is 126.1 cm. long and has a No. 19 
core with an overall diameter of 3.38 mm.  That gives a tension of 
roughly 280 lbs. and requires the core to be at 82% of breaking 
strain.  This string (and the one below) will _always_ break even 
though these Poehlmann wire used was far superior to what we have now.

I should add that a greater margin is required for covered strings 
than for plain wire owing to the eye.  I know it is possible to 
exceed the 70% limit for plain wire strings and the extreme treble of 
many pianos does so, not to speak of several "long scales" I could 
think of, Schiedmayer again being a foul offender.

JD