High-tension or Low-tension?

[John Delacour]

At 10:03 20/09/01 -0700, Delwin D Fandrich wrote:


>The overall tension of a piano scale by itself does little to define it's
>tonal characteristics. This is the sum of individual string tensions and
>those can be wonderfully smooth and consistent or they can be scattered all
>over a rather large ballpark. The typical piano scale--at least those based
>on the scaling technology of the late 1800s and early 1900s will typically
>be scattered all over that ball park. They will be up and down and back an
>forth throughout the bass, often defying any kind of logic; they will
>usually be quite low through the low tenor climbing up rapidly to become
>high to obscenely high through the tenor; they will drop down again to some
>lower figure through the upper-tenor/low-treble; finally, they will end up
>quite low through the upper-treble.

I gave an answer to this question in my message "Re: Standard Pitch 1870 to 
Present" of 18th September, which I think painted an accurate picture of 
the (mainly European) pianos I have examined during my career.  In the main 
these have been pianos of good reputation (eg. most of the big name grands) 
or pianos which had special tonal qualities that I wanted to 
investigate.  The oldest of these were Broadwood and Kirkman straight 
strung grands, the Broadwood out of curiosity and the Kirkman because it 
was an astoundingly good-sounding piano.  I will pass over the name 
Broadwood without any comment since I reckon that the good sound they 
achieved in a few of their models came about by pure coincidence. Brinsmead 
is worth a lot of examination and applied a great deal of attention to his 
string scales as well as to every other aspect of his pianos, which are 
among the very best.

The 6'9" Kirkman of 1860 has as near as possible equal tension (ca. 155 
lbs) from A85 down to the end of the long bridge.  Most of the other pianos 
I've looked at have been German and here I detect two "long bridge 
schools", those (eg. Bechstein, Steinway) who have the bridge follow a 
parabola (as though to achieve equal tension) and those (eg. Blüthner) who 
by putting a bulge in the bridge before the tenor to give your "high to 
obscenely high" tensions in this region.

In spite of our previous discussion of the 50 millimetre C88,  I have not 
found the tailing off in tension in the extreme treble to be all that 
common, tensions found in the mid treble more often being extended right to 
the top.  In this respect I consider Steinway's lighter top to be the 
exception rather than the rule.  It's important, of course, only to examine 
well made pianos, since careless bridge-making and positioning are frequent 
in bad makers.

As to the tailing off of tension at the other end of the long bridge, this, 
to some degree, is almost universal on both grands and uprights and is 
dealt with in different ways as regards the wire gauges used -- Lipp 
achieved an indetectable break in their upright (29 bass notes) by actually 
lowering the wire gauge from 19.5 to 19 towards the end of the bridge.

I admit I have never found a scale that I'd want to imitate in a new piano 
and I wouldn't expect to, but I have found some pretty good scales in the 
"equal tension" class.  I don't bother too much nowadays measuring existing 
scales and one look at the long bridge is usually enough to get a rough 
idea of the quality of the scale.

Of bass scales you say "They will be up and down and back and forth 
throughout the bass, often defying any kind of logic".  I'd say that's not 
the rule, even though much bass string design in the past was left to the 
string-maker, who in England would be given a weight to work to -- if a 
maker's set weighed seven pounds and the price of copper went up, the 
astute owner would tell the string-maker to knock half a pound off the 
weight of his sets so that he could maintain his margin!  The string-maker 
at the same time would be working blind, ignorant of any scientific basis 
for his craft and working to purely empirical traditional guidelines.  One 
of these would be that string-makers don't like working with copper thinner 
than .25 millimetres because you have to be awake, so he will persuade the 
maker to put a few more strings on the long bridge...and so on.  A slight 
exaggeration of the English scene perhaps, but I doubt it.  On the other 
hand a surprising number of bass scales preserve roughly even tension 
through the bichords with a tension curve in the singles depending on the 
length of the piano -- and I imagine the bass of your own pianos follows 
this pattern.    Any "back and forth" is just plain lack of quality control 
-- it could never be intended in the design.

>I prefer to categorize stringing scales--assuming they are of reasonably
>uniform tension--by looking at their average tensions through the
>tenor/treble sections. By my personal definition a low tension scale is one
>having individual string tensions between approximately 150 & 160 lbs (68 &
>73 kgf.). A high tension scale is one having individual string tensions
>above 180 to 190 lbs (82 & 86 kgf). String tensions higher than these don't
>belong on pianos of any type or size.

That categorization matches my own experience and opinion pretty well 
exactly.  I must say when I read people talking of "the massive total 
strain of 23 tons!" etc. I think "so what?" and begin to wonder where it 
all went.  Any scale of mine is likely to end up with a total of about 18 tons.

I found one web site that mentioned your Walter 190 and gave some 
details.  I'd be interested to see one or two of your scales and hear the 
rationale or the mathematics behind them.

JD