Bass string scaling question

[David Love]

JD:

I appreciate your input.  Not to overstay my welcome on this topic but I do
have one key question in all this.  The goal in scaling (for me) is to
create overall balance and smooth transitions between sections.  Different
scalers use different criteria to achieve that, it would seem, and I have
tried a few different approaches.  One can concentrate on tension,
inharmonicity or what Robert's calls the "Z" factor or loudness, or some
combination with varying emphases.  On most existing scales you are forced
to compromise something as a smooth curve on all three is difficult, if not
impossible to achieve.  Of course, it may not even be desirable.   And there
is yet another issue which doesn't seem to be included in these calculations
which is to account for the balance between fundamental and upper partials
as you transition from trichord to bichord to monochord.  Where would your
emphasis be for creating seamless transitions and balance.  Anyone else
please feel free to offer your thoughts if you care to.    

David Love
davidlovepianos at comcast.net 
www.davidlovepianos.com

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of John Delacour
Sent: Monday, May 28, 2007 9:38 AM
To: Pianotech List
Subject: RE: Bass string scaling question

At 7:08 am -0700 28/5/07, David Love wrote:

>I'm not sure I understand the problem with the 33/66 ratio.  Why does that
>create an interference?

By interference I mean that the lengthwise line drawn through the 
tops of the copper coils is wavy and not straight, giving the string 
a very queer look.  It would be interesting to be able to describe 
exactly what happens, but since I know it does happen I simply avoid 
the ratio.  Here's a guess : the frequency with which the peak of the 
top-cover coincides with the troughs in the under-cover causes a 
crushing or squeezing sideways of the inside coils so that the top 
coil forces itself closer to the core.  You might well say that they 
coincide fairly frequently with a 40/60 ratio, but the fact is that 
with this ratio the line of the string is acceptably smooth.

>Also, during the wrapping process, is there some elongation and therefore
>slight thinning of the copper wrapping such that you should build into your
>target outer diameter calculations some factor for that shrinkage, as it
>were.

Absolutely.  Say 10%.  It will vary according to the stringmaker and 
to a small degree, according to the copper gauge.  I made tables 
years ago for my odd string work and for sets I have a factor built 
in to the programme to allow for the stretch.  Thus I specify a 
"target tension" and the programme gives me the actual theoretical 
tension after factoring in the actual copper sizes available and the 
reduction in diameter due to stretch.

If I go on like this, I'll have the boys from the cabal round :-)

JD