[CAUT] pre-stretching new string?

[David Love]

I see my spread sheet date didn't come out too well.  Let's try that again
with all the corrections.   

 

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

-----Original Message-----
From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of David
Love
Sent: Monday, June 11, 2007 6:58 AM
To: 'College and University Technicians'
Subject: Re: [CAUT] pre-stretching new string?

 

 

 

In Robert's book "The Calculating Technician" the formulas are given and you
can program your own spread sheet.  The original claim was that when
comparing the degree to which two strings will go out of tune with a change
in length, the break point percentage was an indicator of which string would
go out of tune more.  The other statements below came about as a discussion
of the math.  If you do as I said and compare two strings which start out
with different BPPs and calculate the change in tension for a given change
in length (say 5 mm) and then see how that translates to a change in
frequency, you will see that the one with lower BPP will have a greater
change.  You have to reprogram your spreadsheet to make that calculation or
just do the calculations separately since the spreadsheet is not generally
set up to have Frequency as a dependent variable.  First determine the
change in tension for a given change in length.  Then calculate the change
in frequency for a given change in tension at the new length.  Then
determine which frequency changed more.  

 

 

Note            Length             Diam            BPP
Tension                  Frequency

 

            A - 7             70                    .032               76%
138.64                    3322.44

            A - 7             60                    .032               56%
256.85                    3322.44

 

David Love
davidlovepianos at comcast.net
www.davidlovepianos.com <http://www.davidlovepianos.com/>  

 

 

 

 

 

 

 

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