[CAUT] pre-stretching new string?

[David Love]

I think it's not so much the bass bridges as it is the tension and break
point percentages of the various sections.  The degree to which a string
goes out of tune will be a function of the break point percentage (BPP) when
it is at pitch (thanks Ron N. for clarifying that).  The lower the BPP, the
greater the change in pitch for a given change in length.  The top end of
the bass section is generally considerably higher BPP than the low tenor,
and the low tenor is usually the lowest BPP in the entire piano and thus
goes out of tune the most with seasonal changes. 

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 Bob
Hohf
Sent: Saturday, June 09, 2007 2:34 PM
To: 'College and University Technicians'
Subject: Re: [CAUT] pre-stretching new string?


I've been following this discussion with some interest, and don't have any
strong opinions or data on one side or the other of the soundboard/bridge
debate.  However, I'd be interested in how the various factions explain the
difference in humidity-related pitch change between the treble and bass
bridges.  We've all observed the same sort of difference with both
solid-body and cantilevered bridges, so I don't think it can be explained by
simply saying, "Bass bridges have more wood, so they expand and contract
more."  And how about those Yamaha C3s where the lowest octave of the tenor
bridge has far greater seasonal pitch swings than any other part of the
scale, treble or bass?  

Just wondering

Bob Hohf