V Pro discussion

[Doug Richards]

Bob,
I don't have the resource book to look it up, but I'd guess Cast Iron
internal damping is on the order of 0.5% or less.  For the sake of argument,
lets assume the Vacuum processing changes the internal damping by 50%
(extremely unlikely), which makes it 0.75%  Now you attach this to a wood
rim and sub-frame with internal damping of 5% (again assumed).
With this difference in damping coefficients, I just don't see how the
vacuum part noticeably would affect the acoustics.
There are so many other factors that are more dominate acoustics.

I've been wrong before... 
:-)
doug richards
San Jose, CA

-----Original Message-----
From: Robert A. Anderson [mailto:fndango@azstarnet.com]
Sent: Saturday, August 14, 1999 9:37 AM
To: pianotech@ptg.org
Subject: Re: V Pro discussion


This discussion reminded me of something I read quite a while ago. I
quote from Edward McMorrow's THE EDUCATED PIANO (ISBN 0-929738-00-4),
pp. 7,8:

"The plates with the best acoustic properties are those in which a soft
grey iron has been formed during the casting process. This soft iron
damps metallic ringing sounds and hammer noise more than any other type
of ferrous material. This damping ability is maximized when the casting
cools slowly. Slow cooling also produces a soft metal, which
significantly reduces breakage of the strings at the plate termination
point....The most modern casting method is the automated vacuum-pattern
process, which turns out very precise plates with awesome rapidity. This
method has facilitated the development of a mass-production,
assembly-line style of piano construction. All plates are precisely
alike, and as little sand as possible is used to produce them. These
plates do not damp metallic noise as well as the traditionally-made
plates, and their harder metal causes premature string breakage. It
seems a waste of resources and energy to produce pianos with these kinds
of tone quality and serviceability problems. These casting methods are
superb for producing economical internal combustion engine blocks, but
for quality piano plates they are unacceptable."

Comments, anyone?

Bob Anderson
Tucson, AZ