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<DIV>In a message dated 11/12/2003 8:47:34 PM Pacific Standard Time, davidlo=
vepianos@earthlink.net writes:</DIV>
<BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue =
2px solid">
<DIV><FONT face="MS Sans Serif" size=2>Based on recent experiences which=
have me viewing older soundboards with a degree of suspicion, the question =
I have is whether or not crown necessarily equates to stiffness. If th=
e issue with soundboards is whether or not they have adequate stiffness to c=
reate that opposing spring, is measured crown enough of an indicator? =
In other words, is it possible that a soundboard may show adequate crown but=
not have adequate stiffness to perform properly when loaded? </F=
ONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV>
<DIV><FONT size=2>David Love</FONT></DIV>
<DIV><A title=mailto:davidlovepianos@earthlink.net href="mailto:davidlov=
epianos@earthlink.net"><FONT size=2>davidlovepianos@earthlink.net</FONT></=
A></DIV>
<DIV><FONT size=2></FONT> </DIV></DIV></BLOCKQUOTE></DIV>
<DIV><FONT face="Times New Roman" color=#000040 size=4> &nb=
sp; Dave</FONT></DIV>
<DIV><FONT face="Times New Roman" color=#000040><FONT size=4> &nb=
sp; It depends on how you define adequate. The answer to y=
our last question is yes but more often no. I've seen very fl=
exible boards with good crown that still had sufficient stiffness. An Ivers =
& pond 6 ft. comes to mind. It had short ribs but a . 400 thick panel &a=
mp; high tension scale. An awesome piano with amazing sustain. It seeme=
d to depend on more panel stiffness. When strung the board was flat. And unl=
oaded it sprung up a mile. It's less common to have good looking hemispheric=
al crowned board that exhibits stiffness produce a bad sound, but it happens=
as you know. The sustain was like an organ.</FONT></FONT></DIV>
<DIV><FONT face="Times New Roman" color=#000040><FONT size=4> &nb=
sp; As one works with a variety of sound boards a good deal can be=
determined by a tactile sense about board stiffness. I didn'=
t mention as to how stiff this L board was. It was very stiff. As stiff as a=
ny rib crowned board I'm accustomed to. </FONT></FONT></DIV>
<DIV><FONT face="Times New Roman" color=#000040><FONT size=4> &nb=
sp; What do I mean? This will answer Crashvalves question as well. Whe=
n pre-stressing a board with good legitimate crown values as I described, it=
does require having the plate in and secured with bolts & screws. Enoug=
h so that when driving the maple wedges between the struts and the bridge to=
ps it (the plate) doesn't flex. Typical deflection values will be rough=
ly 3 mm at the central strut 2 mm at the first tenor strut & 1 mm or may=
be only .05mm at the top. The low tenor strut about 1 to 1.5. Glenn, these w=
edges are pushed in with my thumb while I'm pounding on the bridge top with =
my fist until it feels like I'm pounding on a gym floor which means it's ver=
y resistive to further deflection. The exception is the low tenor. It's=
not good practice to get overzealous here this very flexible & thi=
nner corner of the board driven by more mass & so requires less bea=
ring anyway.</FONT></FONT></DIV>
<DIV><FONT face="Times New Roman" color=#000040 size=4> In more =
flexible boards you could drive them into reverse crown if not careful.Thes =
also usually have nominal crown. ie. 3 mm on the longest ribs unstrung. =
;This to me is not crown These are the ones I'd be tonally suspicious o=
f.</FONT></DIV>
<DIV><FONT face="Times New Roman" color=#000040 size=4> Dale</FO=
NT></DIV></BODY></HTML>