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<DIV>Del:</DIV>
<DIV> </DIV>
<DIV>I just wanted to thank you for your articulate and concise
statement. My understanding has always been that the open front
counterbearing increased the sustain in the speaking length because of the
transfer of energy back and forth across the capo. Am I reading you
correctly?</DIV>
<DIV> </DIV>
<DIV>Paul </DIV>
<DIV> </DIV>
<DIV>
<DIV>In a message dated 3/15/2011 11:50:34 P.M. Central Daylight Time,
del@fandrichpiano.com writes:</DIV>
<BLOCKQUOTE
style="BORDER-LEFT: blue 2px solid; PADDING-LEFT: 5px; MARGIN-LEFT: 5px"><FONT
style="BACKGROUND-COLOR: transparent" color=#000000 size=2 face=Arial>1)
With an inefficient termination--i.e., a V-bar with shallow string termination
angles and "tuned" front duplex string segments on the other side--energy can
be transferred back and forth across the V-bar. Because the duplex string
segments are tuned (in theory, at least) to some calculated partials of the
speaking lengths, vibrating energy at or around the resonant frequencies of
the duplex string segments will pass back and forth across the V-bar with
relative ease. Among other things, this has the effect of increasing the rate
of decay in the desired speaking lengths because some of the energy that is
transferred across the V-bar to the duplex string segments is absorbed into
the plate at the front bearing bar. This loss is in addition to whatever
amount of energy is absorbed into the plate at the V-bar.<BR><BR>Since the
so-called "tuned" duplexes are rarely, if ever, accurately tuned, these
vibrating portions of string can, and often do, produce sounds at undesirable
pitches that are close to, but not quite on, some harmonic of the normally
speaking strings. As well, because the string deflection angles are shallow
and vibrating energy is being transferred back and forth across the V-bar, any
slight imperfections in the shape or surface texture of the V-bar can, and
often do, create undesirable vibrations or "string noises." In an effort to
control both dissonant vibrations and the string noises it is a common
practice to mute the front duplexes. This damping absorbs some of the
vibrating energy in the duplex string segments but it does not stop the
transfer of vibrating energy coming from the desired speaking lengths of the
strings to the duplex string segment. That transfer continues but it's now a
one-way street; energy is being dampened on the duplex side of the V-bar and
is now unavailable for any transfer back into the speaking side of the V-bar
so the decay rate in the speaking string increases even more and the sustain
time further decreases.<BR><BR>2) When the string angles are greater
than about 15˚ to 18˚ and the duplex string segments are kept reasonably short
energy is not freely transferred back and forth across the V-bar between the
speaking string segments and the duplex string segments. The termination of
the speaking strings at the V-bar is more efficient and most of the energy
arriving at the V-bar is blocked and reflected back into the speaking string
segments. Some energy, to be sure, is still absorbed into the V-bar and/or
capo tastro bar but very little makes past the V-bar it into the duplex string
segments. In this case damping the duplex string segments makes little
difference because there is little energy there to be damped. <BR><BR>As an
added benefit, because the strings are not "rocking" back and forth at
the V-bar, its shape is less critical and string noises are virtually unheard
of. <BR><BR>3) The back scale is a whole other issue. Energy is not
being transferred from the speaking strings across the bridge terminations and
to the backscale portion of the strings. The backscale is set in motion by the
motion of the bridge(s). Whether or not the backscale string segments are
tuned does not materially affect the vibrating energy in the speaking portion
of the strings or their decay rates and, hence, will have little, if any,
effect on how they vibrate or how long they vibrate. <BR><BR>Whether tuning
the backscale string segments has any positive effect on overall piano
performance is, for me, at least, an open question. I have yet to see it
conclusively demonstrated by even the most ardent supporters of the scheme.
Keeping an adequate backscale length is clearly important but deliberately
tuning the backscale to some partial lengths of the speaking strings has long
seemed an exercise in futility. Besides, given the broad spectrum of
fundamental waveforms and partials driving the bridge(s) at any given moment
(while the piano is being played) it would be well-nigh impossible to avoid
finding backscale lengths that are not "tuned" to some fundamental or some
partial of some note or other. <BR><BR>ddf<BR><BR>Delwin D Fandrich<BR>Piano
Design & Fabrication<BR>6939 Foothill Court SW, Olympia, Washington 98512
USA<BR>Phone 360.736.7563 — Cell
360.388.6525<BR>del@fandrichpiano.com —
ddfandrich@gmail.com<BR><BR><BR>-----Original Message-----<BR>From:
pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On Behalf Of
David Love<BR>Sent: Tuesday, March 15, 2011 4:10 PM<BR>To:
pianotech@ptg.org<BR>Subject: Re: [pianotech] Tuning the duplex
sections<BR><BR>Yes, that's right of course, went too far with that
idea. <BR><BR>So then why exactly does muting the front duplex kill the
tone? Even a light muting in which the rocking motion is presumably
unimpeded. What does the front duplex contribute in that case (when it's
unmated) and how does it contribute. Similarly, why does muting the
front duplex in a piano with a very short duplex not kill the tone nor does
the tone suffer, seemingly, from having a very short front duplex.
<BR><BR>David
Love<BR>www.davidlovepianos.com<BR></FONT></BLOCKQUOTE></DIV></FONT></BODY></HTML>