Wound Trichords

[Lesher, Trent J.]

Hi Ron,
 
Looks like you did some figuring for me!  Thanks a lot, that illuminates the situation in such a detailed way.  That C# measures about 0.043" with my calipers, by the way.  I got readings between 0.0415 up to 0.044, so the average is about a #19?
 
Now I would like to ask a question I asked several times many months ago on this list, and never got any response to, except one which kind of ridiculed the idea without explaining why exactly.  
 
Do you think there is ANY merit or possibilities in the idea of using softer steel or iron wires, such as the ones offered for the restoration of pianos that originally did not use modern steel music wire, in those lowest plain wire strings in my piano or others with similar issues.  Such wire is, I believe, more flexible, and the % of breaking strain would be raised, which I think I would reduce the sharpness of the partials to make a better transition.  I guess it would not improve tuning stability, since the absolute tension would be about the same.
 
I looked up the one response I had previously gotten on this question, and it was "The modern steel strings were so designed in order to increase the power output of the piano. Start putting in low tensile iron strings in a piano and there will be a remarkable down-turn in power...Has anyone tried using thorn needles on their CDs yet?"
 
And the question I had and still have about that was, Do you get the advantages of all that power when the modern string is at relatively low tension compared to its elastic limit -- maybe close to only half the stress on the material compared to the most stressed string on the piano?  And would you lose any power by using a softer string *at the same absolute tension*?

As I understand it, some of these alternative strings have a composition similar to modern wire but are annealed or cooked differently.  

I am thinking that the increased gross tension that the iron plate made possible had a lot to do with the increased power.  But in parts of a scale that don't have the the benefit of the longer strings or a particularly high gross (absolute)tension, what's the big benefit to modern wire?  The alternative string would still be the same length, could be the same guage and tension, too.  Does the softeness = more internal friction losses = shorter sustain time?

I guess the increased stiffness of the modern wire makes it brighter, and raises the Q factor, too (longer sustain?).  Still, the stiffness means higher inharmonicity, which is undesirable just above the break of small pianos, isn't it?

Just wondering if there would be any point in entertaining a scheme of, say, using wound bichords for C# and D, then a wire that's annealed or whatever to be slightly softer for the next few notes.  

I would be really interested in your opinion about that.  I know there are some manufacturers of this alternative type of wire who recommend exactly the sort of thing I'm talking about, but I'd like to hear from you or someone else who does rescaling and rebuilding of modern instruments and what your thoughts are and if you've discarded the idea, why.

Thanks again, Ron, for the detailed break-down you gave of the situation with this particular upright and other pianos with similar scale issues.

Best regards,

Trent Lesher


	-----Original Message----- 
	From: Ron Nossaman [mailto:rnossaman@cox.net] 
	Sent: Sat 11/20/2004 12:17 PM 
	To: Pianotech 
	Cc: 
	Subject: Re: Wound Trichords
	
	


	>I had actually been thinking one way to improve the tone of the last
	>couple notes at the low end of the long bridge on my M&H 50 -- C#3, the
	>lowest before the break, is 38-3/4" long -- would be to replace the plain
	>wires with wound ones.  Now it seems mayybe I am full of misconceptions
	>and this is a bad idea -- but why?
	>
	>Trent Lesher
	
	
	Not a bad idea so much as a less than ideal fix. Putting the wrapped
	bichords on the low end of the tenor bridge will likely make it less bad,
	if it can be made to fit into the scale. For instance, that 38.75" C#-3
	with plain wire trichord will be at about 24% of breaking tension
	(regardless of wire size, within reason). That's pretty low, and will be
	very reactive to tension changes resulting from humidity fluctuations,
	meaning it will go out of tune quicker and farther than unisons farther
	up-scale, or down scale in the high bass. Tension will be determined by the
	wire size used there. For instance, unison tension with #20 will be about
	404 lbs, or about 369 lbs with #19. Going to a bichord unison, dropping two
	or three half sizes for the core, and figuring wrap to get back near the
	unison tension that was originally there will raise the break% to around
	40%. That's going to be a more stabile unison with humidity changes, and
	sound better too. The trouble is, that puts you at the bottom of the list
	of available copper wrap sizes, requiring about a 0.007" wrap to keep the
	tension down around where it was with the plain strings. Arledge uses as
	small as 0.006" for copper wrap. That takes care of C#-3, if the impedance
	and inharmonicity connects reasonably with the high bass. Now you'll
	probably want to go 2-4 notes higher with wrapped bichords to blend the
	impedance and inharmonicity into the rest of the treble. What happens? You
	maybe need 0.006" wrap for D-3, and smaller than is available for the next
	one or three. There's the problem, and the reason this doesn't always work
	that well, and the reason for transition bridges. The speaking lengths are
	too long at that pitch for wrapped strings. What you can get away with
	depends on the individual scale and what you have to work with.
	
	Ron N
	
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