[pianotech] High tension, low tension?

[Albert Picknell]

Del, am I missing something?  You said: "Very simplistically, a high-tensioned scale can be achieved by using a relatively long, thin wire or a somewhat shorter, thicker wire."  And then in the next paragraph you said: "Conversely a low-tensioned scale can be achieved by using a relatively long, thin wire or a somewhat shorter, thicker wire."  Did you actually mean to say that one can achieve both high- and low-tensioned scales by the same means?  Copy & paste error?
 
Bert

--- On Tue, 2/28/12, Delwin D Fandrich <del at fandrichpiano.com> wrote:




No, I’m not referring to the percentage of breaking strength. I’m referring to the absolute tension on each given string. Except in the treble and when selecting core diameters for wrapped strings I don’t pay all that much attention to the “% of Breaking Strength.” In the treble if the % of BS gets too high things break. But this is going to be more a function of speaking length than of wire diameters. Down in the tenor section you’re going to be a long way from the breaking strength no matter what you do. You have a lot more control over this in core of the wrapped strings but even there things are more constrained by work-hardening the core than by voice. I tend to keep core wires on the thin side but still don’t want to stretch the cores above 60% or so.
 
But, back to the question: Very simplistically, a high-tensioned scale can be achieved by using a relatively long, thin wire or a somewhat shorter, thicker wire. Given the right lengths and diameters both can have exactly the same tension. True, the one will have a tension that is closer to the breaking point of the wire but the real issue—to my thinking, at least—is that the short, thick wire will be physically stiffer than the long, thin wire. Assuming they both have the same backscale configuration, hammer strike point and hammer characteristics, both will load the soundboard assembly with approximately the same amount of string downforce but the scale using the thicker wire will have more vibrating energy in the shorter partials and less in the fundamental and longer partials. It will also tend to impede the motion of the bridge/soundboard assembly a bit more, particularly at lower frequencies.
 
Conversely a low-tensioned scale can be achieved by using a relatively long, thin wire or a somewhat shorter, thicker wire. In both cases, of course, these strings will be comparatively shorter than their high-tensioned counterparts. And the same general rules apply; for a given hammer blow the short, thick wires will end up with more energy in the higher partials and less in the fundamental speaking length and lower partials.
 
At least this is what my ears are telling me. More in-depth measurements await.
 
ddf
 

Delwin D Fandrich
Piano Design & Fabrication
6939 Foothill Court SW, Olympia, Washington 98512 USA
Phone  360.515.0119 — Cell  360.388.6525
del at fandrichpiano.com — ddfandrich at gmail.com
 


From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of Roger at Integra.net
Sent: Monday, February 27, 2012 4:29 PM
To: pianotech at ptg.org
Subject: Re: [pianotech] High tension, low tension?
 



Del,

I’ve asked this question of other scale designers and seem to get the same vague answer. The question “high, medium and low” would seem to refer to the percent of tension to breaking point of the wire .Certainly a given wire with a tension at 150 lb. would not address the “high, medium or low” tension question unless one knows the diameter and length of the wire. As you implied, the tonal characteristics change with the tension. Could I assume you are referring to the percent of breaking point, or are you referring to the total tonnage on the piano? Can you clarify?

Roger



 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://www.moypiano.com/ptg/pianotech.php/attachments/20120228/82145da9/attachment.htm>