Official Luthiers Forum!

I've looked at the d-addario spreadsheets and I'm not seeing how it works.

I've found a few online ones that are supposed to help you find the guage of strings you want to get a certain tension.

I'm trying to find out what tension at what scale length the set of strings I want to use will be.

The mission is to find out how much more overall tension a 12 string set will have over the regular six string sets I use, so that I can calculate how much stiffer I need to make the soundboard so it won't collapse.

Does anyone know of an online one that provides that function?

It would help a lot...

Just my opinion, but those are are always wrong.
Their estimations always seem a little high.

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"Act your age, not your shoe size" - Prince

Ed,

You can create your own spreadsheet for any scale length and string gauge. The formula for the string tension is given on the D'Addario website here together with the relevant note frequencies and a downloadable pdf of the different string unit masses.

If you are after a target string gauge for a certain tension, note and scale length you find it by inserting different string gauge unit masses in the formula until you get closest to your target.

_________________
Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

Chris,

Probably better high than low for my purposes...

Dave,

I think after sleeping on it, I understand how that chart works. However, if I'm doing the calculation right (which I very well might not be) I get a higher number for a calculated string than is published on the package of the actual string. I suppose that's better than the opposite for my needs., and what Chris was saying.

I think the simplest route would be to tally the tension published on each string set and go with that, and just ignore the fact that the switch from 25.5" they calculate from will diminish slightly when switched to the planned 25" scale.

Or perhaps I could go 25.5 divided by 25.5 to get .98, meaning it would only be 98% of the tension. Thereby at that level of closeness, may as well just use what it says on the string packs and forget the scale length change.

Well, that was easy...

Or failing all of that pm me your e-mail address and I'll send you a spreadsheet I made with all of the string mass and note frequencies in it that you can use - simples.

_________________
Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

Dave, that's would be fantastic!

PM sent...

The tension change is not linear with scale length, since it's involved in the squared term (2*freq*scale). But true, the difference going from 25.5" to 25" is not that much (I get 96%).

I use the D'Addario string tension chart and Windows calculator (in scientific mode for the x^2 button) to figure my string tensions when designing harp guitar type instruments. Using the equation in the chart, I get the same numbers as listed in the chart and on a couple string web sites. So the total here should be accurate: http://www.stringsbymail.com/store/daddario-phosphor-bronze-12-string-acoustic-guitar-ej38-light-1511.html, at about 252lbs. Which is 242lbs at 25" scale. 216lbs if you tune down a half step (divide by 12th root of 2 squared, because the frequency is also in the squared term).

Brilliant!