D'Addario string tension PDF data corrupt

[jack_cat]

The PDF which D'addario offers here:
http://www.daddario.com/Resources/JDCDAD/images/tension_chart.pdf

has a number of errors in what would otherwise be the most useful section to me personally (since I play extended range classicals), on page 10 under the heading "Silverplated Copper Wound on Nylon".

This would be to me the most valuable section, because the serial numbers of these 24 strings include the diameter in thousandths of an inch - a very useful bit of data which is not available elsewhere (if it is please tell me.)

Unfortunately, among the 24 unit weight values (in lbs per linear inch, values which begin with a decimal point and 3 or 4 zeros followed by the 4 useful digits) given for wound nylon strings ranging from .019" to .056", there are 3 values which are obviously wrong: .019 and .020 have the same value, .024 and .025 are out of sequence, and also out of sequence are .054 and .056. On graphing the relationships of UW to diameter in sequence (rate of increase per thousandth of diameter increase), anomalies also appear for .031 and for .040 and/or .041. This means a minimum of 5 errors and possibly 9 out of 24 data points, a 20% to 37% error rate, not very good, you must admit.

In order to check or correct this data it will be necessary to find the packages for a number of different sets of those D'addario string sets with serial numbers which do not contain the diameters, and check the diameters against the unit weights. This would be, or will be, if I get into it, quite a royal pain.

I only noticed this because I got such poor results from using the data taken at face value when I was planning my 9 string fanned classical. If I am able to clean up the data and get a clean data set I will post it for all, but I am not optimistic, it's one of those all night with the calculator things.

As I am planning a new nine string fanned fret classical, I need to do some string calculations. Of course I will probably just end up buying a ##load of different sizes and figuring it out empirically with the guitar in hand...

While I'm on the subject, I'll mention Arto's String Calculator (google that) which works find for the trebles, but I have no way at present to calculate the diameters of bass (wound) strings without D'Addario's formula for finding the unit weight and then using the above-mentioned section of their PDF to convert unit weight to diameter. PERHAPS I will be able to work out an equation for this conversion instead of using their lookup chart - I'm not optimistic. Anybody got some other useful formulas for wound nylon strings?

Thanks everybody,
jack

 

[Winspear]

Yep there are numerous mistakes I noticed in this when checking out classical strings. I had to improvise a bit with the calculator...
I don't think it's a serious as you make out though. Don't take my word for it, but I think some of the larger weight jumps between gauges are normal, for example when another wind is added or something like that i.e. the construction changes.
But yeah, there are numerous obvious errors in that PDF which is very annoying...
Let me know what tuning/scale lengths/gauge idea you come up with an I'll compare what I'd have run.

 

[jack_cat]

Hello Ethereal,
Looks like you and I are the only ones using the d'Addario pdf. I think I am going to try to massage the numbers and formulas and see if there's any way that I can boil it down to spit out an answer in mm of diameter for wound strings in general - then I could make a table and post it for the world... And it's a real pity we don't have a similar document from some other string company to compare it with directly. More to the point, there is at minimum about a 20% error rate in this short section, and that doesn't speak well for the document as a whole. At some point in its creation, somebody had to type in all those eight decimal unit weight values, and I can well imagine them going half blind in the process, and saying, "O it, nobody will ever know if this data is right or not!" And, fact, it's been posted for years and nobody has noticed until now.

I really am not at all sure that I agree with you about the discontinuous jumps due to change of winding materials. It could be, but it could also be that there should be a strict correlation between unit weight and diameter.
I should graph this with the values which are not in question. After all, the metal has to make up most of the actual weight, with a nylon core the weight of the core should be negligible, but this is just my thinking process and the proof remains to be seen.

On other fronts, I think I am back to 600mm / 23-5/8" for my high A4 string, after a thorough reading of all 10 pages of the A4 thread and reviewing my notes. I think you have changed your tune on high and low string lengths since two years ago? Anyway, I have a new full scale drawing hanging up in my studio for contemplation (mostly to remind me to get off my butt and go make the money to build it.) 600 - 720 mm is a nice pythagorian ratio (5/6). Equals 23-5/8" to 28-5/16", the same fan as the prototype of two years ago, (which I have been very happily playing on now that I converted it to an 8 string and solved the problem of having set the strings too close) although the whole thing is 4 centimeters longer (1-9/16").

jack

 

[sevenstringj]

They now have an interactive tension calculator: String Tension Pro

Though I never had an issue using their pdf to put together a balanced 8-string set.

 

[jack_cat]

I had a reply from the D'Addario folks who thanked me for "pointing that out" and sent me a link to the StringTensionPro site as linked in the post above.
- jack