Mike's Oud Forums

String Calculator !

Danielo - 4-27-2010 at 03:09 AM

Dear oud friends,

I took some time to make a simple string calculator..... It is useful to build a custom set using lute strings.

You simply enter the string length and pitch (i.e. 440Hz or anything else), then the spreadsheet gives the tension for various kind of strings, using all possible arabic tunings.

So far I entered the data for all the Aquila and Savarez strings (wound and plain), and plain nylon (from any manufacturer).

Data about Pyramid strings is still missing (not found on the net yet) but if there is some interest I can try to include it as well :)

I hope you'll find this useful !

Dan

Attachment: OudStringCalculator.xls (141kB)
This file has been downloaded 976 times

corridoio - 4-27-2010 at 03:26 AM

Hi Danielo
this is a very useful link about string tension calculator, it was linked several times here in mikeouds but one more time I think is not so bad.. there are values for gut, nylon, nylgut and also metal strings for everybody involved with instruments that use it and an online calculator but anyway one can use the values in a personal excel document:
http://www.cs.helsinki.fi/u/wikla/mus/NewScalc/

Here also the table of conversion of string tension between nylgut-nylon-pvf directly from aquila strings website:
http://www.aquilacorde.com/en/corde-per-musica-antica/our-products/...

Ale

Danielo - 4-27-2010 at 04:05 AM

Hi Ale,

I am aware of this online calculator thanks (although the java applet does not work on my linux).

The main interest of this spreadsheet is to give also the tension for the wound strings, for which the actual string data from each manufacturer is needed.

Dan

jdowning - 4-27-2010 at 06:14 AM

I posted a set of Pyramid string tension tables (with permission of Pyramid) for download on this forum back in July 2006. You might find this data to be of interest.
Do a search for 'Pyramid String Tension Tables'.

Danielo - 4-27-2010 at 11:46 PM

Thanks John for the Pyramid data !

I can include it in the file but it does not seem to arouse much interest :(


Dan

Aymara - 4-28-2010 at 02:22 AM

Quote: Originally posted by Danielo  
... but it does not seem to arouse much interest :(


130 clicks so far tell us the opposite ;)

I think, it's similar to my homerecording thread ... only a few people respond, but MANY are looking and reading. We'll see, if the downloads of your XLS table will rise.

fernandraynaud - 5-5-2010 at 04:38 PM

I think this is a very important contribution to the whole. The ultimate thing we need is a general program that does not need specific manufacturer string part numbers, but rather works on generalized properties and string gauges. The problem with a spreadsheet is that it's a lot of surface area to look at. I personally like tight user interfaces.

Once we have the general equations checked so that they work well enough for multi-material wound strings (as they do for solid materials), some simple entry for a given string type from a manufacturer should be enough to make it "available" in all gauges. For a given string type it should be enough to enter two known points of note, scale, tension and pitch to have the program inter/extrapolate within reason.

There are no "oud strings". The same types of strings are used for guitar, lute, and other instruments, but at different scale lengths, tunings and tensions. For instance the silverplated copper round wire wound over nylon filament core is very common. The windings traveling over a smooth fingerboard provide much of the oud's typical buzzy bass timbre. And then there are some very specialized strings, that have probably never been tried on the oud, like Thomastik's KR strings that use a silverplated copper flat wire on a loose pleated iron rope core !? (my next try for classical guitar, on which they offer low tension and allegedly astounding sustain).

Without a generalized program it takes more work to figure out which gauges to use on which courses, most people wouldn't even dream of trying.

If I have enough data I can write the program. Once we get to that point, we can start trying a much wider variety of strings that might normally be marketed e.g. for lute or guitar, without relying strictly on trial and error, and especially without fear of stressing the oud.

The timbre of the oud is made up of several elements we can control, and others that are fixed. Without straying into bastardized hybrid instruments, it would be lovely to have more control in bringing out the character of individual instruments. Let's say I have an Egyptian that I want to bring up more sustain on. I can reasonably control the height of the strings (a bit with the loop height, and more with the adjustable neck on Fadi Matta and Sukar ouds), the hardness/smoothness of the fingerboard (with coatings that can be added or removed), and although we don't modify the bowl, soundboard and bracing etc, we could use very different string materials, quite beyond the usual "oud strings" the providers offer us.

Sazi - 5-5-2010 at 07:04 PM

I wish it were that simple that we could just use string calculators.

There are many things which affect the tension, perceived or real, of a string on an instrument.

In an ideal world one would be able to calculate the tension, string diameter etc. simply by using the calculator, but I'm sure I'm not the first to have damaged an oud severely doing just that.

If you look at the tables of Matthias for instance you will notice that the string sets he recommends for 57cm oud are thicker than those recommended for a 60cm oud...
Despite the seemingly obvious theory regarding scaling things down on a smaller instrument, on the surface it makes sense, a shorter scale would need higher tension (therefore thicker given the same materials) yet I have a 58.5cm and a 57cm which use the same guage strings with the perception of the same feel due to the 57cm having a higher break angle over both the bridge and the nut. These things are not taken into account with string calculators and can have an enormous bearing on the outcome.

I think you fixed bridge players have it a bit easier there, not so many variables, though I have found that even then, where say, a Ramazan oud creates higher tension compared to an oud with a flat face with the same guage strings . (The bridge area has a dip, the rear of the oud face is slightly raised, giving a different geometry).

fernandraynaud - 5-5-2010 at 08:39 PM

Sazi, if we shorten a string, keeping the material the same, the pitch goes up. If we wish to keep the pitch the same, we have to loosen the string, less tension, not MORE as you were saying. And of course Matthias uses fatter strings for shorter scale, to keep the pitch and tension the same, you need fatter strings. I suspect the 1.5 cm diff between your 57 and 58.5 cm ouds is not enough to be very noticeable in tension, regardless of break/angle. It's very confusing, but I think in time the math will work out.

Sazi - 5-5-2010 at 09:36 PM

Quote: Originally posted by fernandraynaud  
Sazi, if we shorten a string, keeping the material the same, the pitch goes up.


No arguments there.;)
Quote: Originally posted by fernandraynaud  
If we wish to keep the pitch the same, we have to loosen the string, less tension, not MORE as you were saying.


Where did I say that?
Quote: Originally posted by fernandraynaud  
And of course Matthias uses fatter strings for shorter scale, to keep the pitch and tension the same, you need fatter strings.


No arguments there either;)
Quote: Originally posted by fernandraynaud  
I suspect the 1.5 cm diff between your 57 and 58.5 cm ouds is not enough to be very noticeable in tension, regardless of break/angle. It's very confusing, but I think in time the math will work out.


Well, I thought it should balance out too, the difference in length suggesting the tension would be lower, but the difference in break angle of both the head and nut make more difference than either of us suspected, I forgot to mention also that not only is the break angle over the bridge higher, it is compounded by the fact that the soundboard slopes back lower at the back, not folded, sloped, as in the M. Fadel style when he wasn't using the fold, (the whole soundboard is curved).

Anyway, the upshot of it is that both ouds use the same guages and both FEEL the same tension-wise, whereas using a string calculator gives me thicker strings with their correspondingly higher tension and the result being a damaged oud...

fernandraynaud - 5-5-2010 at 10:33 PM

Sazi, I wasn't playing "who's wrong". It's hard enough keeping this stuff straight, I thought it was backwards when you were saying "a shorter scale would need higher tension".

If I can't TELL which has more tension, it's impossible to say what didn't contribute to it. Maybe the angles play no role at all.

And if I can't tell any difference when I use the same strings on two different ouds with slightly different scale, and a string calculator tells me to use slightly thinner strings on the slightly longer scale, and I don't, I wouldn't think the difference is going to be large enough to damage the oud.

But maybe I'm just not feeling it, yet by NOT listening to the string calculator, I am stressing it?

If by "tension" we understand something like "the impression of resistance to deflection", that also may be an issue, like how we perceive "tension", because maybe THAT could be different with different topologies, where in fact the actual tension, as in "pull on the bridge" is the same.

Probably we should run some tests with a little digital sensor we could place in-line on a string without wrecking the string? Like maybe tie the string to a tiny sensor past the nut and leave the string uncut so we can put it back on the tuning peg, with a pigtail going temporarily from the load cell to the tuning peg? You know anything about load cells etc? I can write the software and make a little circuit.

If we could answer some of our basic doubts and questions this way, and get/confirm some measurements on mixed materials, we could move on to creating a general little program we all trust?



Sazi - 5-6-2010 at 12:28 AM

We went over the whole topic of tension/angle/downforce etc. some time ago, somewhere here in the forum is a whole thread with links to other sites and a lot of info but I'm darned if I can find it!

corridoio - 5-6-2010 at 12:40 AM

from liutaio mottola website about the breakangle in floating bridge:
http://liutaiomottola.com/formulae/downforce.htm

fernandraynaud - 5-6-2010 at 01:08 AM

The down-force on the floating bridge is a whole different issue. When we say a reasonable string tension on a fixed bridge oud is 4 Kg, it's longitudinal tension that threatens to pull off the bridge or spoon the soundboard. The total tension may not be affected by break-angles, but if you have a floating bridge oud the total tension is not what you are concerned about. I see now where you were headed with this.

I don't have a floating bridge oud, nor do I know what an acceptable range of longitudinal tensions is. Of course the break angle influences how much down-pressure there is on the soundboard, how much is longitudinal pull at the anchoring, but there are so many differences, it's almost an entirely different instrument.

So what is considered a reasonable L-tension for such an oud?

Sazi - 5-6-2010 at 02:51 AM

Thanks Corridoio! Isn't that a great site!
Quote: Originally posted by fernandraynaud  
... but there are so many differences, it's almost an entirely different instrument.


Definitely no argument there!;)
Quote: Originally posted by fernandraynaud  

So what is considered a reasonable L-tension for such an oud?


Well I suppose Mathias is the best one to answer that, but as we have seen, the different methods of construction and variables have a bearing on that. It has been my experience that there is no "one size fits all" when it comes to oud strings, apart from the aforementioned variables there is also a matter of personal taste, some like a higher tension, others may prefer lower, and in the end we can never know unless we have tried a set, perhaps using the calculator as a starting point, and taking notice of how the instrument responds and feels, making adjustments from there if necessary.

Danielo - 5-7-2010 at 12:34 AM

Thanks Chris, Fernand and Sazi for your feedback :)

I agree that a program that can compute the tension for any wound strings would be more convenient but, alas, they are so many physical parameter involved in the construction that I doubt one could find a universal formula... And also one should take into account that, for the wound strings, the string manufacturers don't provide lot of different sizes so it is important to know which choice is the closest to the desired tension...

When I'll time I will include the pyramid data from John!



Dan


PS: Fernand did you try the plastic wound strings from Savarez ? I am interested because they have probably less buzz than metal wound for the third course, but I am afraid that the wiring would not last long with the rish strikes..

fernandraynaud - 5-7-2010 at 04:18 AM

Danielo, no I have not. I am very happy with Daniel Maris except two things.

I wanted a brighter buzzier timbre on the top cc and gg plain nylons, more like the silvered copper wound DD third course, and I find I can get that by using a little rosin on the risha. For an Egyptian timbre, the plain nylon sounds ok.

Secondly, my Sukar shipped with a 0.051" bass string, but not a very high quality one. The Daniel Mari (and most other sets) offer no thicker than a 0.041". That sounds a little weak and floppy. So I am looking for a fatter Bamm string, and will probably try a Thomastik guitar string.

Luttgutt - 5-7-2010 at 05:23 AM

Quote: Originally posted by fernandraynaud  
Danielo, no I have not. I am very happy with Daniel Maris except two things.

I wanted a brighter buzzier timbre on the top cc and gg plain nylons, more like the silvered copper wound DD third course, and I find I can get that by using a little rosin on the risha. For an Egyptian timbre, the plain nylon sounds ok.

Secondly, my Sukar shipped with a 0.051" bass string, but not a very high quality one. The Daniel Mari (and most other sets) offer no thicker than a 0.041". That sounds a little weak and floppy. So I am looking for a fatter Bamm string, and will probably try a Thomastik guitar string.


I use Aquila or Pyramid for the thick base!

rojaros - 1-24-2011 at 07:33 AM

Quote: Originally posted by fernandraynaud  
I think this is a very important contribution to the whole. The ultimate thing we need is a general program that does not need specific manufacturer string part numbers, but rather works on generalized properties and string gauges.

Hi Danielo,
Thanks for the great spreadsheet. Unfortunately, for general physical reasons there cannot be any 'general' string calculator for wound strings.

Why?

Because the tension of a given string depends on too many parameters that are not programmable:

- ratio of the diameter of the nylon kernel to that of the winding
- kernel material and making (how many strands, how thick etc.)
- the tightness of the windings
- the specifiv weight of the alloy used for the string.

I aprreciate very much the work of Danielo - it is valuably information and he provided us with a simple input for pitch and scale length, instead of having all the tedious calculations done by hand.

Many thanks Danielo, it was exactly what I was looking for!

best wishes
Robert

rojaros - 1-24-2011 at 07:34 AM

PS is there any general cosensus on what is to be considered as a 'good' tension for arabic ouds?

Danielo - 1-24-2011 at 01:55 PM

I'm glad that it's useful Robert..

I'll try to update it with the Pyramids data, but they have so many gauges !

I'm not sure there's a consensus about tension.. the reasonable range is 3,2 to 3,8 kg but people's preferences may vary..

It depends I think of many parameters:
-responsiveness of the oud
-whether the oud is prone to buzzing or not
-light or heavy risha strikes
-near-pickgard vs. near-rosette plucking
-for old ouds, how much the instrument can handle
- the sound one wants to achieve, of course
... and so on.

Personally I prefer low tension (about 3,2 kg), in part because my oud is an ancient one but not only. I also like the warmer tone one gets.

When I lent it to JT for a try he told me "your tension is so low man !" and didn't like it so much.. (but the sound he got from it was lightyears above what I will ever achieve)


Dan




rojaros - 1-24-2011 at 03:27 PM

Thanks, Dan.

So I could start out with something around 3.5 kg (modern Oud but quite responsive) and se in which direction I'd modify.

At the moment I have Daniel Mari strings on it, and they seem to be a bit on the too light side.

Anyway, thanks also for your useful work


best wishes
Robert