String tension calculation

Good evening luthiers and clever Ukulele people,

I own a custom requinto guitar/guitalele that I am trying to find the perfect strings for. It has a scale length of 49cm and is supposed to be tuned to A.

First I have tried requinto strings by d'addario, but these were too low in tension. Much lower compared to the tension of the standard strings on the yamaha gl1.

Now I have tried the Aquila Guitalele strings (made for 42cm scale length) and the tension is very high if I tune to A. It sounds and plays wonderfully, yet I am afraid the tension might be too high. It feels even a bit stronger then savarez high tension strings on my 65cm scale length normal classical guitar.

I have tuned it down to G now, it still sounds nice (but not AS nice) but there is some snaring sound in the second lowest string (not because of too little tension, but for some other reason I have no idea about).

Now my questions:

What strings would you recommend for this instrument with this uncommon scale length, if I want to tune to A (or G) ?

How do I know if the tension is too strong for the guitar? (I know, when the bridge comes off -_- )

How do I calculate what strings I need for this guitar?

Thanks and best regards,

Tejaquila


(I hope this belongs into this subforum, if not please move.)

There are several string tension calculators out there. Here's one. http://www.cs.helsinki.fi/u/wikla/mus/Calcs/wwwscalc.html#P1

If it's a custom instrument, I'd ask the builder what they recommend for strings and for maximum safe tension. I don't know enough about those instruments to hazard a guess but standard tension for a full-sized classical typically adds up to 80 lbs (36 kilos) or so.

I've made a few Guitalele type instruments. Actually they really should be called chitarra per bambini after their historical name.
Firstly you have to decide what tension you want to play at. That partly depends on your own preference and the limits of your 'bambini'. A modern Nylon strung classical Guitar is strung at around 7 Kg's per string, for a total of around 40 Kg for a whole set. You can go a lot lower should you wish. I strung mine at around 5 Kg per string, tuned to G. I could have tuned it to A if I changed the gauge of string.
The best way to choose strings is to play around with a string calculator. That way you should start to understand the relationship between Pitch, string length, string gauge and string tension. It might seem confusing at first but stay with it.

Firstly you have to decide whether you want to play at concert pitch - 440 Hz. 440 Hz is the 'standard'.
Select the type of string: eg. Nylon or Nylgut
Your string length is fixed: 420 mm's.
Select the note and the octave that it falls in. So high A will be in the octave c' b'. The correct octave is very important otherwise you will get some very strange results!!
Now select the tension for that particular string. eg. 5 Kg's.
The calculator will then tell you the correct gauge of string that you should buy. Virtually all types of string are available as singles - Nylon, Nylgut certainly are.
Only you (and the maker of your bambini) can decide on the tension of each string. There really is no 'right' gauge or tension but there is a gauge or tension that is too high for the instrument. You might just have to experiment.
Even if you don't want to buy individual strings the calculator will be helpful in choosing a set of strings.

Kent and Michael,

Thank you very much for your informative replies.
I will really have to get into calculating the string gauges as it seems, thank you, Michael, for explaining how to do this - very helpful.
I have also found a set of strings made for 46-50cm string length requinto guitars (by Pyramid strings) - I ordered it to see how it works.
(If it does, maybe I can find the nylgut equivalents more easily..)

But eventually I really want to play on Nylgut again as I absolutely like the “historic timbre“ they have. (For a lack of better words).

Thanks again and good evening,

Tejaquila

P.S.: Michael, I have just checked out your website, fabulously looking instruments. Your simplified baroque vihuela is absolutely beautiful, wish I could have one right now!

D'Addario has a string tension calculator chart in PDF format for all of their strings. I found it on their website, though I don't recall the link. I've found it very helpful for working out the tension on new instruments, scale lengths etc.

There is some fancy math involved, but the equations are given in the chart, so it's not all that difficult to work out what you would be looking at in the way of tension and pitch for their stings given the scale length you are working with. Could help finding strings of similar design in other brands if you don't want to go with D'Addario.

Graham McDonald - another great Australian luthier, and a recent new member here, has a great little string tension calcuator on his web site....
http://www.mcdonaldstrings.com/stringxxiii.html

Hey guys thanks a lot.

I tried to get into calculating the string tension, which seems „do-able“. The thing that really turns out to be my problem is that I have no idea how many kilos total the instrument will take. Or rather, with how many kilos it sounds the best. Sadly, the luthier doesn't really say a number - I might have to bother him again and again.

The second, smaller problem is that I have yet to find a string tension calculator that lets you choose nylgut. There are some with gut and some with nylon, but I would guess nylgut has its own properties?

Thanks and best regards!

Tejaquila said:

Hey guys thanks a lot.

I tried to get into calculating the string tension, which seems „do-able“. The thing that really turns out to be my problem is that I have no idea how many kilos total the instrument will take. Or rather, with how many kilos it sounds the best. Sadly, the luthier doesn't really say a number - I might have to bother him again and again.

The second, smaller problem is that I have yet to find a string tension calculator that lets you choose nylgut. There are some with gut and some with nylon, but I would guess nylgut has its own properties?

Thanks and best regards!

Click to expand...

It doesn't matter. Nylgut uses 'gut equivalent' calculations. So for practical purposes use 'gut' for 'nylgut' tension calculations. That's how Aquila sell their nylgut, it's as though they've already done the conversion for you - in this case they've converted it to pure gut (or real gut).

Someone just posted this string tension calculator on MIMF.
http://stringtensionpro.com
Looks quite complete

A 49cm scale length instrument tuned to A is the same as a 65cm scale length classical guitar with a capo at the 5th fret. (give or take a few mm)
You should probably just use Nylgut classical guitar strings. When tuned up to A and it should feel about the same as a classical guitar for string tension. I would guess that your requinto was made for that type of tension.