String tension chart

[TonyD]

Hi Guys,

I very much would like to calculate the string tension on my old german double bass. However, I have some difficulties in understand the formula in this thread. Hope somebody can give me a hand.

- Scale length on my bass is 107.cm (42.3 inch);
- I have Pirastro Obligato solo strings (tuned down);

If more info is required I am happy to provide this.

The Pirastro company is not willing to give any tension info whatsoever. So hopefully somebody can help me.

Thanks in advance and greetings from The Netherlands.

TonyD

[DoubleMIDI]

If you don't have any tension measurement information about your strings for any scale length (together with this length), nobody can really help you without cutting a string in pieces and measure its weight (and nobody really wants to do that, I assume).

Since strings are made from different material and often also contains some air between the windings, the effective mass could only be measured by cutting the vibrating part of the string in some useful length (i.e. 1 meter or 10 cm) and and measure its weight. From this you can calculate the effective mass of the string and then use the formula. You cannot weight the whole length of the string because of the different construction and effective mass of the afterlengths.

To get from a known tension of one scale length to the other one, some school maths using two of these equations and setting the known values with some transformation of the equation with the known tension, then replacing the variables in the formula with the unknown tension with the value of the other side of the equation of the transformed known tension formula. (Sorry for not explaining it better, english is not my native language.)

From a practical perspective:
Your scale is just a bit longer than the standard length of about 105 cm. Put your finger 2 cm from the nut on the string and compare it to the open string. The difference to most other masses which the string was made for is the additional tension you need to tune the open string from the normal pitch to this slightly higher pitch. Not much, less than a quarter tone, I guess and therefor not much more tension. With the tuned down solos (by a whole tone) you do much more than compare your longer scale.

I know that this doesn't answer your question, but I hope it will help anyway,

Jörg

[donn]

In case you think it might be worth it, still I wouldn't cut the string up before getting some more confirmation that this will actually lead to a valid tension measurement.

My approach this this problem is, if it's important to know the tension value, then I don't use Pirastro strings.

[TonyD]

Pirastro replies with the following:

'These will be the tensions of Obligato Solo for your double bass:

A1 Solo 29 kp
E2 Solo 30 kp
H3B Solo 31 kp
Fis4 Solo 31 kp'

I think they mean 'kg' instead of 'kp'. But I am tuning the strings down to Orchestra tuning. So that will lower the tension. Is it based on the above figures possible to calculate the exact tension when tuned 1 note down to orchestra?

Thanks,

TonyD

[DoubleMIDI]

They mean kilopond, but on earths surface it is the same tension as putting the same amount of kilogramm at the end of a vertical positioned string. (Other end fixed of course.)

So read kp as kg if you like, even if it is not exactly the same in physics.

[TonyD]

Hi Jörg - yes you are right.

But what is the tension when tuned to orchestra pitch?

Something like 25 kp for the G-string? (just guessing)...

[DoubleMIDI]

Hi TonyD,

not by solving equations but by looking at measurements of other strings I would say about 18 percent less, so 24,1 kp for the G.

Have a look at the following chart and calculate the relation between downtuned Spiro Solo and Spiro Mittel string tensions:

http://baen.tamu.edu/users/rel/perso...ssStrings.html

I know I had some other web source for the formula but cannot remember (it was somewhere on my computer, but it seems it got lost).

You will find more interesting data (and I think also the formula for string tension) by looking into the string sticky "Strings megathreads and important threads" and following the links there.

BTW, thanks for giving us the tension data for Obligato Solo. I never got tension data from Pirastro. Will put it in my personal string database (which is far from ready or complete, I'm still collecting data).

[TonyD]

Hi Jörg,

yes I know this chart, but I did not understand the formula which was reason for me to start this topic.

Anyway, you are right - when I take the following tensions:

spiro solo 3886,1 (tuned down) 25.4 kp
spiro solo 3886,1 (not tuned down) 32.0 kp

then tuning down means a 20 % less tension, at least for the Spiro's. Same would apply to the Obligato I pressume, so:

Obligato solos (not tuned down) 29 kp
Obligato solos (tuned down) 24 kp

roughly. That's quite a nice tension I believe...

Currently I am recovering from an injury (a painfull pinky) and maybe that has to do with the tension. So I am considering Velvet Blue strings, but is my current tension is indeed 24 kp I am quite happy...

Thanks,

TonyD

[DoubleMIDI]

Hi again TonyD,

the Spiro Solos are more equal in tension from G to E as the orchestral, who have less tension on the higher strings and more on the lower. So I took the Mittel D (A) tension and compared it with the Solo D (A).
I think a lot of solo sets are more equal in tension over the four strings than orchestral sets (with the exception of the Velvets which are made for equal tension).
The Velvets would be rather similar in tension to your current set. If you need to bow, the Compas 180 SUIT would be a nice alternative, maybe one kp less tension than your current set.

Jörg

[TonyD]

Hi again Jörg,

according to the Velver site - the Blue Velvet strings have a tension of 25 kg - it would say that is ona bass of 105 mensur. So in my bass - which has a mensur of 107.5 the tension would be a little more than 25 kg. So the Obligato's win I suppose.

I am very much interested in Velvet Compas 180. According to the Velvet website the Compas 180 Suite is also in solo pitch. So that means that the tension of these strings would be 24 kg - 20% = 21 kg.

Is this correct?

And what would be the diffrence between Compas 180 suite SOLO and Compas 180 SOLO light?

compas

Thanks,

TonyD

[DoubleMIDI]

Hi TonyD,

I'm a bit puzzled myself about the different Compas 180 strings. The ones I have seen in (online) shops are the Compas 180 and Compas 180 SUIT. I think these are the two I got high-C strings for testing.
You might want to ask the customer support about the availibility of the different sets at info@velvetstrings.com. Nuno is very helpful.
As I read it on the homepage, I would say the downtuned Solo light has a tension of about 19,8 kg. You might get problems with bowing on D and A with such a low tension and also a volume limit and probably pitch problems depending on volume. I would say it is OK to practise at home during a limited phase of convalescence, but not for playing on stage. You can simulate it by further downtuning your downtuned Obligato Solos by a whole tone to D-G-C-f. Try to play them loud and soft and in higher positions on the middle two strings. If you think thats OK you might want to try the Solo light. I found the compas 180 SUIT tuned to orchestra tuning OK, but thought the regular has a better (jazz pizz) presence and range of dynamics and not too much tension for my left hand because of the higher diameter than steel strings. But I know, this is not your priority, but too less tension will make things problematic.
Perhaps you want to try SuperSensitive Sensicores. The (aluminium wound) high-C I tried had so less tension that I tried to tune it up to get some more resistence. I tuned it up by a fourth and then the string broke. They are cheaper than the Velvets and still what you might want now. The high-C was easy to bow and with a very soft sound (much too soft for my jazz playing). I think the regular set is chromesteel wound, but better check it on their homepage. Slap players use the Sensicore too because of the low tension.

[TonyD]

Hi Jörg,

first of all I would to thank you for your help - you sure do know something about DB strings!

I already, just out of curiosity, downtuned my Obligato Solos a whole tone down. This really has a negatie effect on bowing: less sustain, less volume, less presence. Jazz pizzicato is OK and feels smooth at the fingers. You know what? Pirastro even does not recommend downtuning solos string to orchestra tuning. This is what they say:

'We do not recommend tuning the Solo strings down to orchestra pitch - the string tension will be 18% less. So the tension is very low and you will lose a lot of power. The response will be also more problematical'.

This statement is probably based on a standrad mensur of 105.cm. For my bass (107.5 mensur) downtuning just works fine and results in a tension of 24-25 kp.

I am quite happy now to know that I have this tension. I was afraid my tension was too high. But this is certainly not the case. BTW: I can't imagine somebody playing very relaxed pizzicato an a bass with tension of 32 kp - but - hey - who am I?

I will contact Velvet strings. I already purchased a set of secondhanded Velvet Blue's - but as already stated before I, these strings will have a little but more tension than my current set. Maybe Compas 180 SUIT will be an option one day, will try to find a secondhanded set.

I will check out the SuperSensitive Sensicores - thanks again for the advice!

Herzlichen grüssen,

TonyD

[DoubleMIDI]

Hi TonyD,

I just want to add the following:

My bass has a mensur of 109cm, so a bit longer than yours.

I found out that the Innovation high-C 140B and 140H strings (aluminium wound) that I tested had less tension than the rest of the set. This might be true too for the Sensicore too (I only tested the high-C).

The Innovation 140B is also available as Solo set (140BS).

My personal preference is G and D: Innovation 140B and A and E Spirocore Weich 4/4 (S42W). The spiros have a little bit less tension but ring longer. Bowing is a little bit different, but not much. I can do both Jazz and Classical on this set. Downtuned 140BS Solo strings would loose a bit of dynamic response (this is how I call it, beyond a certain point the string doesn't get much louder).
Personally I dislike solid core synthetic strings (like Obligato) because of the feeling of the left hand. The braided core strings have a much softer feel. But this is just my personal preference.

Maybe Sensicore and downtuned 140BS Solos make too much problems with bowing.

My problem with steel strings was the very small diameter on the high C (less than a mm). Hard to press them down on the fingerboard. So the larger diameter (and soft grip of the left hand) of braided synthetic core strings was enough for me, I really didn't need low tension strings. Just a bit less than Spiro Mittel.

BTW: With 107.5 cm you can even try a bit lower tension 3/4 strings. Even my 109 cm is rather 7/8 than 4/4. I would name anything beyond 110 cm a 4/4.

Good luck with your string testing,

Jörg

[bryanspkr]

Change in tension equals the square of the change in length.
1/2 step is 1.0594. tension change 1.12