string tension

[ggunn]

i don't not believe it's just about the mass.

take a string's wrap (say an .010") without a core on it and pull on it. it will just uncoil with practically no resistance. now take a straight wire the same gauge as the wrap and pull on it. it will have quite a bit of tension.

IME, small cored heavy strings can flop around due to their mass/weight, but heavy cored thinly wrapped strings are very stiff.

Stiffness and tension are not the same thing. In your example it's stiffness (resistance to bending) you are talking about, not tension. Tension acts in the direction of the length of the string, stiffness acts perpendicular to the length of the string. High tension strings feel stiff, but stiff strings are not necessarily high tension.

 

[7flat5]

Stiffness and tension are not the same thing. In your example it's stiffness (resistance to bending) you are talking about, not tension. Tension acts in the direction of the length of the string, stiffness acts perpendicular to the length of the string. High tension strings feel stiff, but stiff strings are not necessarily high tension.

Absolutely right. There's a third parameter that some people refer to as "tension" and that is elasticity. Actual tension in pounds is only proportional to mass (given pitch and length remain constant, which they usually do). There is also resistance to bending, and resistance to stretching. Elasticity and flexibility are mostly about the core of the string, but tension is only about mass/unit length. Elasticity has a lot more affect on feel than flexibility, I think. It determines how hard it is to displace the string down to the fingerboard.

 

[knuckle_head]

Elasticity and flexibility are mostly about the core of the string, but tension is only about mass/unit length. Elasticity has a lot more affect on feel than flexibility, I think.

Manufacturing has as much to do with stiffness and elasticity as core choice. The more tension on individual wraps in the manufacturing process the more stiff and less elastic a string will be.

Additionally, if you play a string at a lower tension than it was made with you will get the same affect.

Most strings are made with 25 to 30 pounds of tension in their making - some are made right up to the elastic limit of the wire. This is closely held information generally speaking. But I can with reasonable certainty recommend playing with tensions in excess of 30 pounds - regardless of gauge (review data on B strings ladies and gentlemen) to get the best voice out of your string choice. Between 35 and 40 pounds is ideal.

 

[7flat5]

Manufacturing has as much to do with stiffness and elasticity as core choice. The more tension on individual wraps in the manufacturing process the more stiff and less elastic a string will be.

That's actually very interesting. I guess I was thinking that, since wrap tension varies, but does not vary that much, the core properties would tend to be more determinant of elasticity than wrap, generally. I can, though, certainly understand how wrap variables could have a huge effect on flexibility.

I'm interested in your point that it also has "as much" of an effect on elasticity of the finished string, though. How does that happen? Compressed wrappings tend to preserve a certain tension on the core wire, even when not strung up under tension on the instrument. Would that tend to make the string more elastic, i.e. easier to stretch up to a certain point (the tension under which it was wrapped)?

 

[knuckle_head]

If excessive tension is used in the string's winding process any or all wraps can be applied in a manner that each wire is near, reached or exceeded its elastic capacity. The core suffers undo stress if this is the case. You need stretch left in a string or it is dead out of the envelope.

Ideally strings are manufactured well under their intended pitch tension - which by default is well under elasticity limits. This results in a longer lasting string.

 

[Munjibunga]

There was a tip in Gary Willis' 101 bass tips book that said to use a PC board spacers to increase tension on the lower strings. They are 1/4 inch spacers you put the string through first, then feed the string through the bridge. Seems like a pretty cool idea, but I havent tried it yet.

It's a silly idea, and it doesn't change the tension in the string at all. I can't believe someone of Willis's calibre would ascribe to crap like that.

 

[FunkMetalBass]

Hmm ... it seems obvious to me that the larger core string will have more mass and more tension. EDIT: AH! of course, the hex core itself has gaps in it's structure!

Yes, it's true. Examining a core and single torus wrap down the length of the string, a larger core clearly creates more space between the wrap and the core.

However, the potential issue came in regarding the space between the wraps themselves. The larger the wrap, the larger the gap.

The math shows that the volume of space between core and wrap is ultimately larger than between wraps, so, at least with regards to hex core (which make up at least half the strings in today's market).

I know, I'm late getting back to this.

 

[FunkMetalBass]

Part of the reason a hex core has more mass by measure than round core is that hex core is measured on the flat surface of the hexagon - there is 18% more mass in an identically gauge hex core than round core.

FWIW there is a way to wind a .100 to have more mass than a .105 so formula is not moot.

A stiff string may not be in your interest - it arrests harmonics, and a thick core will do the same thing.

That's interesting. I was under the impression that the round core would circumscribe a hex core, but now you're telling me that it's actually inscribed?

Well, my math still holds in the case of hex-core comparison.

The more wraps you have the more latitude you've got, and in general no manufacturer wants to use a wrap finer than .006 because it takes too much machine time and material, but if you consider the gaps - yes, mind the gaps - the finer the wire used the more solid it is as a layer.

There are things you cannot force a wound string to be by formula as you end up with warbles that make a string look ugly - though they will function just fine.

Too much more and each of you will be my competition . . .

I'd like a .085, 6-wrap E-string please.

For physics' sake, I've looked everywhere and can't find any information on the string-making supplies. No worry about competition here either.

...not enough explosions for my liking in your field!

When you're done with your baking soda/vinegar volcanoes, come step into the vast, explosive world of nuclear physics.

 

[dj150888]

Funkmetalbass, I ran over your figures when I had a chance this morning, it all looks fine to me. I would've presented it as a general formula myself because thats just how I'm used to working, but the specific example works and generalises to a formula just fine.

And nuclear physics? No thanks, nowadays its all focussed on making things safer and more efficient, I'll keep my volcanoes!

 

[FunkMetalBass]

Funkmetalbass, I ran over your figures when I had a chance this morning, it all looks fine to me. I would've presented it as a general formula myself because that's just how I'm used to working, but the specific example works and generalizes to a formula just fine.

And nuclear physics? No thanks, nowadays its all focussed on making things safer and more efficient, I'll keep my volcanoes!

I wanted to post the general formula (I'm a math major), but I had to hurriedly crunch numbers before a dinner engagement and just didn't have time to write up anything elegant.

I guess I could do it now...but meh.

 

[ixlramp]

Yes, it's true. Examining a core and single torus wrap down the length of the string, a larger core clearly creates more space between the wrap and the core.

However, the potential issue came in regarding the space between the wraps themselves. The larger the wrap, the larger the gap.

The math shows that the volume of space between core and wrap is ultimately larger than between wraps, so, at least with regards to hex core (which make up at least half the strings in today's market).

Oh cool, I didn't know how to calculate the volume of a wrap wire ... So essentially, assuming all materials are the same density. If you have 2 strings of the same gauge but different hex core size, the one with a a larger hex core will have slightly less mass, and therefore slightly less tension?

 

[cnltb]

Does anyone know which brands have higher tension?

Pyramid seemed quite high tension when I used them.
I found them to be great sounding strings!

 

[ixlramp]

but if you consider the gaps - yes, mind the gaps - the finer the wire used the more solid it is as a layer.

... 'more solid' as in denser? or stiffer?

I imagine it's best to minimise the number of wraps for more flexibility, hence the Circle K 2 wrap E strings.

 

[FunkMetalBass]

Oh cool, I didn't know how to calculate the volume of a wrap wire ... So essentially, assuming all materials are the same density. If you have 2 strings of the same gauge but different hex core size, the one with a a larger hex core will have slightly less mass, and therefore slightly less tension?

Theoretically speaking, yes. Uniform density implies that more volume = more mass (since density = mass/volume by definition). Because there is no way to know for sure what the exact angle of wrap is, we can make an assumption that the wrap is just a bunch of tiny tori. So the volume of the torus + the volume of a hexagonal prism, all multiplied by the density is the mass of the string.

However, this is only the case for single-wrap strings.

In multi-wrap strings, clearly the larger has a larger gap in it, potentially equating to less string volume and ergo, lower mass. I haven't done the math (and frankly, don't really care to right now), but I suspect that, in multi-wrap hex-core strings, the string with a smaller wrap wire actually has more mass.

 

[knuckle_head]

. . . . I suspect that, in multi-wrap hex-core strings, the string with a smaller wrap wire actually has more mass.

This, basically.

 

[TheSuzie]

Okay, so now let's analyze rope core strings

 

[knuckle_head]

Okay, so now let's analyze rope core strings

Infinitely flexible - as strings should be

 

[TheSuzie]

Infinitely flexible - as strings should be

So, if I understand this correctly, you are saying that the perceived stiffness of a rope core string is much more directly related to the tension than with a simple solid core string. Is the reason we don't see this construction in bass guitar strings mostly due to cost? It is pretty common construction in double bass strings but those are much more costly.

S

 

[FunkMetalBass]

Rope-core? I'm unfamiliar with these. Are they made of typical rope (with fibers of hemp, etc)? Or does "rope-core" simply denote the design of the core as looking something like galvanized steel rope?

 

[TheSuzie]

Usually steel though other metals are used. Yes, the core wires are twisted like a rope.