Round Wound String Tension - Questions for You Engineers (looking for facts)

[Jim C]

Have searched and have found a lot of contradicting information. This should be a matter of engineering and physics and not a matter of opinion.
Questions regard string tension as in how much pull or stiffness and not the string surface texture.

Here's my questions and assume all things being equal for comparsions in regards to string gauge and alloy types:

1. Does string core have more to do with string tension than than the 3 standard outer wrap materials (pure nickel, stainless steel, and nickel plated stainless)?

2. Assuming the same type of core, is it safe to say that pure nickel wraps have less tension than SS or plated stainless?

3. How much difference in tension (if any) does plating SS wrap with nickel have over unplated SS? I would think that nickel plated SS would have less tension as the base material would be slightly thinner; then again, perhaps the plating process change the characterisitcs of the SS; haven't found any credible sources on this one.

TIA

[knuckle_head]

First; big difference between stiffness and tension. Stiffness is a property of the manufactured string that speaks to how flexible the string itself is, on or off the bass. Tension is the pull on the string itself once it is on the bass and will be the same, given the same mass, whether the string is rigid or flexible.

A rigid string will feel as though it is tighter because it is less inclined to bend under your fingers - but that is a 'feel' thing strictly.

Originally Posted by Jim C

1. Does string core have more to do with string tension than than the 3 standard outer wrap materials (pure nickel, stainless steel, and nickel plated stainless)?

The biggest factor in how stiff/rigid a string is, is how many wraps of wire are on a string; the more wraps there are the stiffer the string will be.

The size and shape of the core will affect how stiff a string is. A round core is measured at its diameter, where a hex core is measured on the flat. Important as there is actually about 10% more material on a hex core wire than there is on a round core wire with the same dimension.

Because of its shape and that there is more material in hex core wire, hex core will be more rigid/stiff and heavier than round core of the same dimension.

After those two factors comes the material properties.

2. Assuming the same type of core, is it safe to say that pure nickel wraps have less tension than SS or plated stainless?

In order, more flexible to less flexible, you have nickel, them plated then straight stainless. Marginal differences here.

By weight/mass, lightest to heaviest, it's nickel, stainless then plated. Nickel and stainless are very very close in weight.

Biggest difference given all of this is that a string of the same diameter is tighter/has more tension if it is made with stainless or nickel than if it were made of nickel plated stainless because plated has more mass.

3. How much difference in tension (if any) does plating SS wrap with nickel have over unplated SS? I would think that nickel plated SS would have less tension as the base material would be slightly thinner; then again, perhaps the plating process change the characterisitcs of the SS; haven't found any credible sources on this one.

TIA

Plated is about 3% heavier than straight stainless. Stainless is .1% heavier than straight nickel.

Again, the heavier the material in the string the looser the string will need to be at pitch, given identical diameters/gauges.

[JTE]

There's another huge factor. Just because two strings are 0.105, that doesn't mean they have the same ratio of wrap wires and core wires. And THAT has a huge impact on the final tension. There's a lot of variables in wound electric bass strings, many of which aren't readily available for measurement outside of the string companies. Not that they're trying to hide anything, but that it'd most likely be appealing to such a small market that they don't waste money on publishing it.

John

[Bassamatic]

It seems that the heavier string must be pulled tighter to get up to pitch, yes? Or am I mis-understanding this -
"Again, the heavier the material in the string the looser the string will need to be at pitch, given identical diameters/gauges."

Also - the wrap material contributes only to the weight, and has little or no tensile strength.

[knuckle_head]

JTE - It is indeed possible by formula to wind two strings that measure .100 and .105, and actually end up with the smaller string having more mass than the larger one. I was surprised by this. It is possible to know this before wire meets machine if one does their due diligence.

Gio S - The heavier a string is the more mass there is. The more mass there is the less tension is required to bring the string to pitch. It's the theory behind upping gauges to increase tension as gauges are the only real stat most string companies make available. D'Addario published their Tension Chart (search for it through Google-it's out there) some years back, and I am publishing one too. My unit weight data has been posted only on my web site to this point.

In general you are correct that a wrapped/coiled wire has no tensile strength. It then becomes a matter of winding technique, and there are tons of ways to skin that cat. As well, if a 4th wrap is applied (and that is the case for nearly all strings .130/.135 or larger - some .125s) a string becomes increasingly rigid. It's why you can hear a difference in tonality from E to B in some sets.

[knuckle_head]

I feel compelled to add that when a wound string is pulled along its length it causes the winds to tighten in toward the center of the string - not unlike the Chinese finger trap toys I played with as a kid. This increases the rigidity of the string somewhat when it is brought up to pitch, and again the more winds there are the more rigid it will become.

[Jim C]

Originally Posted by knuckle_head

First; big difference between stiffness and tension. Stiffness is a property of the manufactured string that speaks to how flexible the string itself is, on or off the bass. Tension is the pull on the string itself once it is on the bass and will be the same, given the same mass, whether the string is rigid or flexible.

A rigid string will feel as though it is tighter because it is less inclined to bend under your fingers - but that is a 'feel' thing strictly.

The biggest factor in how stiff/rigid a string is, is how many wraps of wire are on a string; the more wraps there are the stiffer the string will be.

Thanks Knuckel Head; some of the best info I've read here regarding strings.
Never realized that string tension was not directly related to string stiffness, meaning that I assumed incorrectly that the string that was harder to bend always exerted the most tension on the neck.

Ironically, after I posted last night, I removed the ancient Blues Steels (.105 E) and replaced them with Sunbeams (.100 E).
Truss rod on this bound / blocked Jbass neck was pretty tight and you really couldn't adjust it flat enough without fear or a ski jump. I assumed that the smaller gauge and nickel plating would offer less tension and less rigidity.
The less rigid feel idea came from this quote from DR regarding round core construction:

"Sunbeams feature the easily recognizable feel and flexibility of DR round core construction, with nickel warmth, softness of feel, and increased response to magnetic pickups due to the sensitive magnetic content (compared to stainless steel) of the nickel plated wrap wire"

In reality I found MUCH less string tension (of course smaller gauge was part of this). Neck now has a small and (for me) perfect amount of relief.
Did not feel that much less rigidity though which I thought I would find with newer strings, round core, thinner gauge, etc.

Bottom line is that I miss the whirring growl of the ancient Blue Steels and but really like the fact that the neck is happy.
These DR's don't sound that much different than the Fender 7150's (pure nickel) on another bass.
Is it me, or is there a ton of smoke and mirrors coupled with jive ad copy attached to some of the string industry?