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I've built a skeleton cello (680mm scale length, 79mm fingerboard radius) and due to the high price of cello strings (2-400$ a set?), I found some flatwound bass strings whose string gauges seem to match well (0.100 to 0.045).

Tuning these up to pitch continues to break them. The tension on the strings is immense, more than I feel safe putting on a string (which is why they are breaking, I assume).

Looking at cello strings, they are pretty much the same. A core wound with a (flat) winding. Sure they may be built to produce a better cello tone, but that's not what I'm concerned with right now.

So what's so special about cello strings that allows them to be tuned to pitch without having to be put under so much tension? Is it a thicker/thinner core? All of my physics knowledge points to this making no sense - a string of a given mass must be under a given tension to vibrate at the selected pitch.

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    That's a great question. Cello strings seem to be deeply magical. The most annoying thing is that the expensive sets actually are significantly better than the “cheap” ones. Aug 26, 2021 at 21:42
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    The core is phoenix feathers and unicorn hairs. Aug 26, 2021 at 23:07
  • Because in strings, size DOES matter. A Bass set can run up to $700 Aug 27, 2021 at 13:38
  • Just to check—what are the units of measurement here? Even though I'm a string player, I have no idea what the standard gauge is, and the only sources I can find concern themselves only with gut strings (e.g. gamutmusic.com/cello-equal-tensioned), but those seem to agree on a range of about 1-4 mm. Note that that's not just a general ballpark and you can use anything within that on any of the four strings; the bottom and top strings are almost two octaves apart and need different diameters. From your question, "0.100" makes sense if that's centimeters, but not sure about "0.045" Aug 27, 2021 at 13:52
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    @AndyBonner inches diameter (or thousandths of an inch if you write it as 045 rather than 0.045).
    – hobbs
    Aug 27, 2021 at 14:17

6 Answers 6

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You correctly suggest that "a string of a given mass must be under a given tension to vibrate at the selected pitch". The issue is that you bought flatwound bass strings with the same gauge as some set of cello strings, but that doesn't mean they're the same mass at all. Bass strings are usually made of steel and nickel, which are pretty heavy materials, and flatwounds nearly maximize the amount of material used for a given gauge string.

I found a cello string set with comparable gauges to what you listed- they're made of beef gut! Far less dense than steel. I also found some cello strings which are made of steel, and they're a much smaller gauge, because they'd be too heavy otherwise.

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  • Far less dense and probably a bit stretchier.
    – phoog
    Aug 26, 2021 at 22:02
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    Wait, cello isn't vegan!? Aug 27, 2021 at 8:31
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    @GrimmTheOpiner No more than Jell-O, it sounds like 😑 Aug 27, 2021 at 11:57
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    That's partially incorrect. As other answers point out, the materials used affect the required tension , because the elasticity factor matters a lot. Gut strings are a completely different beast from all metal strings. Don't expect anything like the same sound to be produced. Aug 27, 2021 at 13:42
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    @BrydonGibson Btw, I know of no particular reason why electric cello strings would need to be different than normal ones. Unlike an electric guitar, electric bowed strings don't usually use magnetic pickups but just piezo pickups in the bridge, so the material doesn't matter. Aug 27, 2021 at 14:28
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I'm having a hard time accepting that the bass strings are the same gauge as cello strings. (If so, I've never seen bass strings that small!) Note that the gauge of each string is different (A cello's A is much thinner than its C.) I could maybe accept that the highest bass string (G) might be similar in gauge to a cello C, but I can't imagine how you could get something appropriate for the cello A.

Which would explain a lot—to get a higher pitch from a thicker gauge you have to crank up the tension.

But you can find cheaper cello strings. Look into "steel core" strings, in which the core is simply a few braided steel wires, rather than a synthetic fiber; those seem to be closer to $90 USD.

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A year or so ago I bought a 650mm scale "electric bass" and re-strung it for cello tuning. I ended up using the D string from the bass set (0.067 according to my calipers) as the C string and the three bottom strings from a guitar set (0.046 E, 0.036 A, 0.026 D) as the G, D, and A strings. That worked out pretty well.

Your scale is 30mm longer than mine, so your strings will be a little tighter to achieve the same pitches. You could go a little smaller in diamter, but these diameters should be close.

inch string diameters: [0.026, 0.036, 0.046, 0.067]
  mm string diameters: [0.660, 0.914, 1.168, 1.702]
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First of all, where are you buying strings from? Sure, really good ones will cost that much. But these ones from Gear4Music will only set you back £10. Sure you get what you pay for, but there's definitely an entry-level price available.

More generally though, the string gauge you're quoting is the total diameter of the core plus winding. The core thickness is what dictates how much tension you get on the string, so whether the winding wire is thicker or thinner will have a massive impact. Strings for a bass will almost certainly be constructed with a different core/winding ratio, and the tension on the string will be different to what you want.

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  • Interesting find. Juststrings, stringsbymail, long and mcquade, etc all seem to only have the higher ticket items. Maybe a visit to a local music store is in order, but cello strings are certainly more esoteric than guitar strings Aug 27, 2021 at 12:48
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    The problem is that those really-cheap strings are unsuitable especially for beginners. At least the ones I tried were almost impossible to play – hardly grab the bow hair, and when they do then they rather topple in some weird harmonic rather than a proper note. With careful bow technique it's kind of workable, but a beginner has enough to worry about even with good strings. Aug 27, 2021 at 20:49
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It seems you are ignoring an important parameter: the string gauge is just the diameter and you seem to assume, that equal diameter means equal pitch under equal tension. This is not true, the important part is the oscillating mass which is influenced by the diameter but also - if not more - by the specific weight of the used material (one of the reasons to wind something heavier around the core).

Bass strings are heavier (per length unit), therefore have a lower pitch, which requires more tension to compensate i. e. to reach the higher cello pitches.

Another issue: the cello bow is much lighter and the surface may need reflect this as well.

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  • My mistake seems to stem from accidentally combining multiple sources of data. Cello strings in the 100-45 gauge are perfectly reasonable, and steel core, nickel wound strings are also perfectly reasonable. Combining those two is not reasonable Aug 27, 2021 at 12:49
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There are a few issues to consider. First, is scale length. a full size cello is shorter than a short scale bass by about 2.5 inches but longer than most guitars. That puts them in approximately the same range. This might make you think it could work.

Next is string construction. Electric bass strings are usually made with a solid core and one or more windings. The windings can account for a good part of the string’s thickness. I can’t say for sure but steel cello strings, if they’re like upright bass strings, are probably made from a thick braided core with a relatively thin outer winding, this is very different from a typical electric bass string.

The last and probably most important point is pitch. The bass is tuned E A D G and the cello C G D A. These are the differences in pitch:

Bass E vs cello C: cello is a m6 higher

Bass A vs cello G: cello is a m7 higher

Bass D vs cello D: cello is an 8ve higher

Bass G vs cello A: cello is a M10 higher (!)

THAT is why it won’t work, bass strings aren’t made to be tuned to pitches that high, even with a scale length 2.5 inches shorter. Two of the 4 strings are an octave or more higher! You are trying to tune bass strings way higher than what they were designed for. Cello strings are made to be tuned to those pitches. I believe the materials used and the braided core gives them the strength and flexibility they need to handle that easily,

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  • Scale length- Cello would be more comparable to bass capo 4 than a regular scale bass. You would never tune your bass 2 whole steps too high, but you absolutely could tune bass capo 4 that high... Using short scale as the point of comparison is sorta fudging the numbers. Short scale isn't standard. But never mind. Strings are suitable for a certain tension range, not tuning. And you could buy an ultra-light set of bass strings with a 0.095 low E, and a heavy set of bass strings with a 0.095 low A, and they're actually the same string, just in a different wrapper.
    – Edward
    Aug 28, 2021 at 22:22
  • You can absolutely use bass strings for any tuning and scale length without popping them as long as you just buy the right set of strings.
    – Edward
    Aug 28, 2021 at 22:23
  • @edward following your example of capo 4 the low E would have to be tuned to a G# to give you a cello’s C at the 4th fret, a M3 higher. The A to an Eb, a tritone higher to give you the cello’s G, The D to a Bb, a m6 higher to give a D and the G to an F, a m7, the equivalent to the G strings 10th fret to give you an A at the 4th fret. I certainly wouldn’t attempt tuning even a light .040 G string to an F, almost an octave higher. If you want to try that let me know how it goes. As for buying the right set of strings, the OP was just referring to a standard 4 string set of flat wounds. Aug 29, 2021 at 8:08
  • I don't mean to suggest that OP's set of bass strings will work. But would you tune a 0.030 C bass string to an F (A P4 higher)? This answer might have you believe it's a bad idea, but I would totally try it on a cello, because "being a perfect 4th higher" isn't a concern if the tension is still in a comfortable range. The information in this answer meanders around the "real reason" OP's bass strings don't work, in my opinion.
    – Edward
    Aug 29, 2021 at 16:35
  • @Edward As far as I’m concerned you are going beyond the parameters pf the question by suggesting a .030 C string. I think my answer is reasonable, no other answer explored the disparity in pitch between the two instruments. Aug 29, 2021 at 23:15

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