I don't usually stray over to this side of the sandbox, but I just found out about these strings, and I was very excited, until I found out that the price at Amazon is over $125/set. That's just outrageous for a set of strings that I'm betting are pretty much exactly the same as D'Addario's Chromes guitar strings.
Why do I say that? Because I happen to own a Warwick Custom Shop 30" scale fretless bass guitar that I had them build specifically so that I could tune it in fifths, in cello tuning. After much calculation, I decided to build a set of D'Addario Chromes guitar strings (not bass guitar strings) from singles in .080/.060/.040/.020
The length fit my Warwick fine, but it turned out that the .020, the lightest wound string D'Addario makes in the Chromes line, kept breaking at G3-G#3, and just wouldn't make it up to A3. So, I bit the bullet and bought a set of D'Addario Prelude 4/4 medium tension cello strings, which work great. The silk overlaps the bridge a little bit, but that actually works in my favour, because it slightly dampens the strings for a better sound.
I'm betting you could pick out a custom set of Chromes guitar strings and use them on a cello just fine, since the overall length of the string on a 27.5" scale cello would be about the same as that on my 30" scale bass guitar. According to D'Addario, the Helicore 4ths tuning strings are "stranded steel core/stainless wrap", where the Chromes are made with D'Addario's standard hex core and a stainless wrap.
The .080 is the heaviest Chromes guitar string, so if you started there and worked your way up, balancing the tension for fourths tuning, you'd probably have a nice set. But here's the question no one seems to be answering: Is the lowest string in the Helicore 4ths tuning set meant to be tuned to E1, or E2? I ask, because the early jazz greats who experimented with cello, like Oscar Pettiford, apparently tuned their cellos an octave higher than a bass, or E2. I'm not saying the .080 wouldn't work at E1, but I wouldn't expect it to sound great, considering the standard gauge for a 34" scale bass guitar at E1 is generally .105
In any case, here's a video I just made of my Warwick. It's only 0:10 long, but you can hear the tuning. I hope you found my comments interesting.
http://youtu.be/W7MgTQBRU8Y
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