Hello all For a while now I've been researching and testing out various strings and scale lengths / tunings for an extended range nylon string guitar. I thought I would share this information here in the rare event that it would be useful or interesting to somebody Hopefully it will be a useful resource for anyone considering tuning up nylon strings, experimenting with scale lengths, or purchasing existing ERCs at various lengths from companies like Bartolex. There are existing guitarists tuning to A4 on classical guitars but they are using brighter sounding strong materials like carbon (commonly a Japanese fishing line brand, in fact). Nylon strings are a huge amount weaker (although far more elastic) than steel strings, so tuning above E4 is even more of a problem than it is on electric guitar. I wanted to keep things easy and use the readily available clear rectified nylon strings from D'addario, paired with their silverwound basses (possibly extended by the thicker silver wounds that LaBella offer). This string combination is wonderful in tone and is the basis of the D'addario 'Classics' series. Typically, the high E on a 25" scale with nylons would be in the realms of 024 and 027 nylon strings, ranging between 11 and 15lbs of tension. If you are not familiar with classical guitar and that gauge sounds huge to you, it's simply because the strings are far lighter in weight than steel, thus need to be bigger to create good tension. I am testing 018, 019, 020, 021, and 022 strings to find the tension they are comfortable at. For now I am going to break just two of each string.* They are being tested on 24.75" length and I will write the tension as such. I will consider a string completely safe to play at a full step short of its breaking point. Due to what I have read from guitarists using the carbon strings, and breaking some of these thinner strings in the past, I am expecting to not be able to tune up past G with normal strings. But I want my numbers, so here goes! D'addario NYL018 - unit weight .00000916 E4, 6.3lbs, seems to be the minimum tension I can enjoy on classical guitar. Sounds quite good and would suit low tension players. I presume this is the tuning for which this string is designed and can hold with zero issues. F4, 7.1lbs - great F4#, 8lbs - I am impressed. Strong tone, great tension. I wasn't expecting to make it this far as one string I tried in the past broke shortly after E!* G4, 8.9lbs - What is this black magic? G4#, 10lbs - I know nylon strings stretch forever and take a long time to tune I'm but I'm very surprised to have made it this far. I'm sure it's not very durable but stretching to G4# without breaking certainly shows little issue in playing a semitone or too lower. A4, 11.2lbs - Incredible result. Of course it feels incredibly brittle and stretched. I am guessing this is near breaking point as it's not detuning a huge amount as nylon strings usually do for a few days as they stretch. It held for 1 hour before I decided... A4#, 12.6lbs - Not even kidding - I'm mindblown at this point. B4, 14.2lbs - It stopped 10 cents short and took 5 winds of the tuner to continue. It actually reached B, before breaking The second string performed pretty much the same but broke at A#. D'addario NYL019 - unit weight .00001020 E4, 7lbs - Really nice sounding low tension string. The slightly bigger gauge is certainly an improvement in feel and tone. F4, 7.9lbs - Great F4#, 8.9lbs - Perfect tension for this string G4, 9.9lbs - Fine G4#, 11.2lbs - Projects very well, these are far better results than I was hoping for based on my brief experience tuning up in the past! A4, 12.5lbs - Well it made it, the tension and tone is good but I'm quite sure it wouldn't last very long, it's not holding tuning fantastically. A4#, 14.1lbs - It made it to A# and wouldn't go higher no matter how much I stretched it. Fell back to A very easily, and broke upon reaching A# again. The second string I tested was again much the same - broke just before A#. I let it stretch out in G# for quite a while and it seems it would be a solid option for that at this scale length, if a bit brittle still. D'addario NYL020 - Unit weight .00001130 E4 - 7.8lbs - Fine F4 - 8.7lbs - Very nice tone - seeing such low tensions and being used to electric it's hard to believe these strings feel tight enough! F4# - 9.8lbs - Great, probably the perfect F# string at this length. G4 - 11lbs - Very nice and thick enough to be loud G4# - 12.4lbs - Quite alright. Snapped not far above G#. Second string snapped at G# D'addario NYL021 - Unit weight .00001246 E4 - 8.6lbs - Fine F4 - 9.6lbs - Great string for F tuning F4# - 10.8lbs - Nice G4 - 12.1lbs - Projects very well G4# - 13.6lbs - It made it, on and off between retuning, but broke. The second string broke just short of G#. D'addario NYL022 - Unit weight .00001368 E4 - 9.4lbs - Fine. I guess we are into ordinary string territory now and can't expect too much range. F4 - 10.6lbs - Wonderful, strong tone and volume - probably the best string for this tuning given the strings generally used for E. F4# - 11.9lbs - Sounds a little brittle G4 - 13.3lbs - Holding up quite well after lots of stretching, should be close to breaking tension I expect G4# -15lbs = Just made it and broke The second string behaved just the same. ----------------------- You can see from these results the gradual increase in strength across the gauges (though the thinnest reached higher tensions slightly, which is somewhat inconsistant), as well as the increased tension required to reach notes and how they relate. Hopefully this information is helpful to anyone in deciding what they can tune to on their guitar, or what kind of lengths to use on a custom design without relying on carbon strings. I am very happy with these results, I was not expecting to make it above F# or G reliably. I will be able to tune my upcoming custom to G, G#, or A, without going quite as short as I thought I may have to! Happy stretching! *Of course, testing just two strings isn't the most reliable experiment so there certainly needs to be some leeway and I wouldn't play strings too close to the breaking tensions I have found here. Like I said, at least a semitone lower, preferably closer to two. The fact that one of the 018s broke at E for me in the past is a clear indicator that there will be variable results. But it's certainly possible to achieve great higher pitches with these strings and it must be what they were designed for given the very low tension at E!